MT48LC16M16A2TG-75L:D - Micron Technology

SDR SDRAM

MT48LC64M4A2 – 16 Meg x 4 x 4 banks

MT48LC32M8A2 – 8 Meg x 8 x 4 banks

MT48LC16M16A2 – 4 Meg x 16 x 4 banks

Features

•PC100- and PC133-compliant

•Fully synchronous; all signals registered on positive

edge of system clock

•Internal, pipelined operation; column address can

be changed every clock cycle

•Internal banks for hiding row access/precharge

•Programmable burst lengths: 1, 2, 4, 8, or full page

•Auto precharge, includes concurrent auto pre-

charge and auto refresh modes

•Self refresh mode (not available on AT devices)

•Auto refresh

–64ms, 8192-cycle (commercial and industrial)

–16ms, 8192-cycle (automotive)

•LVTTL-compatible inputs and outputs

•Single +3.3V ±0.3V power supply

Table 1: Address Table

Parameter 64 Meg x 4 32 Meg x 8

16 Meg

x 16

Configuration 16 Meg x 4

x 4 banks

8 Meg x 8 x

4 banks

4 Meg x 16

x 4 banks

Refresh count 8K 8K 8K

Row addressing 8K A[12:0] 8K A[12:0] 8K A[12:0]

Bank addressing 4 BA[1:0] 4 BA[1:0] 4 BA[1:0]

Column

addressing

2K A[9:0],

A11

1K A[9:0] 512 A[8:0]

Table 2: Key Timing Parameters

CL = CAS (READ) latency

Speed

Grade

Clock

Frequency

Access Time Setup

Time

Hold

TimeCL = 2 CL = 3

-6A 167 MHz –5.4ns 1.5ns 0.8ns

-7E 143 MHz –5.4ns 1.5ns 0.8ns

-75 133 MHz –5.4ns 1.5ns 0.8ns

-7E 133 MHz 5.4ns –1.5ns 0.8ns

-75 100 MHz 6ns –1.5ns 0.8ns

Options Marking

•Configurations

–64 Meg x 4 (16 Meg x 4 x 4 banks) 64M4

–32 Meg x 8 (8 Meg x 8 x 4 banks) 32M8

–16 Meg x 16 (4 Meg x 16 x 4 banks) 16M16

•Write recovery (tWR)

–tWR = 2 CLK1A2

•Plastic package – OCPL2

–54-pin TSOP II OCPL2 (400 mil)

(standard)

–54-pin TSOP II OCPL2 (400 mil)

Pb-free

–60-ball FBGA (x4, x8) (8mm x 16mm) FB

–60-ball FBGA (x4, x8) (8mm x 16mm)

Pb-free

–54-ball VFBGA (x16) (8mm x 14 mm) FG

–54-ball VFBGA (x16) (8mm x 14 mm)

Pb-free

•Timing – cycle time

–6ns @ CL = 3 (x8, x16 only) -6A

–7.5ns @ CL = 3 (PC133) -75

–7.5ns @ CL = 2 (PC133) -7E

•Self refresh

–Standard None

–Low power L3

•Operating temperature range

–Commercial (0˚C to +70˚C) None

–Industrial (–40˚C to +85˚C) IT

–Automotive (–40˚C to +105˚C) AT3

•Revision :D

Notes: 1. See Micron technical note TN-48-05 on

Micron's Web site.

2. Off-center parting line.

3. Contact Micron for availability.

256Mb: x4, x8, x16 SDRAM

Features

PDF: 09005aef8091e6d1

256Mb_sdr.pdf - Rev. N 1/10 EN 1Micron Technology, Inc. reserves the right to change products or specifications without notice.

Products and specifications discussed herein are subject to change by Micron without notice.

Table 3: 256Mb SDR Part Numbering

Part Numbers Architecture Package

MT48LC64M4A2TG 64 Meg x 4 54-pin TSOP II

MT48LC64M4A2P 64 Meg x 4 54-pin TSOP II

MT48LC64M4A2FB164 Meg x 4 60-ball FBGA

MT48LC64M4A2BB164 Meg x 4 60-ball FBGA

MT48LC32M8A2TG 32 Meg x 8 54-pin TSOP II

MT48LC32M8A2P 32 Meg x 8 54-pin TSOP II

MT48LC32M8A2FB132 Meg x 8 60-ball FBGA

MT48LC32M8A2BB132 Meg x 8 60-ball FBGA

MT48LC16M16A2TG 16 Meg x 16 54-pin TSOP II

MT48LC16M16A2P 16 Meg x 16 54-pin TSOP II

MT48LC16M16A2FG 16 Meg x 16 54-ball FBGA

MT48LC16M16A2BG 16 Meg x 16 54-ball FBGA

Note: 1. Actual FBGA part marking is shown in Package Dimensions (page 16).

FBGA Part Marking Decoder

Due to space limitations, FBGA-packaged components have an abbreviated part marking that is different from the

part number. Micron’s FBGA part marking decoder is available at www.micron.com/decoder.

256Mb: x4, x8, x16 SDRAM

Features

PDF: 09005aef8091e6d1

256Mb_sdr.pdf - Rev. N 1/10 EN 2Micron Technology, Inc. reserves the right to change products or specifications without notice.

Contents

General Description ......................................................................................................................................... 8

Automotive Temperature ............................................................................................................................. 8

Functional Block Diagrams ............................................................................................................................... 9

Pin and Ball Assignments and Descriptions ..................................................................................................... 12

Package Dimensions ...................................................................................................................................... 16

Temperature and Thermal Impedance ............................................................................................................ 19

Electrical Specifications .................................................................................................................................. 22

Electrical Specifications – IDD Parameters ........................................................................................................ 24

Electrical Specifications – AC Operating Conditions ......................................................................................... 26

Functional Description ................................................................................................................................... 31

Commands .................................................................................................................................................... 32

COMMAND INHIBIT .................................................................................................................................. 32

NO OPERATION (NOP) .............................................................................................................................. 33

LOAD MODE REGISTER (LMR) ................................................................................................................... 33

ACTIVE ...................................................................................................................................................... 33

READ ......................................................................................................................................................... 34

WRITE ....................................................................................................................................................... 35

PRECHARGE .............................................................................................................................................. 36

BURST TERMINATE ................................................................................................................................... 36

AUTO REFRESH ......................................................................................................................................... 37

SELF REFRESH ........................................................................................................................................... 37

Truth Tables ................................................................................................................................................... 38

Initialization .................................................................................................................................................. 43

Mode Register ................................................................................................................................................ 46

Burst Length .............................................................................................................................................. 48

Burst Type ................................................................................................................................................. 48

CAS Latency ............................................................................................................................................... 50

Operating Mode ......................................................................................................................................... 50

Write Burst Mode ....................................................................................................................................... 50

Bank/Row Activation ...................................................................................................................................... 51

READ Operation ............................................................................................................................................. 52

WRITE Operation ........................................................................................................................................... 61

Burst Read/Single Write .............................................................................................................................. 68

PRECHARGE Operation .................................................................................................................................. 69

Auto Precharge ........................................................................................................................................... 69

AUTO REFRESH Operation ............................................................................................................................. 81

SELF REFRESH Operation .............................................................................................................................. 83

Power-Down .................................................................................................................................................. 85

Clock Suspend ............................................................................................................................................... 86

Revision History ............................................................................................................................................. 89

Rev. N – 1/10 .............................................................................................................................................. 89

Rev. M – 11/08 ............................................................................................................................................ 89

Rev. L – 8/07 ............................................................................................................................................... 89

Rev. K – 2/07 .............................................................................................................................................. 90

Rev. K – 6/06 .............................................................................................................................................. 90

Rev. J – 3/05 ............................................................................................................................................... 90

Rev. H – 2/05 .............................................................................................................................................. 90

Rev. H – 10/04 ............................................................................................................................................ 90

Rev. G – 8/03 .............................................................................................................................................. 90

Rev. F – 1/03 ............................................................................................................................................... 90

256Mb: x4, x8, x16 SDRAM

PDF: 09005aef8091e6d1

256Mb_sdr.pdf - Rev. N 1/10 EN 3Micron Technology, Inc. reserves the right to change products or specifications without notice.

Rev. E – 3/02 ............................................................................................................................................... 91

Rev. D – 7/01 .............................................................................................................................................. 91

Rev. C – 3/01 .............................................................................................................................................. 91

Rev. B – 10/00 ............................................................................................................................................. 92

Rev. A – 11/99 ............................................................................................................................................. 92

256Mb: x4, x8, x16 SDRAM

PDF: 09005aef8091e6d1

256Mb_sdr.pdf - Rev. N 1/10 EN 4Micron Technology, Inc. reserves the right to change products or specifications without notice.

List of Tables

Table 1: Address Table .................................................................................................................................... 1

Table 2: Key Timing Parameters ...................................................................................................................... 1

Table 3: 256Mb SDR Part Numbering ............................................................................................................... 2

Table 4: Pin and Ball Descriptions .................................................................................................................. 15

Table 5: Temperature Limits .......................................................................................................................... 19

Table 6: Thermal Impedance Simulated Values .............................................................................................. 20

Table 7: Absolute Maximum Ratings .............................................................................................................. 22

Table 8: DC Electrical Characteristics and Operating Conditions ..................................................................... 22

Table 9: Capacitance ..................................................................................................................................... 23

Table 10: IDD Specifications and Conditions (-6A) ........................................................................................... 24

Table 11: IDD Specifications and Conditions (-7E, -75) .................................................................................... 24

Table 12: Electrical Characteristics and Recommended AC Operating Conditions (-6A) ................................... 26

Table 13: Electrical Characteristics and Recommended AC Operating Conditions (-7E, -75) ............................. 27

Table 14: AC Functional Characteristics (-6A) ................................................................................................. 28

Table 15: AC Functional Characteristics (-7E, -75) .......................................................................................... 29

Table 16: Truth Table – Commands and DQM Operation ................................................................................ 32

Table 17: Truth Table – Current State Bank n, Command to Bank n ................................................................. 38

Table 18: Truth Table – Current State Bank n, Command to Bank m ................................................................ 40

Table 19: Truth Table – CKE .......................................................................................................................... 42

Table 20: Burst Definition Table .................................................................................................................... 49

256Mb: x4, x8, x16 SDRAM

PDF: 09005aef8091e6d1

256Mb_sdr.pdf - Rev. N 1/10 EN 5Micron Technology, Inc. reserves the right to change products or specifications without notice.

List of Figures

Figure 1: 64 Meg x 4 Functional Block Diagram ................................................................................................ 9

Figure 2: 32 Meg x 8 Functional Block Diagram .............................................................................................. 10

Figure 3: 16 Meg x 16 Functional Block Diagram ............................................................................................. 11

Figure 4: 54-Pin TSOP (Top View) .................................................................................................................. 12

Figure 5: 60-Ball FBGA (Top View) ................................................................................................................. 13

Figure 6: 54-Ball VFBGA (Top View) ............................................................................................................... 14

Figure 7: 54-Pin Plastic TSOP (400 mil) ........................................................................................................... 16

Figure 8: 60-Ball FBGA "FB" (8mm x 16mm) (x4, x8) ....................................................................................... 17

Figure 9: 54-Ball VFBGA "FG" (8mm x 14mm) (x16) ........................................................................................ 18

Figure 10: Example: Temperature Test Point Location, 54-Pin TSOP (Top View) .............................................. 20

Figure 11: Example: Temperature Test Point Location, 54-Ball VFBGA (Top View) ........................................... 21

Figure 12: Example: Temperature Test Point Location, 60-Ball FBGA (Top View) ............................................. 21

Figure 13: ACTIVE Command ........................................................................................................................ 33

Figure 14: READ Command ........................................................................................................................... 34

Figure 15: WRITE Command ......................................................................................................................... 35

Figure 16: PRECHARGE Command ................................................................................................................ 36

Figure 17: Initialize and Load Mode Register .................................................................................................. 45

Figure 18: Mode Register Definition ............................................................................................................... 47

Figure 19: CAS Latency .................................................................................................................................. 50

Figure 20: Example: Meeting tRCD (MIN) When 2 < tRCD (MIN)/tCK < 3 ......................................................... 51

Figure 21: Consecutive READ Bursts .............................................................................................................. 53

Figure 22: Random READ Accesses ................................................................................................................ 54

Figure 23: READ-to-WRITE ............................................................................................................................ 55

Figure 24: READ-to-WRITE With Extra Clock Cycle ......................................................................................... 56

Figure 25: READ-to-PRECHARGE .................................................................................................................. 56

Figure 26: Terminating a READ Burst ............................................................................................................. 57

Figure 27: Alternating Bank Read Accesses ..................................................................................................... 58

Figure 28: READ Continuous Page Burst ........................................................................................................ 59

Figure 29: READ – DQM Operation ................................................................................................................ 60

Figure 30: WRITE Burst ................................................................................................................................. 61

Figure 31: WRITE-to-WRITE .......................................................................................................................... 62

Figure 32: Random WRITE Cycles .................................................................................................................. 63

Figure 33: WRITE-to-READ ............................................................................................................................ 63

Figure 34: WRITE-to-PRECHARGE ................................................................................................................. 64

Figure 35: Terminating a WRITE Burst ........................................................................................................... 65

Figure 36: Alternating Bank Write Accesses .................................................................................................... 66

Figure 37: WRITE – Continuous Page Burst .................................................................................................... 67

Figure 38: WRITE – DQM Operation ............................................................................................................... 68

Figure 39: READ With Auto Precharge Interrupted by a READ ......................................................................... 70

Figure 40: READ With Auto Precharge Interrupted by a WRITE ....................................................................... 71

Figure 41: READ With Auto Precharge ............................................................................................................ 72

Figure 42: READ Without Auto Precharge ....................................................................................................... 73

Figure 43: Single READ With Auto Precharge .................................................................................................. 74

Figure 44: Single READ Without Auto Precharge ............................................................................................. 75

Figure 45: WRITE With Auto Precharge Interrupted by a READ ....................................................................... 76

Figure 46: WRITE With Auto Precharge Interrupted by a WRITE ...................................................................... 76

Figure 47: WRITE With Auto Precharge .......................................................................................................... 77

Figure 48: WRITE Without Auto Precharge ..................................................................................................... 78

Figure 49: Single WRITE With Auto Precharge ................................................................................................ 79

Figure 50: Single WRITE Without Auto Precharge ........................................................................................... 80

256Mb: x4, x8, x16 SDRAM

PDF: 09005aef8091e6d1

256Mb_sdr.pdf - Rev. N 1/10 EN 6Micron Technology, Inc. reserves the right to change products or specifications without notice.

Figure 51: Auto Refresh Mode ........................................................................................................................ 82

Figure 52: Self Refresh Mode ......................................................................................................................... 84

Figure 53: Power-Down Mode ....................................................................................................................... 85

Figure 54: Clock Suspend During WRITE Burst ............................................................................................... 86

Figure 55: Clock Suspend During READ Burst ................................................................................................ 87

Figure 56: Clock Suspend Mode ..................................................................................................................... 88

256Mb: x4, x8, x16 SDRAM

PDF: 09005aef8091e6d1

256Mb_sdr.pdf - Rev. N 1/10 EN 7Micron Technology, Inc. reserves the right to change products or specifications without notice.

General Description

The 256Mb SDRAM is a high-speed CMOS, dynamic random-access memory contain-

ing 268,435,456 bits. It is internally configured as a quad-bank DRAM with a synchro-

nous interface (all signals are registered on the positive edge of the clock signal, CLK).

Each of the x4’s 67,108,864-bit banks is organized as 8192 rows by 2048 columns by 4

bits. Each of the x8’s 67,108,864-bit banks is organized as 8192 rows by 1024 columns by

8 bits. Each of the x16’s 67,108,864-bit banks is organized as 8192 rows by 512 columns

by 16 bits.

Read and write accesses to the SDRAM are burst-oriented; accesses start at a selected

location and continue for a programmed number of locations in a programmed se-

quence. Accesses begin with the registration of an ACTIVE command, which is then

followed by a READ or WRITE command. The address bits registered coincident with

the ACTIVE command are used to select the bank and row to be accessed (BA[1:0] select

the bank; A[12:0] select the row). The address bits registered coincident with the READ

or WRITE command are used to select the starting column location for the burst access.

The SDRAM provides for programmable read or write burst lengths (BL) of 1, 2, 4, or 8

locations, or the full page, with a burst terminate option. An auto precharge function

may be enabled to provide a self-timed row precharge that is initiated at the end of the

burst sequence.

The 256Mb SDRAM uses an internal pipelined architecture to achieve high-speed oper-

ation. This architecture is compatible with the 2n rule of prefetch architectures, but it

also allows the column address to be changed on every clock cycle to achieve a high-

speed, fully random access. Precharging one bank while accessing one of the other

three banks will hide the PRECHARGE cycles and provide seamless, high-speed, random-

access operation.

The 256Mb SDRAM is designed to operate in 3.3V memory systems. An auto refresh

mode is provided, along with a power-saving, power-down mode. All inputs and out-

puts are LVTTL-compatible.

SDRAMs offer substantial advances in DRAM operating performance, including the abil-

ity to synchronously burst data at a high data rate with automatic column-address

generation, the ability to interleave between internal banks to hide precharge time, and

the capability to randomly change column addresses on each clock cycle during a burst

access.

Automotive Temperature

The automotive temperature (AT) option adheres to the following specifications:

•16ms refresh rate

•Self refresh not supported

•Ambient and case temperature cannot be less than –40°C or greater than +105°C

256Mb: x4, x8, x16 SDRAM

General Description

PDF: 09005aef8091e6d1

256Mb_sdr.pdf - Rev. N 1/10 EN 8Micron Technology, Inc. reserves the right to change products or specifications without notice.

Functional Block Diagrams

Figure 1: 64 Meg x 4 Functional Block Diagram

RAS#

CAS#

ROW-

ADDRESS

MUX

CLK

CS#

WE#

CKE

CONTROL

LOGIC

COLUMN-

ADDRESS

COUNTER/

LATCH

MODE REGISTER

COMMAND

DECODE

A[12:0]

BA[1:0]

DQM

ADDRESS

2048

(x4)

8192

I/O GATING

DQM MASK LOGIC

READ DATA LATCH

WRITE DRIVERS

COLUMN

DECODER

BANK0

MEMORY

ARRAY

(8192 x 2048 x 4)

BANK0

ROW-

ADDRESS

LATCH

DECODER

8192

SENSE AMPLIFIERS

BANK

CONTROL

LOGIC

DQ[3:0]

DATA

INPUT

DATA

OUTPUT

BANK1

BANK2

BANK3

1 1

REFRESH

COUNTER

256Mb: x4, x8, x16 SDRAM

Functional Block Diagrams

PDF: 09005aef8091e6d1

256Mb_sdr.pdf - Rev. N 1/10 EN 9Micron Technology, Inc. reserves the right to change products or specifications without notice.

Figure 2: 32 Meg x 8 Functional Block Diagram

RAS#

CAS#

ROW-

ADDRESS

MUX

CLK

CS#

WE#

CKE

CONTROL

LOGIC

COLUMN-

ADDRESS

COUNTER/

LATCH

MODE REGISTER

COMMAND

DECODE

A[12:0]

BA[1:0]

DQM

ADDRESS

1024

(x8)

8192

I/O GATING

DQM MASK LOGIC

READ DATA LATCH

WRITE DRIVERS

COLUMN

DECODER

BANK0

MEMORY

ARRAY

(8192 x 1024 x 8)

BANK0

ROW-

ADDRESS

LATCH

DECODER

8192

SENSE AMPLIFIERS

BANK

CONTROL

LOGIC

DQ[7:0]

DATA

INPUT

DATA

OUTPUT

BANK1

BANK2

BANK3

1 1

REFRESH

COUNTER

256Mb: x4, x8, x16 SDRAM

Functional Block Diagrams

PDF: 09005aef8091e6d1

256Mb_sdr.pdf - Rev. N 1/10 EN 10 Micron Technology, Inc. reserves the right to change products or specifications without notice.

Figure 3: 16 Meg x 16 Functional Block Diagram

RAS#

CAS#

ROW-

ADDRESS

MUX

CLK

CS#

WE#

CKE

CONTROL

LOGIC

COLUMN-

ADDRESS

COUNTER/

LATCH

MODE REGISTER

COMMAND

DECODE

A[12:0]

BA[1:0]

DQML,

DQMH

ADDRESS

512

(x16)

8192

I/O GATING

DQM MASK LOGIC

READ DATA LATCH

WRITE DRIVERS

COLUMN

DECODER

BANK0

MEMORY

ARRAY

(8192 x 512 x 16)

BANK0

ROW-

ADDRESS

LATCH

DECODER

8192

SENSE AMPLIFIERS

BANK

CONTROL

LOGIC

DQ[15:0]

DATA

INPUT

DATA

OUTPUT

BANK1

BANK2

BANK3

2 2

REFRESH

COUNTER

256Mb: x4, x8, x16 SDRAM

Functional Block Diagrams

PDF: 09005aef8091e6d1

256Mb_sdr.pdf - Rev. N 1/10 EN 11 Micron Technology, Inc. reserves the right to change products or specifications without notice.

Pin and Ball Assignments and Descriptions

Figure 4: 54-Pin TSOP (Top View)

VDD

DQ0

VDDQ

DQ1

DQ2

VSSQ

DQ3

DQ4

VDDQ

DQ5

DQ6

VSSQ

DQ7

VDD

DQML

WE#

CAS#

RAS#

CS#

BA0

BA1

A10

VDD

VSS

DQ15

VSSQ

DQ14

DQ13

VDDQ

DQ12

DQ11

VSSQ

DQ10

DQ9

VDDQ

DQ8

VSS

DQMH

CLK

CKE

A12

A11

VSS

x8x16 x16x8 x4x4

DQ0

DQ1

DQ2

DQ3

DQ0

DQ1

DQ7

DQ6

DQ5

DQ4

DQM

DQ3

DQ2

DQM

Note: 1. The # symbol indicates that the signal is active LOW. A dash (-) indicates that the x8 and

x4 pin function is the same as the x16 pin function.

256Mb: x4, x8, x16 SDRAM

Pin and Ball Assignments and Descriptions

PDF: 09005aef8091e6d1

256Mb_sdr.pdf - Rev. N 1/10 EN 12 Micron Technology, Inc. reserves the right to change products or specifications without notice.

Figure 5: 60-Ball FBGA (Top View)

12 3 45678

Depopulated Balls

NC VSS

NC VSSQ

VDDQ DQ3

NC NC

NC VSSQ

VDDQ DQ2

NC NC

NC VSS

NC DQM

NC CK

A12 CKE

A11 A9

A8 A7

A6 A5

A4 VSS

VDD NC

VDDQ NC

DQ0 VSSQ

NC NC

VDDQ NC

DQ1 VSSQ

NC NC

VDD NC

WE# CAS#

RAS# NC

NC CS#

BA1 BA0

A0 A10

A2 A1

VDD A3

12 3 45678

Depopulated Balls

DQ7 VSS

NC VSSQ

VDDQ DQ6

DQ5 NC

NC VSSQ

VDDQ DQ4

NC NC

NC VSS

NC DQM

NC CK

A12 CKE

A11 A9

A8 A7

A6 A5

A4 VSS

VDD DQ0

VDDQ NC

DQ1 VSSQ

NC DQ2

VDDQ NC

DQ3 VSSQ

NC NC

VDD NC

WE# CAS#

RAS# NC

NC CS#

BA1 BA0

A0 A10

A2 A1

VDD A3

64 Meg x 4 SDRAM

8mm x 16mm FB

32 Meg x 8 SDRAM

8mm x 16mm FB

256Mb: x4, x8, x16 SDRAM

Pin and Ball Assignments and Descriptions

PDF: 09005aef8091e6d1

256Mb_sdr.pdf - Rev. N 1/10 EN 13 Micron Technology, Inc. reserves the right to change products or specifications without notice.

Figure 6: 54-Ball VFBGA (Top View)

12345678 9

Depopulated Balls

VSS DQ15

DQ14 DQ13

DQ12 DQ11

DQ10 DQ9

DQ8 NC

UDQM CLK

A12 A11

A8 A7

VSS A5

VSSQ

VDDQ

VSSQ

VDDQ

VSS

CKE

VDDQ

VSSQ

VDDQ

VSSQ

VDD

CAS#

BA0

DQ0 VDD

DQ2 DQ1

DQ4 DQ3

DQ6 DQ5

LDQM DQ7

RAS# WE#

BA1 CS#

A1 A10

A2 VDD

Note: 1. The balls at A4, A5, and A6 are absent from the physical package. They are included to

illustrate that rows 4, 5, and 6 exist, but contain no solder balls.

256Mb: x4, x8, x16 SDRAM

Pin and Ball Assignments and Descriptions

PDF: 09005aef8091e6d1

256Mb_sdr.pdf - Rev. N 1/10 EN 14 Micron Technology, Inc. reserves the right to change products or specifications without notice.

Table 4: Pin and Ball Descriptions

Symbol Type Description

CLK Input Clock: CLK is driven by the system clock. All SDRAM input signals are sampled on the positive

edge of CLK. CLK also increments the internal burst counter and controls the output registers.

CKE Input Clock enable: CKE activates (HIGH) and deactivates (LOW) the CLK signal. Deactivating the

clock provides precharge power-down and SELF REFRESH operation (all banks idle), active pow-

er-down (row active in any bank), or CLOCK SUSPEND operation (burst/access in progress).

CKE is synchronous except after the device enters power-down and self refresh modes, where

CKE becomes asynchronous until after exiting the same mode. The input buffers, including

CLK, are disabled during power-down and self refresh modes, providing low standby power.

CKE may be tied HIGH.

CS# Input Chip select: CS# enables (registered LOW) and disables (registered HIGH) the command decod-

er. All commands are masked when CS# is registered HIGH, but READ/WRITE bursts already in

progress will continue, and DQM operation will retain its DQ mask capability while CS# is

HIGH. CS# provides for external bank selection on systems with multiple banks. CS# is consid-

ered part of the command code.

CAS#, RAS#, WE# Input Command inputs: RAS#, CAS#, and WE# (along with CS#) define the command being entered.

x4, x8:

DQM

x16:

DQML, DQMH

LDQM, UDQM

(54-ball)

Input Input/output mask: DQM is sampled HIGH and is an input mask signal for write accesses and

an output enable signal for read accesses. Input data is masked during a WRITE cycle. The

output buffers are High-Z (two-clock latency) during a READ cycle. LDQM corresponds to

DQ[7:0], and UDQM corresponds to DQ[15:8]. LDQM and UDQM are considered same-state

when referenced as DQM.

BA[1:0] Input Bank address input(s): BA[1:0] define to which bank the ACTIVE, READ, WRITE, or PRECHARGE

command is being applied.

A[12:0] Input Address inputs: A[12:0] are sampled during the ACTIVE command (row address A[12:0]) and

READ or WRITE command (column address A[9:0] and A11 for x4; A[9:0] for x8; A[8:0] for x16;

with A10 defining auto precharge) to select one location out of the memory array in the re-

spective bank. A10 is sampled during a PRECHARGE command to determine if all banks are to

be precharged (A10 HIGH) or bank selected by BA[1:0] (LOW). The address inputs also provide

the op-code during a LOAD MODE REGISTER command.

x16:

DQ[15:0]

I/O Data input/output: Data bus for x16 (pins 4, 7, 10, 13, 42, 45, 48, and 51 are NC for x8; and

pins 2, 4, 7, 8, 10, 13, 42, 45, 47, 48, 51, and 53 are NC for x4).

x8:

DQ[7:0]

I/O Data input/output: Data bus for x8 (pins 2, 8, 47, 53 are NC for x4).

x4:

DQ[3:0]

I/O Data input/output: Data bus for x4.

VDDQ Supply DQ power: DQ power to the die for improved noise immunity.

VSSQ Supply DQ ground: DQ power to the die for improved noise immunity.

VDD Supply Power supply: +3.3V ±0.3V.

VSS Supply Ground.

NC –These should be left unconnected. For x4 and x8 parts, G1 is a no connect, but may be used as

A12 in future designs.

256Mb: x4, x8, x16 SDRAM

Pin and Ball Assignments and Descriptions

PDF: 09005aef8091e6d1

256Mb_sdr.pdf - Rev. N 1/10 EN 15 Micron Technology, Inc. reserves the right to change products or specifications without notice.

Package Dimensions

Figure 7: 54-Pin Plastic TSOP (400 mil)

SEE DETAIL A

0.10 +0.10

-0.05

0.15 +0.03

-0.02

2X R 1.00

2X R 0.75

0.80 TYP

(FOR REFERENCE

ONLY)

2X 0.71

0.50 ±0.10

PIN #1 ID

DETAIL A

22.22 ±.08

10.16 ±0.08

11.76 ±0.20

0.375 ±0.075 TYP

1.2 MAX

0.25

0.80

2X 0.10

2.80 GAGE PLANE

PLATED LEAD FINISH: 90% Sn, 10% Pb OR 100%Sn

PLASTIC PACKAGE MATERIAL: EPOXY NOVOLAC

PACKAGE WIDTH AND LENGTH DO NOT

INCLUDE MOLD PROTRUSION. ALLOWABLE

PROTRUSION IS 0.25 PER SIDE.

0.10

Notes: 1. All dimensions are in millimeters.

2. Package width and length do not include mold protrusion; allowable mold protrusion is

0.25mm per side.

3. 2X means the notch is present in two locations (both ends of the device).

256Mb: x4, x8, x16 SDRAM

Package Dimensions

PDF: 09005aef8091e6d1

256Mb_sdr.pdf - Rev. N 1/10 EN 16 Micron Technology, Inc. reserves the right to change products or specifications without notice.

Figure 8: 60-Ball FBGA "FB" (8mm x 16mm) (x4, x8)

BALL #1 ID

SUBSTRATE:

PLASTIC LAMINATE

ENCAPSULATION MATERIAL:

EPOXY NOVOLAC

SOLDER BALL MATERIAL:

62% Sn, 36% Pb, 2% Ag OR

96.5% Sn. 3% Ag, 0.5% Cu

SEATING PLANE

0.850 ±0.05

0.155 ±0.013

0.10 A

0.80

TYP

16.00 ±0.10

11.20

1.20 MAX

5.60

8.00 ±0.05

BALL #1 ID

BALL A1

BALL

0.80

TYP

4.00 ±0.05

2.80

2.40 ±0.05

CTR

8.00 ±0.10

5.60

60X Ø 0.45

DIMENSIONS APPLY

TO SOLDER BALLS

POST REFLOW. PRE-

REFLOW DIAMETER

IS 0.42 ON A 0.33 NSMD

BALL PAD.

Notes: 1. All dimensions are in millimeters.

2. Recommended pad size for PCB is 0.33mm ±0.025mm.

3. Topside part-marking decoder is available at www.micron.com/decoder.

256Mb: x4, x8, x16 SDRAM

Package Dimensions

PDF: 09005aef8091e6d1

256Mb_sdr.pdf - Rev. N 1/10 EN 17 Micron Technology, Inc. reserves the right to change products or specifications without notice.

Figure 9: 54-Ball VFBGA "FG" (8mm x 14mm) (x16)

BALL A1 ID

1.00 MAX

MOLD COMPOUND: EPOXY NOVOLAC

SUBSTRATE MATERIAL: PLASTIC LAMINATE

SOLDER BALL MATERIAL: 62% Sn, 36% Pb, 2% Ag OR

96.5% Sn, 3%Ag, 0.5% Cu

SOLDER MASK DEFINED BALL PADS: Ø 0.40

14.00 ±0.10

BALL A1

BALL A9

BALL A1 ID

0.80 TYP

7.00 ±0.05

8.00 ±0.10

4.00 ±0.05

3.20 ±0.05

0.65 ±0.05

SEATING PLANE

6.40

0.10 C

54X Ø0.45

SOLDER BALL DIAMETER

REFERS TO POST REFLOW

CONDITION. THE PRE-

REFLOW DIAMETER IS Ø0.42

Notes: 1. All dimensions are in millimeters.

2. Recommended pad size for PCB is 0.4mm ±0.065mm.

3. Topside part-marking decoder is available at www.micron.com/decoder.

256Mb: x4, x8, x16 SDRAM

Package Dimensions

PDF: 09005aef8091e6d1

256Mb_sdr.pdf - Rev. N 1/10 EN 18 Micron Technology, Inc. reserves the right to change products or specifications without notice.

Temperature and Thermal Impedance

It is imperative that the SDRAM device’s temperature specifications, shown in Table 5

(page 19), be maintained to ensure the junction temperature is in the proper operat-

ing range to meet data sheet specifications. An important step in maintaining the

proper junction temperature is using the device’s thermal impedances correctly. The

thermal impedances are listed in Table 6 (page 20) for the applicable die revision and

packages being made available. These thermal impedance values vary according to the

density, package, and particular design used for each device.

Incorrectly using thermal impedances can produce significant errors. Read Micron tech-

nical note TN-00-08, “Thermal Applications” prior to using the thermal impedances

listed in Table 6 (page 20). To ensure the compatibility of current and future designs,

contact Micron Applications Engineering to confirm thermal impedance values.

The SDRAM device’s safe junction temperature range can be maintained when the TC

specification is not exceeded. In applications where the device’s ambient temperature

is too high, use of forced air and/or heat sinks may be required to satisfy the case tem-

perature specifications.

Table 5: Temperature Limits

Parameter Symbol Min Max Unit Notes

Operating case temperature Commercial TC0 80 °C 1, 2, 3, 4

Industrial –40 90

Automotive –40 105

Junction temperature Commercial TJ0 85 °C 3

Industrial –40 95

Automotive –40 110

Ambient temperature Commercial TA0 70 °C 3, 5

Industrial –40 85

Automotive –40 105

Peak reflow temperature TPEAK –260 °C

Notes: 1. MAX operating case temperature, TC, is measured in the center of the package on the

top side of the device, as shown in Figure 10 (page 20), Figure 11 (page 21), and Fig-

ure 12 (page 21).

2. Device functionality is not guaranteed if the device exceeds maximum TC during operation.

3. All temperature specifications must be satisfied.

4. The case temperature should be measured by gluing a thermocouple to the top-center

of the component. This should be done with a 1mm bead of conductive epoxy, as de-

fined by the JEDEC EIA/JESD51 standards. Take care to ensure that the thermocouple

bead is touching the case.

5. Operating ambient temperature surrounding the package.

256Mb: x4, x8, x16 SDRAM

Temperature and Thermal Impedance

PDF: 09005aef8091e6d1

256Mb_sdr.pdf - Rev. N 1/10 EN 19 Micron Technology, Inc. reserves the right to change products or specifications without notice.

Table 6: Thermal Impedance Simulated Values

Die

Revision Package Substrate

Θ JA (°C/W)

Airflow =

0m/s

Θ JA (°C/W)

Airflow =

1m/s

Θ JA (°C/W)

Airflow =

2m/s Θ JB (°C/W) Θ JC (°C/W)

D 54-pin TSOP 2-layer 81 63.8 57.6 45.3 10.3

4-layer 44 47.3 44.5 39.1

54-ball VFBGA 2-layer 64.9 50.8 44.8 31.4 3.2

4-layer 51.5 41.6 38.1 31.4

60-ball FBGA 2-layer 67 51.2 47.8 19.7 6.7

4-layer 40.9 35.1 32.2 18.6

Notes: 1. For designs expected to last beyond the die revision listed, contact Micron Applications

Engineering to confirm thermal impedance values.

2. Thermal resistance data is sampled from multiple lots, and the values should be viewed

as typical.

3. These are estimates; actual results may vary.

Figure 10: Example: Temperature Test Point Location, 54-Pin TSOP (Top View)

22.22mm

11.11mm

Test point

10.16mm

5.08mm

256Mb: x4, x8, x16 SDRAM

Temperature and Thermal Impedance

PDF: 09005aef8091e6d1

256Mb_sdr.pdf - Rev. N 1/10 EN 20 Micron Technology, Inc. reserves the right to change products or specifications without notice.

Figure 11: Example: Temperature Test Point Location, 54-Ball VFBGA (Top View)

8.00mm

4.00mm

Test point

14.00mm

7.00mm

Figure 12: Example: Temperature Test Point Location, 60-Ball FBGA (Top View)

8.00mm

4.00mm

Test point

8.00mm

16.00mm

256Mb: x4, x8, x16 SDRAM

Temperature and Thermal Impedance

PDF: 09005aef8091e6d1

256Mb_sdr.pdf - Rev. N 1/10 EN 21 Micron Technology, Inc. reserves the right to change products or specifications without notice.

Electrical Specifications

Stresses greater than those listed may cause permanent damage to the device. This is a

stress rating only, and functional operation of the device at these or any other condi-

tions above those indicated in the operational sections of this specification is not

implied. Exposure to absolute maximum rating conditions for extended periods may

affect reliability.

Table 7: Absolute Maximum Ratings

Voltage/Temperature Symbol Min Max Unit Notes

Voltage on VDD/VDDQ supply relative to VSS VDD/VDDQ –1 +4.6 V 1

Voltage on inputs, NC, or I/O balls relative to VSS VIN –1 +4.6

Storage temperature (plastic) TSTG –55 +150 °C

Power dissipation – – 1 W

Note: 1. VDD and VDDQ must be within 300mV of each other at all times. VDDQ must not exceed

VDD.

Table 8: DC Electrical Characteristics and Operating Conditions

Notes 1–3 apply to all parameters and conditions; VDD/VDDQ = +3.3V ±0.3V

Parameter/Condition Symbol Min Max Unit Notes

Supply voltage VDD, VDDQ 3 3.6 V

Input high voltage: Logic 1; All inputs VIH 2 VDD + 0.3 V 4

Input low voltage: Logic 0; All inputs VIL –0.3 +0.8 V 4

Output high voltage: IOUT = –4mA VOH 2.4 –V

Output low voltage: IOUT = 4mA VOL –0.4 V

Input leakage current:

Any input 0V ≤ VIN ≤ VDD (All other balls not under test = 0V)

IL–5 5 μA

Output leakage current: DQ are disabled; 0V ≤ VOUT ≤ VDDQ IOZ –5 –5 μA

Operating temperature: Commercial TA0 +70 ˚C

Industrial TA–40 +85 ˚C

Automotive TA–40 +105 ˚C

Notes: 1. All voltages referenced to VSS.

2. The minimum specifications are used only to indicate cycle time at which proper opera-

tion over the full temperature range is ensured; (0°C ≤ TA ≤ +70°C (commercial), –40°C ≤

TA ≤ +85°C (industrial), and –40°C ≤ TA ≤ +105°C (automotive)).

3. An initial pause of 100μs is required after power-up, followed by two AUTO REFRESH

commands, before proper device operation is ensured. (VDD and VDDQ must be powered

up simultaneously. VSS and VSSQ must be at same potential.) The two AUTO REFRESH com-

mand wake-ups should be repeated any time the tREF refresh requirement is exceeded.

4. VIH overshoot: VIH,max = VDDQ + 2V for a pulse width ≤ 3ns, and the pulse width cannot

be greater than one-third of the cycle rate. VIL undershoot: VIL,min = –2V for a pulse

width ≤3ns.

256Mb: x4, x8, x16 SDRAM

Electrical Specifications

PDF: 09005aef8091e6d1

256Mb_sdr.pdf - Rev. N 1/10 EN 22 Micron Technology, Inc. reserves the right to change products or specifications without notice.

Table 9: Capacitance

Note 1 applies to all parameters and conditions

Package Parameter Symbol Min Max Unit Notes

TSOP "TG" package Input capacitance: CLK CL1 2.5 3.5 pF 2

Input capacitance: All other input-only

balls

CL2 2.5 3.8 pF 3

Input/output capacitance: DQ CL0 4 6 pF 4

FBGA "FB" and "FG" packages Input capacitance: CLK CL1 1.5 3.5 pF 5

Input capacitance: All other input-only

balls

CL2 1.5 3.8 pF 6

Input/output capacitance: DQ CL0 3 6 pF 7

Notes: 1. This parameter is sampled. VDD, VDDQ = +3.3V; f = 1 MHz, TA = 25°C; pin under test

biased at 1.4V.

2. PC100 specifies a maximum of 4pF.

3. PC100 specifies a maximum of 5pF.

4. PC100 specifies a maximum of 6.5pF.

5. PC133 specifies a minimum of 2.5pF.

6. PC133 specifies a minimum of 2.5pF.

7. PC133 specifies a minimum of 3.0pF.

256Mb: x4, x8, x16 SDRAM

Electrical Specifications

PDF: 09005aef8091e6d1

256Mb_sdr.pdf - Rev. N 1/10 EN 23 Micron Technology, Inc. reserves the right to change products or specifications without notice.

Electrical Specifications – IDD Parameters

Table 10: IDD Specifications and Conditions (-6A)

Notes 1–5 apply to all parameters and conditions; VDD/VDDQ = +3.3V ±0.3V

Parameter/Condition Symbol -6A Unit Notes

Operating current: Active mode; Burst = 2; READ or WRITE; tRC = tRC (MIN) IDD1 135 mA 6, 9, 10,

Standby current: Power-down mode; All banks idle; CKE = LOW IDD2 2μA12

Standby current: Active mode; CKE = HIGH; CS# = HIGH; All banks active af-

ter tRCD met; No accesses in progress

IDD3 40 mA 6, 8, 10,

Operating current: Burst mode; Continuous burst; READ or WRITE; All banks

active

IDD4 135 mA 6, 9, 10,

Auto refresh current: CKE = HIGH; CS# = HIGH tRFC = tRFC (MIN) IDD5 285 mA 6, 8, 9,

10, 11, 12

tRFC = 7.813μsIDD6 3.5 mA

tRFC = 1.953μs (AT) IDD6 8 mA

Self refresh current: CKE ≤ 0.2V IDD7 2.5 mA 7

Table 11: IDD Specifications and Conditions (-7E, -75)

Notes 1–5 apply to all parameters and conditions; VDD/VDDQ = +3.3V ±0.3V

Parameter/Condition Symbol

Max

Unit Notes-7E -75

Operating current: Active mode; Burst = 2; READ or WRITE; tRC = tRC

(MIN)

IDD1 135 125 mA 6, 9, 10,

Standby current: Power-down mode; All banks idle; CKE = LOW IDD2 2 2 mA 13

Standby current: Active mode; CKE = HIGH; CS# = HIGH; All banks ac-

tive after tRCD met; No accesses in progress

IDD3 40 40 mA 6, 8, 10,

Operating current: Burst mode; Page burst; READ or WRITE; All banks

active

IDD4 135 135 mA 6, 9, 10,

Auto refresh current: CKE = HIGH; CS# = HIGH tRFC = tRFC (MIN) IDD5 285 270 mA 6, 8, 9,

10, 13,

tRFC = 7.813μsIDD6 3.5 3.5 mA

tRFC = 1.953μs (AT) IDD6 8 8 mA

Self refresh current: CKE ≤ 0.2V Standard IDD7 2.5 2.5 mA

Low power (L) IDD7 1.5 1.5 mA 7

Notes: 1. All voltages referenced to VSS.

2. The minimum specifications are used only to indicate cycle time at which proper opera-

tion over the full temperature range is ensured; (0°C ≤ TA ≤ +70°C (commercial), –40°C ≤

TA ≤ +85°C (industrial), and –40°C ≤ TA ≤ +105°C (automotive)).

3. An initial pause of 100μs is required after power-up, followed by two AUTO REFRESH

commands, before proper device operation is ensured. (VDD and VDDQ must be powered

up simultaneously. VSS and VSSQ must be at same potential.) The two AUTO REFRESH com-

mand wake-ups should be repeated any time the tREF refresh requirement is exceeded.

4. AC operating and IDD test conditions have VIL = 0V and VIH = 3.0V using a measurement

reference level of 1.5V. If the input transition time is longer than 1ns, then the timing is

256Mb: x4, x8, x16 SDRAM

Electrical Specifications – IDD Parameters

PDF: 09005aef8091e6d1

256Mb_sdr.pdf - Rev. N 1/10 EN 24 Micron Technology, Inc. reserves the right to change products or specifications without notice.

measured from VIL, max and VIH,min and no longer from the 1.5V midpoint. CLK should

always be 1.5V referenced to crossover. Refer to Micron technical note TN-48-09.

5. IDD specifications are tested after the device is properly initialized.

6. IDD is dependent on output loading and cycle rates. Specified values are obtained with

minimum cycle time and the outputs open.

7. Enables on-chip refresh and address counters.

8. Other input signals are allowed to transition no more than once every two clocks and

are otherwise at valid VIH or VIL levels.

9. The IDD current will increase or decrease proportionally according to the amount of fre-

quency alteration for the test condition.

10. Address transitions average one transition every two clocks.

11. PC100 specifies a maximum of 4pF.

12. PC100 specifies a maximum of 5pF.

13. For -75, CL = 3 and tCK = 7.5ns; for -7E, CL = 2 and tCK = 7.5ns.

14. CKE is HIGH during REFRESH command period tRFC (MIN) else CKE is LOW. The IDD6 limit

is actually a nominal value and does not result in a fail value.

256Mb: x4, x8, x16 SDRAM

Electrical Specifications – IDD Parameters

PDF: 09005aef8091e6d1

256Mb_sdr.pdf - Rev. N 1/10 EN 25 Micron Technology, Inc. reserves the right to change products or specifications without notice.

Electrical Specifications – AC Operating Conditions

Table 12: Electrical Characteristics and Recommended AC Operating Conditions (-6A)

Notes 1, 2, 4, 5, 7, and 20 apply to all parameters and conditions

Parameter Symbol

-6A

Unit NotesMin Max

Access time from CLK (positive edge) CL = 3 tAC(3) –5.4 ns 18

Address hold time tAH 0.8 –ns

Address setup time tAS 1.5 –ns

CLK high-level width tCH 2.5 –ns

CLK low-level width tCL 2.5 –ns

Clock cycle time CL = 3 tCK(3) 6 –ns 14

CKE hold time tCKH 0.8 –ns

CKE setup time tCKS 1.5 –ns

CS#, RAS#, CAS#, WE#, DQM hold time tCMH 0.8 –ns

CS#, RAS#, CAS#, WE#, DQM setup time tCMS 1.5 1.5 ns

Data-in hold time tDH 0.8 –ns

Data-in setup time tDS 1.5 –ns

Data-out High-Z time CL = 3 tHZ –5.4 ns 6

Data-out Low-Z time tLZ 1 –ns

Data-out hold time (load) tOH 3 –ns

Data-out hold time (no load) tOHn1.8 –ns 19

ACTIVE-to-PRECHARGE command tRAS 42 120,000 ns

ACTIVE-to-ACTIVE command period tRC 60 –ns

ACTIVE-to-READ or WRITE delay tRCD 18 –ns

Refresh period (8192 rows) tREF –64 ms

Refresh period – automotive (8192 rows) tREFAT –16

AUTO REFRESH period tRFC 60 –ns

PRECHARGE command period tRP 18 –ns

ACTIVE bank a to ACTIVE bank b command tRRD 12 –ns 3

Transition time tT 0.3 1.2 ns

WRITE recovery time tWR 1 CLK +

6ns

–ns

12 –ns 16

Exit SELF REFRESH-to-ACTIVE command tXSR 67 –ns 12

256Mb: x4, x8, x16 SDRAM

Electrical Specifications – AC Operating Conditions

PDF: 09005aef8091e6d1

256Mb_sdr.pdf - Rev. N 1/10 EN 26 Micron Technology, Inc. reserves the right to change products or specifications without notice.

Table 13: Electrical Characteristics and Recommended AC Operating Conditions (-7E, -75)

Notes 1, 2, 4, 5, 7, and 20 apply to all parameters and conditions

Parameter Symbol

-7E -75

Unit NotesMin Max Min Max

Access time from CLK (positive edge) CL = 3 tAC(3) –5.4 –5.4 ns 18

CL = 2 tAC(2) –5.4 –6

Address hold time tAH 0.8 –0.8 –ns

Address setup time tAS 1.5 –1.5 –ns

CLK high-level width tCH 2.5 –2.5 –ns

CLK low-level width tCL 2.5 –2.5 –ns

Clock cycle time CL = 3 tCK(3) 7 –7.5 –ns 14

CL = 2 tCK(2) 7.5 –10 –

CKE hold time tCKH 0.8 –0.8 –ns

CKE setup time tCKS 1.5 –1.5 –ns 21

CS#, RAS#, CAS#, WE#, DQM hold time tCMH 0.8 –0.8 –ns

CS#, RAS#, CAS#, WE#, DQM setup time tCMS 1.5 –1.5 –ns

Data-in hold time tDH 0.8 –0.8 –ns

Data-in setup time tDS 1.5 –1.5 –ns

Data-out High-Z time CL = 3 tHZ(3) –5.4 –5.4 ns 6

CL = 2 tHZ(2) –5.4 –6 ns

Data-out Low-Z time tLZ 1 –1–ns

Data-out hold time (load) tOH 3 –3–ns

Data-out hold time (no load) tOHn1.8 –1.8 –ns 19

ACTIVE-to-PRECHARGE command tRAS 37 120,0

44 120,0

ACTIVE-to-ACTIVE command period tRC 60 –66 –ns

ACTIVE-to-READ or WRITE delay tRCD 15 –20 –ns

Refresh period (8192 rows) tREF –64 –64 ms

Refresh period – automotive (8192 rows) tREFAT –16 –16 ms

AUTO REFRESH period tRFC 66 –66 –ns

PRECHARGE command period tRP 15 –20 –ns

ACTIVE bank a to ACTIVE bank b command tRRD 14 –15 –tCK

Transition time tT 0.3 1.2 0.3 1.2 ns 3

WRITE recovery time tWR 1 CLK

+ 7ns

–1 CLK

7.5ns

–ns 15

14 –15 –16

Exit SELF REFRESH-to-ACTIVE command tXSR 67 –75 –ns 12

256Mb: x4, x8, x16 SDRAM

Electrical Specifications – AC Operating Conditions

PDF: 09005aef8091e6d1

256Mb_sdr.pdf - Rev. N 1/10 EN 27 Micron Technology, Inc. reserves the right to change products or specifications without notice.

Table 14: AC Functional Characteristics (-6A)

Notes 1–5 and note 7 apply to all parameters and conditions

Parameter Symbol -6 Unit Notes

Last data-in to burst STOP command tBDL 1 tCK 11

READ/WRITE command to READ/WRITE command tCCD 1 tCK 11

Last data-in to new READ/WRITE command tCDL 1 tCK 11

CKE to clock disable or power-down entry mode tCKED 1 tCK 8

Data-in to ACTIVE command tDAL 4 tCK 9, 13

Data-in to PRECHARGE command tDPL 2 tCK 10, 13

DQM to input data delay tDQD 0 tCK 11

DQM to data mask during WRITEs tDQM 0 tCK 11

DQM to data High-Z during READs tDQZ 2 tCK 11

WRITE command to input data delay tDWD 0 tCK 11

LOAD MODE REGISTER command to ACTIVE or REFRESH command tMRD 2 tCK 17

CKE to clock enable or power-down exit setup mode tPED 1 tCK 8

Last data-in to PRECHARGE command tRDL 2 tCK 10, 13

Data-out High-Z from PRECHARGE command CL = 3tROH(3) 3 tCK 11

256Mb: x4, x8, x16 SDRAM

Electrical Specifications – AC Operating Conditions

PDF: 09005aef8091e6d1

256Mb_sdr.pdf - Rev. N 1/10 EN 28 Micron Technology, Inc. reserves the right to change products or specifications without notice.

Table 15: AC Functional Characteristics (-7E, -75)

Notes 1–5 and note 7 apply to all parameters and conditions

Parameter Symbol -7E -75 Unit Notes

Last data-in to burst STOP command tBDL 1 1 tCK 11

READ/WRITE command to READ/WRITE command tCCD 1 1 tCK 11

Last data-in to new READ/WRITE command tCDL 1 1 tCK 11

CKE to clock disable or power-down entry mode tCKED 1 1 tCK 8

Data-in to ACTIVE command tDAL 4 5 tCK 9, 13

Data-in to PRECHARGE command tDPL 2 2 tCK 10, 13

DQM to input data delay tDQD 0 0 tCK 11

DQM to data mask during WRITEs tDQM 0 0 tCK 11

DQM to data High-Z during READs tDQZ 2 2 tCK 11

WRITE command to input data delay tDWD 0 0 tCK 11

LOAD MODE REGISTER command to ACTIVE or REFRESH command tMRD 2 2 tCK 17

CKE to clock enable or power-down exit setup mode tPED 1 1 tCK 8

Last data-in to PRECHARGE command tRDL 2 2 tCK 10, 13

Data-out High-Z from PRECHARGE command CL = 3 tROH(3) 3 3 tCK 11

CL = 2 tROH(2) 2 2 tCK 11

Notes: 1. The minimum specifications are used only to indicate cycle time at which proper opera-

tion over the full temperature range (0˚C ≤ TA ≤ +70˚C commercial temperature, -40˚C ≤

TA ≤ +85˚C industrial temperature, and -40˚C ≤ TA ≤ +105˚C automotive temperature) is

ensured.

2. An initial pause of 100μs is required after power-up, followed by two AUTO REFRESH

commands, before proper device operation is ensured. (VDD and VDDQ must be powered

up simultaneously. VSS and VSSQ must be at same potential.) The two AUTO REFRESH

command wake-ups should be repeated any time the tREF refresh requirement is excee-

ded.

3. AC characteristics assume tT = 1ns.

4. In addition to meeting the transition rate specification, the clock and CKE must transit

between VIH and VIL (or between VIL and VIH) in a monotonic manner.

5. Outputs measured at 1.5V with equivalent load:

50pF

6. tHZ defines the time at which the output achieves the open circuit condition; it is not a

reference to VOH or VOL. The last valid data element will meet tOH before going High-Z.

7. AC operating and IDD test conditions have VIL = 0V and VIH = 3.0V using a measurement

reference level of 1.5V. If the input transition time is longer than 1ns, then the timing is

measured from VIL,max and VIH,min and no longer from the 1.5V midpoint. CLK should

always be 1.5V referenced to crossover. Refer to Micron technical note TN-48-09.

8. Timing is specified by tCKS. Clock(s) specified as a reference only at minimum cycle rate.

9. Timing is specified by tWR plus tRP. Clock(s) specified as a reference only at minimum

cycle rate.

10. Timing is specified by tWR.

256Mb: x4, x8, x16 SDRAM

Electrical Specifications – AC Operating Conditions

PDF: 09005aef8091e6d1

256Mb_sdr.pdf - Rev. N 1/10 EN 29 Micron Technology, Inc. reserves the right to change products or specifications without notice.

11. Required clocks are specified by JEDEC functionality and are not dependent on any tim-

ing parameter.

12. CLK must be toggled a minimum of two times during this period.

13. Based on tCK = 7.5ns for -75 and -7E, 6ns for -6A.

14. The clock frequency must remain constant (stable clock is defined as a signal cycling with-

in timing constraints specified for the clock pin) during access or precharge states

(READ, WRITE, including tWR, and PRECHARGE commands). CKE may be used to reduce

the data rate.

15. Auto precharge mode only. The precharge timing budget (tRP) begins at 7ns for -7E and

7.5ns for -75 after the first clock delay and after the last WRITE is executed.

16. Precharge mode only.

17. JEDEC and PC100 specify three clocks.

18. tAC for -75/-7E at CL = 3 with no load is 4.6ns and is guaranteed by design.

19. Parameter guaranteed by design.

20. PC100 specifies a maximum of 6.5pF.

21. For operating frequencies ≤ 45 MHz, tCKS = 3.0ns.

22. Auto precharge mode only. The precharge timing budget (tRP) begins 6ns for -6A after

the first clock delay, after the last WRITE is executed. May not exceed limit set for pre-

charge mode.

256Mb: x4, x8, x16 SDRAM

Electrical Specifications – AC Operating Conditions

PDF: 09005aef8091e6d1

256Mb_sdr.pdf - Rev. N 1/10 EN 30 Micron Technology, Inc. reserves the right to change products or specifications without notice.

Functional Description

In general, 256Mb SDRAM devices (16 Meg x 4 x 4 banks, 8 Meg x 8 x 4 banks, and 4 Meg

x 16 x 4 banks) are quad-bank DRAM that operate at 3.3V and include a synchronous

interface. All signals are registered on the positive edge of the clock signal, CLK. Each of

the x4’s 67,108,864-bit banks is organized as 8192 rows by 2048 columns by 4 bits. Each

of the x8’s 67,108,864-bit banks is organized as 8192 rows by 1024 columns by 8 bits.

Each of the x16’s 67,108,864-bit banks is organized as 8192 rows by 512 columns by 16

bits.

Read and write accesses to the SDRAM are burst-oriented; accesses start at a selected

location and continue for a programmed number of locations in a programmed se-

quence. Accesses begin with the registration of an ACTIVE command, followed by a

READ or WRITE command. The address bits registered coincident with the ACTIVE com-

mand are used to select the bank and row to be accessed (BA0 and BA1 select the bank,

A[12:0] select the row). The address bits (x4: A[9:0], A11; x8: A[9:0]; x16: A[8:0]) registered

coincident with the READ or WRITE command are used to select the starting column

location for the burst access.

Prior to normal operation, the SDRAM must be initialized. The following sections pro-

vide detailed information covering device initialization, register definition, command

descriptions, and device operation.

256Mb: x4, x8, x16 SDRAM

Functional Description

PDF: 09005aef8091e6d1

256Mb_sdr.pdf - Rev. N 1/10 EN 31 Micron Technology, Inc. reserves the right to change products or specifications without notice.

Commands

The following table provides a quick reference of available commands, followed by a

written description of each command. Additional Truth Tables (Table 17 (page 38),

Table 18 (page 40), and Table 19 (page 42)) provide current state/next state informa-

tion.

Table 16: Truth Table – Commands and DQM Operation

Note 1 applies to all parameters and conditions

Name (Function) CS# RAS# CAS# WE# DQM ADDR DQ Notes

COMMAND INHIBIT (NOP) H X X X X X X

NO OPERATION (NOP) L H H H X X X

ACTIVE (select bank and activate row) L L H H X Bank/row X 2

READ (select bank and column, and start READ burst) L H L H L/H Bank/col X 3

WRITE (select bank and column, and start WRITE burst) L H L L L/H Bank/col Valid 3

BURST TERMINATE L H H L X X Active 4

PRECHARGE (Deactivate row in bank or banks) L L H L X Code X 5

AUTO REFRESH or SELF REFRESH (enter self refresh mode) L L L H X X X 6, 7

LOAD MODE REGISTER L L L L X Op-code X 8

Write enable/output enable X X X X L X Active 9

Write inhibit/output High-Z X X X X H X High-Z 9

Notes: 1. CKE is HIGH for all commands shown except SELF REFRESH.

2. A[0:n] provide row address (where An is the most significant address bit), BA0 and BA1

determine which bank is made active.

3. A[0:i] provide column address (where i = the most significant column address for a given

device configuration). A10 HIGH enables the auto precharge feature (nonpersistent),

while A10 LOW disables the auto precharge feature. BA0 and BA1 determine which

bank is being read from or written to.

4. The purpose of the BURST TERMINATE command is to stop a data burst, thus the com-

mand could coincide with data on the bus. However, the DQ column reads a “Don’t

Care” state to illustrate that the BURST TERMINATE command can occur when there is

no data present.

5. A10 LOW: BA0, BA1 determine the bank being precharged. A10 HIGH: all banks pre-

charged and BA0, BA1 are “Don’t Care.”

6. This command is AUTO REFRESH if CKE is HIGH, SELF REFRESH if CKE is LOW.

7. Internal refresh counter controls row addressing; all inputs and I/Os are “Don’t Care”

except for CKE.

8. A[11:0] define the op-code written to the mode register.

9. Activates or deactivates the DQ during WRITEs (zero-clock delay) and READs (two-clock

delay).

COMMAND INHIBIT

The COMMAND INHIBIT function prevents new commands from being executed by

the device, regardless of whether the CLK signal is enabled. The device is effectively de-

selected. Operations already in progress are not affected.

256Mb: x4, x8, x16 SDRAM

Commands

PDF: 09005aef8091e6d1

256Mb_sdr.pdf - Rev. N 1/10 EN 32 Micron Technology, Inc. reserves the right to change products or specifications without notice.

NO OPERATION (NOP)

The NO OPERATION (NOP) command is used to perform a NOP to the selected device

(CS# is LOW). This prevents unwanted commands from being registered during idle or

wait states. Operations already in progress are not affected.

LOAD MODE REGISTER (LMR)

The mode registers are loaded via inputs A[n:0] (where An is the most significant ad-

dress term), BA0, and BA1(see Mode Register (page 46)). The LOAD MODE REGISTER

command can only be issued when all banks are idle and a subsequent executable com-

mand cannot be issued until tMRD is met.

ACTIVE

The ACTIVE command is used to activate a row in a particular bank for a subsequent

access. The value on the BA0, BA1 inputs selects the bank, and the address provided

selects the row. This row remains active for accesses until a PRECHARGE command is

issued to that bank. A PRECHARGE command must be issued before opening a differ-

ent row in the same bank.

Figure 13: ACTIVE Command

CS#

WE#

CAS#

RAS#

CKE

CLK

Address Row address

Don’t Care

HIGH

BA0, BA1 Bank address

256Mb: x4, x8, x16 SDRAM

Commands

PDF: 09005aef8091e6d1

256Mb_sdr.pdf - Rev. N 1/10 EN 33 Micron Technology, Inc. reserves the right to change products or specifications without notice.

READ

The READ command is used to initiate a burst read access to an active row. The values

on the BA0 and BA1 inputs select the bank; the address provided selects the starting

column location. The value on input A10 determines whether auto precharge is used. If

auto precharge is selected, the row being accessed is precharged at the end of the READ

burst; if auto precharge is not selected, the row remains open for subsequent accesses.

Read data appears on the DQ subject to the logic level on the DQM inputs two clocks

earlier. If a given DQM signal was registered HIGH, the corresponding DQ will be High-

Z two clocks later; if the DQM signal was registered LOW, the DQ will provide valid data.

Figure 14: READ Command

CS#

WE#

CAS#

RAS#

CKE

CLK

Column address

A101

BA0, BA1

Don’t Care

HIGH

EN AP

DIS AP

Bank address

Address

Note: 1. EN AP = enable auto precharge, DIS AP = disable auto precharge.

256Mb: x4, x8, x16 SDRAM

Commands

PDF: 09005aef8091e6d1

256Mb_sdr.pdf - Rev. N 1/10 EN 34 Micron Technology, Inc. reserves the right to change products or specifications without notice.

WRITE

The WRITE command is used to initiate a burst write access to an active row. The val-

ues on the BA0 and BA1 inputs select the bank; the address provided selects the starting

column location. The value on input A10 determines whether auto precharge is used. If

auto precharge is selected, the row being accessed is precharged at the end of the write

burst; if auto precharge is not selected, the row remains open for subsequent accesses.

Input data appearing on the DQ is written to the memory array, subject to the DQM

input logic level appearing coincident with the data. If a given DQM signal is registered

LOW, the corresponding data is written to memory; if the DQM signal is registered

HIGH, the corresponding data inputs are ignored and a WRITE is not executed to that

byte/column location.

Figure 15: WRITE Command

DIS AP

EN AP

CS#

WE#

CAS#

RAS#

CKE

CLK

Column address

Don’t Care

HIGH

Bank address

Address

BA0, BA1

Valid address

A101

Note: 1. EN AP = enable auto precharge, DIS AP = disable auto precharge.

256Mb: x4, x8, x16 SDRAM

Commands

PDF: 09005aef8091e6d1

256Mb_sdr.pdf - Rev. N 1/10 EN 35 Micron Technology, Inc. reserves the right to change products or specifications without notice.

PRECHARGE

The PRECHARGE command is used to deactivate the open row in a particular bank or

the open row in all banks. The bank(s) will be available for a subsequent row access a

specified time (tRP) after the PRECHARGE command is issued. Input A10 determines

whether one or all banks are to be precharged, and in the case where only one bank is

precharged, inputs BA0 and BA1 select the bank. Otherwise BA0 and BA1 are treated as

“Don’t Care.” After a bank has been precharged, it is in the idle state and must be activa-

ted prior to any READ or WRITE commands are issued to that bank.

Figure 16: PRECHARGE Command

CS#

WE#

CAS#

RAS#

CKE

CLK

A10

Don’t Care

HIGH

All banks

Bank selected

Address

BA0, BA1 Bank address

Valid address

BURST TERMINATE

The BURST TERMINATE command is used to truncate either fixed-length or continu-

ous page bursts. The most recently registered READ or WRITE command prior to the

BURST TERMINATE command is truncated.

256Mb: x4, x8, x16 SDRAM

Commands

PDF: 09005aef8091e6d1

256Mb_sdr.pdf - Rev. N 1/10 EN 36 Micron Technology, Inc. reserves the right to change products or specifications without notice.

AUTO REFRESH

AUTO REFRESH is used during normal operation of the SDRAM and is analogous to CAS#-

BEFORE-RAS# (CBR) refresh in conventional DRAMs. This command is nonpersistent,

so it must be issued each time a refresh is required. All active banks must be precharged

prior to issuing an AUTO REFRESH command. The AUTO REFRESH command should

not be issued until the minimum tRP has been met after the PRECHARGE command, as

shown in Bank/Row Activation (page 51).

The addressing is generated by the internal refresh controller. This makes the address

bits a “Don’t Care” during an AUTO REFRESH command. Regardless of device width,

the 256Mb SDRAM requires 8192 AUTO REFRESH cycles every 64ms (commercial and

industrial) or 16ms (automotive). Providing a distributed AUTO REFRESH command ev-

ery 7.813μs (commercial and industrial) or 1.953μs (automotive) will meet the refresh

requirement and ensure that each row is refreshed. Alternatively, 8192 AUTO REFRESH

commands can be issued in a burst at the minimum cycle rate (tRFC), once every 64ms

(commercial and industrial) or 16ms (automotive).

SELF REFRESH

The SELF REFRESH command can be used to retain data in the SDRAM, even if the rest

of the system is powered-down. When in the self refresh mode, the SDRAM retains data

without external clocking.

The SELF REFRESH command is initiated like an AUTO REFRESH command except

CKE is disabled (LOW). After the SELF REFRESH command is registered, all the inputs

to the SDRAM become a “Don’t Care” with the exception of CKE, which must remain

LOW.

After self refresh mode is engaged, the SDRAM provides its own internal clocking, caus-

ing it to perform its own AUTO REFRESH cycles. The SDRAM must remain in self

refresh mode for a minimum period equal to tRAS and may remain in self refresh mode

for an indefinite period beyond that.

The procedure for exiting self refresh requires a sequence of commands. First, CLK

must be stable (stable clock is defined as a signal cycling within timing constraints speci-

fied for the clock pin) prior to CKE going back HIGH. After CKE is HIGH, the SDRAM

must have NOP commands issued (a minimum of two clocks) for tXSR because time is

required for the completion of any internal refresh in progress.

Upon exiting the self refresh mode, AUTO REFRESH commands must be issued every

7.81μs or less, as both SELF REFRESH and AUTO REFRESH utilize the row refresh counter.

Self refresh is not supported on automotive temperature (AT) devices.

256Mb: x4, x8, x16 SDRAM

Commands

PDF: 09005aef8091e6d1

256Mb_sdr.pdf - Rev. N 1/10 EN 37 Micron Technology, Inc. reserves the right to change products or specifications without notice.

Truth Tables

Table 17: Truth Table – Current State Bank n, Command to Bank n

Notes 1–6 apply to all parameters and conditions

Current State CS# RAS# CAS# WE# Command/Action Notes

Any H X X X COMMAND INHIBIT (NOP/continue previous operation)

L H H H NO OPERATION (NOP/continue previous operation)

Idle L L H H ACTIVE (select and activate row)

L L L H AUTO REFRESH 7

L L L L LOAD MODE REGISTER 7

L L H L PRECHARGE 8

Row active L H L H READ (select column and start READ burst) 9

L H L L WRITE (select column and start WRITE burst) 9

L L H L PRECHARGE (deactivate row in bank or banks) 10

Read

(auto precharge disabled)

L H L H READ (select column and start new READ burst) 9

L H L L WRITE (select column and start WRITE burst) 9

L L H L PRECHARGE (truncate READ burst, start PRECHARGE) 10

L H H L BURST TERMINATE 11

Write

(auto precharge disabled)

L H L H READ (select column and start READ burst) 9

L H L L WRITE (select column and start new WRITE burst) 9

L L H L PRECHARGE (truncate WRITE burst, start PRECHARGE) 10

L H H L BURST TERMINATE 11

Notes: 1. This table applies when CKEn-1 was HIGH and CKEn is HIGH (see Table 19 (page 42))

and after tXSR has been met (if the previous state was self refresh).

2. This table is bank-specific, except where noted (for example, the current state is for a

specific bank and the commands shown can be issued to that bank when in that state).

Exceptions are covered below.

3. Current state definitions:

Idle: The bank has been precharged, and tRP has been met.

Row active: A row in the bank has been activated, and tRCD has been met. No data bursts/

accesses and no register accesses are in progress.

Read: A READ burst has been initiated, with auto precharge disabled, and has not yet

terminated or been terminated.

Write: A WRITE burst has been initiated, with auto precharge disabled, and has not yet

terminated or been terminated.

4. The following states must not be interrupted by a command issued to the same bank.

COMMAND INHIBIT or NOP commands, or supported commands to the other bank

should be issued on any clock edge occurring during these states. Supported commands

to any other bank are determined by the bank’s current state and the conditions descri-

bed in this and the following table.

Precharging: Starts with registration of a PRECHARGE command and ends when tRP is

met. After tRP is met, the bank will be in the idle state.

Row activating: Starts with registration of an ACTIVE command and ends when tRCD is

met. After tRCD is met, the bank will be in the row active state.

256Mb: x4, x8, x16 SDRAM

Truth Tables

PDF: 09005aef8091e6d1

256Mb_sdr.pdf - Rev. N 1/10 EN 38 Micron Technology, Inc. reserves the right to change products or specifications without notice.

Read with auto precharge enabled: Starts with registration of a READ command

with auto precharge enabled and ends when tRP has been met. After tRP is met, the

bank will be in the idle state.

Write with auto precharge enabled: Starts with registration of a WRITE command

with auto precharge enabled and ends when tRP has been met. After tRP is met, the

bank will be in the idle state.

5. The following states must not be interrupted by any executable command; COMMAND

INHIBIT or NOP commands must be applied on each positive clock edge during these states.

Refreshing: Starts with registration of an AUTO REFRESH command and ends when

tRFC is met. After tRFC is met, the device will be in the all banks idle state.

Accessing mode register: Starts with registration of a LOAD MODE REGISTER com-

mand and ends when tMRD has been met. After tMRD is met, the device will be in the

all banks idle state.

Precharging all: Starts with registration of a PRECHARGE ALL command and ends

when tRP is met. After tRP is met, all banks will be in the idle state.

6. All states and sequences not shown are illegal or reserved.

7. Not bank specific; requires that all banks are idle.

8. Does not affect the state of the bank and acts as a NOP to that bank.

9. READs or WRITEs listed in the Command/Action column include READs or WRITEs with

auto precharge enabled and READs or WRITEs with auto precharge disabled.

10. May or may not be bank specific; if all banks need to be precharged, each must be in a

valid state for precharging.

11. Not bank-specific; BURST TERMINATE affects the most recent READ or WRITE burst, re-

gardless of bank.

256Mb: x4, x8, x16 SDRAM

Truth Tables

PDF: 09005aef8091e6d1

256Mb_sdr.pdf - Rev. N 1/10 EN 39 Micron Technology, Inc. reserves the right to change products or specifications without notice.

Table 18: Truth Table – Current State Bank n, Command to Bank m

Notes 1–6 apply to all parameters and conditions

Current State CS# RAS# CAS# WE# Command/Action Notes

Any H X X X COMMAND INHIBIT (NOP/continue previous operation)

L H H H NO OPERATION (NOP/continue previous operation)

Idle X X X X Any command otherwise supported for bank m

Row activating, active, or

precharging

L L H H ACTIVE (select and activate row)

L H L H READ (select column and start READ burst) 7

L H L L WRITE (select column and start WRITE burst) 7

L L H L PRECHARGE

Read

(auto precharge disabled)

L L H H ACTIVE (select and activate row)

L H L H READ (select column and start new READ burst) 7, 10

L H L L WRITE (select column and start WRITE burst) 7, 11

L L H L PRECHARGE 9

Write

(auto precharge disabled)

L L H H ACTIVE (select and activate row)

L H L H READ (select column and start READ burst) 7, 12

L H L L WRITE (select column and start new WRITE burst) 7, 13

L L H L PRECHARGE 9

Read

(with auto precharge)

L L H H ACTIVE (select and activate row)

L H L H READ (select column and start new READ burst) 7, 8, 14

L H L L WRITE (select column and start WRITE burst) 7, 8, 15

L L H L PRECHARGE 9

Write

(with auto precharge)

L L H H ACTIVE (select and activate row)

L H L H READ (select column and start READ burst) 7, 8, 16

L H L L WRITE (select column and start new WRITE burst) 7, 8, 17

L L H L PRECHARGE 9

Notes: 1. This table applies when CKEn-1 was HIGH and CKEn is HIGH (Table 19 (page 42)), and

after tXSR has been met (if the previous state was self refresh).

2. This table describes alternate bank operation, except where noted; for example, the cur-

rent state is for bank n and the commands shown can be issued to bank m, assuming

that bank m is in such a state that the given command is supported. Exceptions are cov-

ered below.

3. Current state definitions:

Idle: The bank has been precharged, and tRP has been met.

Row active: A row in the bank has been activated, and tRCD has been met. No data bursts/

accesses and no register accesses are in progress.

Read: A READ burst has been initiated, with auto precharge disabled, and has not yet

terminated or been terminated.

Write: A WRITE burst has been initiated, with auto precharge disabled, and has not yet

terminated or been terminated.

256Mb: x4, x8, x16 SDRAM

Truth Tables

PDF: 09005aef8091e6d1

256Mb_sdr.pdf - Rev. N 1/10 EN 40 Micron Technology, Inc. reserves the right to change products or specifications without notice.

Read with auto precharge enabled: Starts with registration of a READ command

with auto precharge enabled and ends when tRP has been met. After tRP is met, the

bank will be in the idle state.

Write with auto precharge enabled: Starts with registration of a WRITE command

with auto precharge enabled and ends when tRP has been met. After tRP is met, the

bank will be in the idle state.

4. AUTO REFRESH, SELF REFRESH, and LOAD MODE REGISTER commands can only be is-

sued when all banks are idle.

5. A BURST TERMINATE command cannot be issued to another bank; it applies to the bank

represented by the current state only.

6. All states and sequences not shown are illegal or reserved.

7. READs or WRITEs to bank m listed in the Command/Action column include READs or

WRITEs with auto precharge enabled and READs or WRITEs with auto precharge disabled.

8. Concurrent auto precharge: Bank n will initiate the auto precharge command when its

burst has been interrupted by bank m burst.

9. The burst in bank n continues as initiated.

10. For a READ without auto precharge interrupted by a READ (with or without auto pre-

charge), the READ to bank m will interrupt the READ on bank n, CAS latency (CL) later.

11. For a READ without auto precharge interrupted by a WRITE (with or without auto pre-

charge), the WRITE to bank m will interrupt the READ on bank n when registered. DQM

should be used one clock prior to the WRITE command to prevent bus contention.

12. For a WRITE without auto precharge interrupted by a READ (with or without auto pre-

charge), the READ to bank m will interrupt the WRITE on bank n when registered, with

the data-out appearing CL later. The last valid WRITE to bank n will be data-in regis-

tered one clock prior to the READ to bank m.

13. For a WRITE without auto precharge interrupted by a WRITE (with or without auto pre-

charge), the WRITE to bank m will interrupt the WRITE on bank n when registered. The

last valid WRITE to bank n will be data-in registered one clock prior to the READ to bank

14. For a READ with auto precharge interrupted by a READ (with or without auto pre-

charge), the READ to bank m will interrupt the READ on bank n, CL later. The PRE-

CHARGE to bank n will begin when the READ to bank m is registered.

15. For a READ with auto precharge interrupted by a WRITE (with or without auto pre-

charge), the WRITE to bank m will interrupt the READ on bank n when registered. DQM

should be used two clocks prior to the WRITE command to prevent bus contention. The

PRECHARGE to bank n will begin when the WRITE to bank m is registered.

16. For a WRITE with auto precharge interrupted by a READ (with or without auto pre-

charge), the READ to bank m will interrupt the WRITE on bank n when registered, with

the data-out appearing CL later. The PRECHARGE to bank n will begin after tWR is met,

where tWR begins when the READ to bank m is registered. The last valid WRITE bank n

will be data-in registered one clock prior to the READ to bank m.

17. For a WRITE with auto precharge interrupted by a WRITE (with or without auto pre-

charge), the WRITE to bank m will interrupt the WRITE on bank n when registered. The

PRECHARGE to bank n will begin after tWR is met, where tWR begins when the WRITE

to bank m is registered. The last valid WRITE to bank n will be data registered one clock

to the WRITE to bank m.

256Mb: x4, x8, x16 SDRAM

Truth Tables

PDF: 09005aef8091e6d1

256Mb_sdr.pdf - Rev. N 1/10 EN 41 Micron Technology, Inc. reserves the right to change products or specifications without notice.

Table 19: Truth Table – CKE

Notes 1–4 apply to all parameters and conditions

Current State CKEn-1 CKEnCommandnActionnNotes

Power-down L L X Maintain power-down

Self refresh X Maintain self refresh

Clock suspend X Maintain clock suspend

Power-down L H COMMAND INHIBIT or NOP Exit power-down 5

Self refresh COMMAND INHIBIT or NOP Exit self refresh 6

Clock suspend X Exit clock suspend 7

All banks idle H L COMMAND INHIBIT or NOP Power-down entry

All banks idle AUTO REFRESH Self refresh entry

Reading or writing VALID Clock suspend entry

H H See Table 18 (page 40).

Notes: 1. CKEn is the logic state of CKE at clock edge n; CKEn-1 was the state of CKE at the previ-

ous clock edge.

2. Current state is the state of the SDRAM immediately prior to clock edge n.

3. COMMANDn is the command registered at clock edge n, and ACTIONn is a result of COM-

MANDn.

4. All states and sequences not shown are illegal or reserved.

5. Exiting power-down at clock edge n will put the device in the all banks idle state in time

for clock edge n + 1 (provided that tCKS is met).

6. Exiting self refresh at clock edge n will put the device in the all banks idle state after

tXSR is met. COMMAND INHIBIT or NOP commands should be issued on any clock edges

occurring during the tXSR period. A minimum of two NOP commands must be provided

during the tXSR period.

7. After exiting clock suspend at clock edge n, the device will resume operation and recog-

nize the next command at clock edge n + 1.

256Mb: x4, x8, x16 SDRAM

Truth Tables

PDF: 09005aef8091e6d1

256Mb_sdr.pdf - Rev. N 1/10 EN 42 Micron Technology, Inc. reserves the right to change products or specifications without notice.

Initialization

SDRAM must be powered up and initialized in a predefined manner. Operational proce-

dures other than those specified may result in undefined operation. After power is

applied to VDD and VDDQ (simultaneously) and the clock is stable (stable clock is defined

as a signal cycling within timing constraints specified for the clock pin), the SDRAM re-

quires a 100μs delay prior to issuing any command other than a COMMAND INHIBIT

or NOP. Starting at some point during this 100μs period and continuing at least through

the end of this period, COMMAND INHIBIT or NOP commands must be applied.

After the 100μs delay has been satisfied with at least one COMMAND INHIBIT or NOP

command having been applied, a PRECHARGE command should be applied. All banks

must then be precharged, thereby placing the device in the all banks idle state.

Once in the idle state, at least two AUTO REFRESH cycles must be performed. After the

AUTO REFRESH cycles are complete, the SDRAM is ready for mode register program-

ming. Because the mode register will power up in an unknown state, it must be loaded

prior to applying any operational command. If desired, the two AUTO REFRESH com-

mands can be issued after the LMR command.

The recommended power-up sequence for SDRAM:

1. Simultaneously apply power to VDD and VDDQ.

2. Assert and hold CKE at a LVTTL logic LOW since all inputs and outputs are LVTTL-

compatible.

3. Provide stable CLOCK signal. Stable clock is defined as a signal cycling within tim-

ing constraints specified for the clock pin.

4. Wait at least 100μs prior to issuing any command other than a COMMAND INHIB-

IT or NOP.

5. Starting at some point during this 100μs period, bring CKE HIGH. Continuing at

least through the end of this period, 1 or more COMMAND INHIBIT or NOP com-

mands must be applied.

6. Perform a PRECHARGE ALL command.

7. Wait at least tRP time; during this time NOPs or DESELECT commands must be

given. All banks will complete their precharge, thereby placing the device in the all

banks idle state.

8. Issue an AUTO REFRESH command.

9. Wait at least tRFC time, during which only NOPs or COMMAND INHIBIT com-

mands are allowed.

10. Issue an AUTO REFRESH command.

11. Wait at least tRFC time, during which only NOPs or COMMAND INHIBIT com-

mands are allowed.

12. The SDRAM is now ready for mode register programming. Because the mode regis-

ter will power up in an unknown state, it should be loaded with desired bit values

prior to applying any operational command. Using the LMR command, program

the mode register. The mode register is programmed via the MODE REGISTER

SET command with BA1 = 0, BA0 = 0 and retains the stored information until it is

programmed again or the device loses power. Not programming the mode register

upon initialization will result in default settings which may not be desired. Out-

puts are guaranteed High-Z after the LMR command is issued. Outputs should be

High-Z already before the LMR command is issued.

13. Wait at least tMRD time, during which only NOP or DESELECT commands are al-

lowed.

256Mb: x4, x8, x16 SDRAM

Initialization

PDF: 09005aef8091e6d1

256Mb_sdr.pdf - Rev. N 1/10 EN 43 Micron Technology, Inc. reserves the right to change products or specifications without notice.

At this point the DRAM is ready for any valid command.

Note:

More than two AUTO REFRESH commands can be issued in the sequence. After steps 9

and 10 are complete, repeat them until the desired number of AUTO REFRESH + tRFC

loops is achieved.

256Mb: x4, x8, x16 SDRAM

Initialization

PDF: 09005aef8091e6d1

256Mb_sdr.pdf - Rev. N 1/10 EN 44 Micron Technology, Inc. reserves the right to change products or specifications without notice.

Figure 17: Initialize and Load Mode Register

tCH

tCL

tCK

CKE

COMMAND

BA0, BA1 BANK

tRFC tMRD

tRFC

AUTO REFRESH AUTO REFRESH Program Mode Register 1, 3, 4

tCMH

tCMS

Precharge

all banks

(

)(

)

(

)(

)

(

)(

)

(

)(

)

tRP

(

)(

)

(

)(

)

tCKS

Power-up:

VDD and

CLK stable

T = 100µs

MIN

PRECHARGE NOP AUTO

REFRESH NOP

LOAD MODE

(

)(

)

(

)(

)

(

)(

)

(

)(

)

(

)(

)

(

)(

)

AUTO

REFRESH

ALL

BANKS

(

)(

)

(

)(

)

(

)(

)

(

)(

)

(

)(

)

(

)(

)

High-Z

tCKH

(

)(

)

(

)(

)

DQM/

DQML, DQMU

(

)(

)

(

)(

)

(

)(

)

(

)(

)

(

)(

)

(

)(

)

(

)(

)

(

)(

)

(

)(

)

(

)(

)

(

)(

)

(

)(

)

(

)(

)

(

)(

)

(

)(

)

(

)(

)

NOP

(

)(

)

(

)(

)

A[9:0],

A[12:11] ROW

tAH 5

tAS

CODE

(

)(

)

(

)(

)

(

)(

)

(

)(

)

(

)(

)

(

)(

)

(

)(

)

(

)(

)

A10 ROW

tAH

tAS

CODE

(

)(

)

(

)(

)

(

)(

)

(

)(

)

ALL BANKS

SINGLE BANK

(

)(

)

(

)(

)

(

)(

)

(

)(

)

DON’T CARE

UNDEFINED

T0 T1 Tn + 1 To + 1 Tp + 1 Tp + 2 Tp + 3

Notes: 1. The mode register may be loaded prior to the AUTO REFRESH cycles if desired.

2. If CS is HIGH at clock HIGH time, all commands applied are NOP.

3. JEDEC and PC100 specify three clocks.

4. Outputs are guaranteed High-Z after command is issued.

5. A12 should be a LOW at tP + 1.

256Mb: x4, x8, x16 SDRAM

Initialization

PDF: 09005aef8091e6d1

256Mb_sdr.pdf - Rev. N 1/10 EN 45 Micron Technology, Inc. reserves the right to change products or specifications without notice.

Mode Register

The mode register defines the specific mode of operation, including burst length (BL),

burst type, CAS latency (CL), operating mode, and write burst mode. The mode register

is programmed via the LOAD MODE REGISTER command and retains the stored infor-

mation until it is programmed again or the device loses power.

Mode register bits M[2:0] specify the BL; M3 specifies the type of burst; M[6:4] specify

the CL; M7 and M8 specify the operating mode; M9 specifies the write burst mode; and

M10–Mn should be set to zero to ensure compatibility with future revisions. Mn + 1 and

Mn + 2 should be set to zero to select the mode register.

The mode registers must be loaded when all banks are idle, and the controller must

wait tMRD before initiating the subsequent operation. Violating either of these require-

ments will result in unspecified operation.

256Mb: x4, x8, x16 SDRAM

Mode Register

PDF: 09005aef8091e6d1

256Mb_sdr.pdf - Rev. N 1/10 EN 46 Micron Technology, Inc. reserves the right to change products or specifications without notice.

Figure 18: Mode Register Definition

M3 = 0

Reserved

Full Page

M3 = 1

Reserved

Operating Mode

Standard Operation

All other states reserved

–

Defined

–

Burst Type

Sequential

Interleaved

CAS Latency

Reserved

Burst Length

Burst LengthCAS Latency BT

A9 A7 A6 A5 A4 A3

A8 A2 A1 A0

Mode Register (Mx)

Address Bus

76543

821 0

M6-M0

M8 M7

Op Mode

A10

A11

Reserved WB

Write Burst Mode

Programmed Burst Length

Single Location Access

Program

BA1, BA0 = “0, 0”

to ensure compatibility

with future devices.

A12

12 9

256Mb: x4, x8, x16 SDRAM

Mode Register

PDF: 09005aef8091e6d1

256Mb_sdr.pdf - Rev. N 1/10 EN 47 Micron Technology, Inc. reserves the right to change products or specifications without notice.

Burst Length

Read and write accesses to the device are burst oriented, and the burst length (BL) is

programmable. The burst length determines the maximum number of column loca-

tions that can be accessed for a given READ or WRITE command. Burst lengths of 1, 2,

4, 8, or continuous locations are available for both the sequential and the interleaved

burst types, and a continuous page burst is available for the sequential type. The contin-

uous page burst is used in conjunction with the BURST TERMINATE command to

generate arbitrary burst lengths.

Reserved states should not be used, as unknown operation or incompatibility with fu-

ture versions may result.

When a READ or WRITE command is issued, a block of columns equal to the burst

length is effectively selected. All accesses for that burst take place within this block,

meaning that the burst wraps within the block when a boundary is reached. The block

is uniquely selected by A[8:1] when BL = 2, A[8:2] when BL = 4, and A[8:3] when BL = 8.

The remaining (least significant) address bit(s) is (are) used to select the starting loca-

tion within the block. Continuous page bursts wrap within the page when the boundary

is reached.

Burst Type

Accesses within a given burst can be programmed to be either sequential or interleaved;

this is referred to as the burst type and is selected via bit M3.

The ordering of accesses within a burst is determined by the burst length, the burst

type, and the starting column address.

256Mb: x4, x8, x16 SDRAM

Mode Register

PDF: 09005aef8091e6d1

256Mb_sdr.pdf - Rev. N 1/10 EN 48 Micron Technology, Inc. reserves the right to change products or specifications without notice.

Table 20: Burst Definition Table

Burst Length Starting Column Address

Order of Accesses Within a Burst

Type = Sequential Type = Interleaved

2 A0

0 0-1 0-1

1 1-0 1-0

4 A1 A0

0 0 0-1-2-3 0-1-2-3

0 1 1-2-3-0 1-0-3-2

1 0 2-3-0-1 2-3-0-1

1 1 3-0-1-2 3-2-1-0

8 A2 A1 A0

0 0 0 0-1-2-3-4-5-6-7 0-1-2-3-4-5-6-7

0 0 1 1-2-3-4-5-6-7-0 1-0-3-2-5-4-7-6

0 1 0 2-3-4-5-6-7-0-1 2-3-0-1-6-7-4-5

0 1 1 3-4-5-6-7-0-1-2 3-2-1-0-7-6-5-4

1 0 0 4-5-6-7-0-1-2-3 4-5-6-7-0-1-2-3

1 0 1 5-6-7-0-1-2-3-4 5-4-7-6-1-0-3-2

1 1 0 6-7-0-1-2-3-4-5 6-7-4-5-2-3-0-1

1 1 1 7-0-1-2-3-4-5-6 7-6-5-4-3-2-1-0

Continuous

n = A0–An/9/8 (location 0–y) Cn, Cn + 1, Cn + 2, Cn + 3...Cn - 1,

Cn...

Not supported

Notes: 1. For full-page accesses: y = 2,048 (x4); y = 1,024 (x8); y = 512 (x16).

2. For BL = 2, A1–A9, A11 (x4); A1–A9 (x8); or A1–A8 (x16) select the block-of-two burst; A0

selects the starting column within the block.

3. For BL = 4, A2–A9, A11 (x4); A2–A9 (x8); or A2–A8 (x16) select the block-of-four burst; A0–

A1 select the starting column within the block.

4. For BL = 8, A3–A9, A11 (x4); A3–A9 (x8); or A3–A8 (x16) select the block-of-eight burst;

A0–A2 select the starting column within the block.

5. For a full-page burst, the full row is selected and A0–A9, A11 (x4); A0–A9 (x8); or A0–A8

(x16) select the starting column.

6. Whenever a boundary of the block is reached within a given sequence above, the follow-

ing access wraps within the block.

7. For BL = 1, A0–A9, A11 (x4); A0–A9 (x8); or A0–A8 (x16) select the unique column to be

accessed, and mode register bit M3 is ignored.

256Mb: x4, x8, x16 SDRAM

Mode Register

PDF: 09005aef8091e6d1

256Mb_sdr.pdf - Rev. N 1/10 EN 49 Micron Technology, Inc. reserves the right to change products or specifications without notice.

CAS Latency

The CAS latency (CL) is the delay, in clock cycles, between the registration of a READ

command and the availability of the output data. The latency can be set to two or three

clocks.

If a READ command is registered at clock edge n, and the latency is m clocks, the data

will be available by clock edge n + m. The DQ start driving as a result of the clock edge

one cycle earlier (n + m - 1), and provided that the relevant access times are met, the

data is valid by clock edge n + m. For example, assuming that the clock cycle time is

such that all relevant access times are met, if a READ command is registered at T0 and

the latency is programmed to two clocks, the DQ start driving after T1 and the data is

valid by T2.

Reserved states should not be used as unknown operation or incompatibility with fu-

ture versions may result.

Figure 19: CAS Latency

CLK

T2T1 T3T0

CL = 3

tLZ

DOUT

tOH

Command NOPREAD NOP

NOP

Don’t Care Undefined

CLK

T2T1 T3T0

CL = 2

tLZ

DOUT

tOH

Command NOPREAD

tAC

NOP

Operating Mode

The normal operating mode is selected by setting M7 and M8 to zero; the other combi-

nations of values for M7 and M8 are reserved for future use. Reserved states should not

be used because unknown operation or incompatibility with future versions may result.

Write Burst Mode

When M9 = 0, the burst length programmed via M[2:0] applies to both READ and

WRITE bursts; when M9 = 1, the programmed burst length applies to READ bursts, but

write accesses are single-location (nonburst) accesses.

256Mb: x4, x8, x16 SDRAM

Mode Register

PDF: 09005aef8091e6d1

256Mb_sdr.pdf - Rev. N 1/10 EN 50 Micron Technology, Inc. reserves the right to change products or specifications without notice.

Bank/Row Activation

Before any READ or WRITE commands can be issued to a bank within the SDRAM, a

row in that bank must be opened. This is accomplished via the ACTIVE command,

which selects both the bank and the row to be activated.

After a row is opened with the ACTIVE command, a READ or WRITE command can be

issued to that row, subject to the tRCD specification. tRCD (MIN) should be divided by

the clock period and rounded up to the next whole number to determine the earliest

clock edge after the ACTIVE command on which a READ or WRITE command can be

entered. For example, a tRCD specification of 20ns with a 125 MHz clock (8ns period)

results in 2.5 clocks, rounded to 3. This is reflected in Figure 20 (page 51), which cov-

ers any case where 2 < tRCD (MIN)/tCK ≤ 3. (The same procedure is used to convert

other specification limits from time units to clock cycles.)

A subsequent ACTIVE command to a different row in the same bank can only be issued

after the previous active row has been precharged. The minimum time interval between

successive ACTIVE commands to the same bank is defined by tRC.

A subsequent ACTIVE command to another bank can be issued while the first bank is

being accessed, which results in a reduction of total row-access overhead. The mini-

mum time interval between successive ACTIVE commands to different banks is defined

by tRRD.

Figure 20: Example: Meeting tRCD (MIN) When 2 < tRCD (MIN)/tCK < 3

CLK

T2T1 T3T0

Command NOPACTIVE READ or

WRITE

NOP

RCD(MIN)

tCK tCK tCK

Don’t Care

256Mb: x4, x8, x16 SDRAM

Bank/Row Activation

PDF: 09005aef8091e6d1

256Mb_sdr.pdf - Rev. N 1/10 EN 51 Micron Technology, Inc. reserves the right to change products or specifications without notice.

READ Operation

READ bursts are initiated with a READ command, as shown in Figure 14 (page 34). The

starting column and bank addresses are provided with the READ command, and auto

precharge is either enabled or disabled for that burst access. If auto precharge is ena-

bled, the row being accessed is precharged at the completion of the burst. In the

following figures, auto precharge is disabled.

During READ bursts, the valid data-out element from the starting column address is

available following the CAS latency after the READ command. Each subsequent data-

out element will be valid by the next positive clock edge. Figure 22 (page 54) shows

general timing for each possible CAS latency setting.

Upon completion of a burst, assuming no other commands have been initiated, the DQ

signals will go to High-Z. A continuous page burst continues until terminated. At the

end of the page, it wraps to column 0 and continues.

Data from any READ burst can be truncated with a subsequent READ command, and

data from a fixed-length READ burst can be followed immediately by data from a READ

command. In either case, a continuous flow of data can be maintained. The first data

element from the new burst either follows the last element of a completed burst or the

last desired data element of a longer burst that is being truncated. The new READ com-

mand should be issued x cycles before the clock edge at which the last desired data

element is valid, where x = CL - 1. This is shown in Figure 22 (page 54) for CL2 and CL3.

SDRAM devices use a pipelined architecture and therefore do not require the 2n rule

associated with a prefetch architecture. A READ command can be initiated on any clock

cycle following a READ command. Full-speed random read accesses can be performed

to the same bank, or each subsequent READ can be performed to a different bank.

256Mb: x4, x8, x16 SDRAM

READ Operation

PDF: 09005aef8091e6d1

256Mb_sdr.pdf - Rev. N 1/10 EN 52 Micron Technology, Inc. reserves the right to change products or specifications without notice.

Figure 21: Consecutive READ Bursts

Don’t Care

CLK

DQ DOUT

T2T1 T4T3 T6T5T0

Command

Address

READ NOP NOP NOP NOP

Bank,

Col n

NOP

Bank,

Col b

DOUT

n + 1

DOUT

n + 2

DOUT

n + 3

DOUT

READ

X = 1 cycle

CL = 2

CLK

DQ DOUT

T2T1 T4T3 T6T5T0

Command

Address

READ NOP NOP NOP NOP

Bank,

Col n

NOP

Bank,

Col b

DOUT DOUT DOUT DOUT

READ NOP

CL = 3 Transitioning data

X = 2 cycles

Note: 1. Each READ command can be issued to any bank. DQM is LOW.

256Mb: x4, x8, x16 SDRAM

READ Operation

PDF: 09005aef8091e6d1

256Mb_sdr.pdf - Rev. N 1/10 EN 53 Micron Technology, Inc. reserves the right to change products or specifications without notice.

Figure 22: Random READ Accesses

CLK

T2T1 T4T3 T6T5T0

Command

Address

Don’t Care

DOUT DOUT DOUT DOUT

CLK

T2T1 T4T3 T5T0

Command

Address

READ NOP

Bank,

Col n

READ READ READ NOP

Bank,

Col a

Bank,

Col x

Bank,

Col m

READ NOP

Bank,

Col n

Bank,

Col a

READ READ READ NOP NOP

Bank,

Col x

Bank,

Col m

CL = 2

CL = 3

DOUT DOUT DOUT DOUT

Note: 1. Each READ command can be issued to any bank. DQM is LOW.

Data from any READ burst can be truncated with a subsequent WRITE command, and

data from a fixed-length READ burst can be followed immediately by data from a

WRITE command (subject to bus turnaround limitations). The WRITE burst can be initi-

ated on the clock edge immediately following the last (or last desired) data element

from the READ burst, provided that I/O contention can be avoided. In a given system

design, there is a possibility that the device driving the input data will go Low-Z before

the DQ go High-Z. In this case, at least a single-cycle delay should occur between the

last read data and the WRITE command.

The DQM input is used to avoid I/O contention, as shown in Figure 23 (page 55) and

Figure 24 (page 56). The DQM signal must be asserted (HIGH) at least two clocks prior

to the WRITE command (DQM latency is two clocks for output buffers) to suppress data-

out from the READ. After the WRITE command is registered, the DQ will go to High-Z

(or remain High-Z), regardless of the state of the DQM signal, provided the DQM was

active on the clock just prior to the WRITE command that truncated the READ com-

mand. If not, the second WRITE will be an invalid WRITE. For example, if DQM was

LOW during T4, then the WRITEs at T5 and T7 would be valid, and the WRITE at T6

would be invalid.

256Mb: x4, x8, x16 SDRAM

READ Operation

PDF: 09005aef8091e6d1

256Mb_sdr.pdf - Rev. N 1/10 EN 54 Micron Technology, Inc. reserves the right to change products or specifications without notice.

The DQM signal must be de-asserted prior to the WRITE command (DQM latency is

zero clocks for input buffers) to ensure that the written data is not masked. Figure 23

(page 55) shows where, due to the clock cycle frequency, bus contention is avoided

without having to add a NOP cycle, while Figure 24 (page 56) shows the case where an

additional NOP cycle is required.

A fixed-length READ burst may be followed by or truncated with a PRECHARGE com-

mand to the same bank, provided that auto precharge was not activated. The PRE-

CHARGE command should be issued x cycles before the clock edge at which the last

desired data element is valid, where x = CL - 1. This is shown in Figure 25 (page 56) for

each possible CL; data element n + 3 is either the last of a burst of four or the last de-

sired data element of a longer burst. Following the PRECHARGE command, a subse-

quent command to the same bank cannot be issued until tRP is met. Note that part of

the row precharge time is hidden during the access of the last data element(s).

In the case of a fixed-length burst being executed to completion, a PRECHARGE com-

mand issued at the optimum time (as described above) provides the same operation

that would result from the same fixed-length burst with auto precharge. The disadvant-

age of the PRECHARGE command is that it requires that the command and address

buses be available at the appropriate time to issue the command. The advantage of the

PRECHARGE command is that it can be used to truncate fixed-length or continuous

page bursts.

Figure 23: READ-to-WRITE

READ NOP NOP WRITE

NOP

CLK

T2T1 T4T3T0

DQM

Command

Address

Bank,

Col b

Bank,

Col n

tHZ

tCK

Don’t Care

Transitioning data

DOUT DIN

Note: 1. CL = 3. The READ command can be issued to any bank, and the WRITE command can be

to any bank. If a burst of one is used, DQM is not required.

256Mb: x4, x8, x16 SDRAM

READ Operation

PDF: 09005aef8091e6d1

256Mb_sdr.pdf - Rev. N 1/10 EN 55 Micron Technology, Inc. reserves the right to change products or specifications without notice.

Figure 24: READ-to-WRITE With Extra Clock Cycle

Don’t Care

READ NOP NOPNOP NOP

DQM

CLK

DQ DOUT

T2T1 T4T3T0

Command

Address Bank,

Col n

WRITE

DIN

Bank,

Col b

tDS

tHZ

Transitioning data

Note: 1. CL = 3. The READ command can be issued to any bank, and the WRITE command can be

to any bank.

Figure 25: READ-to-PRECHARGE

Don’t Care

CLK

T2T1 T4T3 T6T5T0

Command

Address

READ NOP NOP NOP NOPNOP PRECHARGE ACTIVE

tRP

CLK

DQ DOUT

T2T1 T4T3 T6T5T0

Command

Address

READ NOP NOP NOP NOPNOP

DOUT DOUT DOUT

PRECHARGE ACTIVE

tRP

X = 1 cycle

CL = 2

CL = 3

X = 2 cycles

Bank

Col

Bank

Row

Bank

(

or all)

Bank

Col

Bank

Row

Bank

(

or all)

Transitioning data

DOUT DOUT DOUT DOUT

Note: 1. DQM is LOW.

256Mb: x4, x8, x16 SDRAM

READ Operation

PDF: 09005aef8091e6d1

256Mb_sdr.pdf - Rev. N 1/10 EN 56 Micron Technology, Inc. reserves the right to change products or specifications without notice.

Continuous-page READ bursts can be truncated with a BURST TERMINATE command

and fixed-length READ bursts can be truncated with a BURST TERMINATE command,

provided that auto precharge was not activated. The BURST TERMINATE command

should be issued x cycles before the clock edge at which the last desired data element is

valid, where x = CL - 1. This is shown in Figure 26 (page 57) for each possible CAS

latency; data element n + 3 is the last desired data element of a longer burst.

Figure 26: Terminating a READ Burst

CLK

T2T1 T4T3 T6T5T0

Command

Address

NOP NOP NOP NOPNOP BURST

TERMINATE NOP

CLK

DQ DOUT

T2T1 T4T3 T6T5T0

Command

Address

READ NOP NOP NOPNOP

DOUT DOUT DOUT

BURST

TERMINATE NOP

X = 1 cycle

CL = 2

CL = 3

X = 2 cycles

Don’t CareTransitioning data

Bank,

Col n

READ

Bank,

Col n

DOUT DOUT DOUT DOUT

Note: 1. DQM is LOW.

256Mb: x4, x8, x16 SDRAM

READ Operation

PDF: 09005aef8091e6d1

256Mb_sdr.pdf - Rev. N 1/10 EN 57 Micron Technology, Inc. reserves the right to change products or specifications without notice.

Figure 27: Alternating Bank Read Accesses

Don’t Care Undefined

Enable auto precharge

tCH

tCL

tCK

tAC

tLZ

CLK

A10

tOH

DOUT

tCMH

tCMS

tAH

tAS

tAH

tAS

tAH

tAS

Row

tOH

DOUT

tAC

tOH

tAC

tOH

tAC

DOUT

Command

tCMH

tCMS

NOP NOPACTIVE NOP READ NOP ACTIVE

tOH

DOUT

tAC tAC

READ

Enable auto precharge

Row

ACTIVE

Row

Bank 0 Bank 0 Bank 3 Bank 3 Bank 0

CKE

tCKH

tCKS

Column mColumn b1

T0 T1 T2 T4T3 T5 T6 T7 T8

tRP - bank 0

tRAS - bank 0

tRCD - bank 0 tRCD - bank 0

CL - bank 0

tRCD - bank 3 CL - bank 3

tRC - bank 0

tRRD

BA0, BA1

DQM

Address

Note: 1. For this example, BL = 4 and CL = 2.

256Mb: x4, x8, x16 SDRAM

READ Operation

PDF: 09005aef8091e6d1

256Mb_sdr.pdf - Rev. N 1/10 EN 58 Micron Technology, Inc. reserves the right to change products or specifications without notice.

Figure 28: READ Continuous Page Burst

tCH

tCL tCK

tAC

tLZ

tRCD CAS latency

CKE

CLK

A10

tOH

DOUT

tCMH

tCMS

tAH

tAS

tAH

tAS

tAC

tOH

DOUT

Row

tHZ

tOH

DOUT

tAC

tOH

DOUT

tAC

tOH

DOUT

tAC

tOH

DOUT

(

)(

)

(

)(

)

(

)(

)

(

)(

)

(

)(

)

(

)(

)

(

)(

)

Full page completed

All locations within same row

Don’t Care

Undefined

Command

tCMH

tCMS

NOPNOP NOPACTIVE NOP READ NOP BURST TERMNOP NOP

(

)(

)

(

)(

)

NOP

(

)(

)

(

)(

)

tAH

tAS

Bank

(

)(

)

(

)(

)

Bank

tCKH

tCKS

(

)(

)

(

)(

)

(

)(

)

(

)(

)

Column m

T0 T1 T2 T4T3 T5 T6 Tn + 1 Tn + 2 Tn + 3 Tn + 4

BA0, BA1

DQM

Address

Full-page burst does not self-terminate.

Can use BURST TERMINATE command.

Note: 1. For this example, CL = 2.

256Mb: x4, x8, x16 SDRAM

READ Operation

PDF: 09005aef8091e6d1

256Mb_sdr.pdf - Rev. N 1/10 EN 59 Micron Technology, Inc. reserves the right to change products or specifications without notice.

Figure 29: READ – DQM Operation

tCH

tCL

tCK

tAC

tLZ

tRCD CL = 2

CKE

CLK

A10

tOH

DOUT

tCMH

tCMS

tAH

tAS

tAH

tAS

tAH

tAS

Row

Bank

Row

Bank

tHZ

tAC

tLZ

tOH

DOUT

tOH

DOUT

tHZ

Command

tCMH

tCMS

NOPNOPNOP NOPACTIVE NOP READ NOP NOP

Disable auto precharge

Enable auto precharge

Don’t Care

Undefined

tCKH

tCKS

Column m

T0 T1 T2 T4T3 T5 T6 T7 T8

BA0, BA1

DQM

Address

Note: 1. For this example, BL = 4 and CL = 2.

256Mb: x4, x8, x16 SDRAM

READ Operation

PDF: 09005aef8091e6d1

256Mb_sdr.pdf - Rev. N 1/10 EN 60 Micron Technology, Inc. reserves the right to change products or specifications without notice.

WRITE Operation

WRITE bursts are initiated with a WRITE command, as shown in Figure 15 (page 35).

The starting column and bank addresses are provided with the WRITE command and

auto precharge is either enabled or disabled for that access. If auto precharge is ena-

bled, the row being accessed is precharged at the completion of the burst. For the

generic WRITE commands used in the following figures, auto precharge is disabled.

During WRITE bursts, the first valid data-in element is registered coincident with the

WRITE command. Subsequent data elements are registered on each successive positive

clock edge. Upon completion of a fixed-length burst, assuming no other commands

have been initiated, the DQ will remain at High-Z and any additional input data will be

ignored (see Figure 30 (page 61)). A continuous page burst continues until termina-

ted; at the end of the page, it wraps to column 0 and continues.

Data for any WRITE burst can be truncated with a subsequent WRITE command, and

data for a fixed-length WRITE burst can be followed immediately by data for a WRITE

command. The new WRITE command can be issued on any clock following the previ-

ous WRITE command, and the data provided coincident with the new command ap-

plies to the new command (see Figure 31 (page 62)). Data n + 1 is either the last of a

burst of two or the last desired data element of a longer burst.

SDRAM devices use a pipelined architecture and therefore do not require the 2n rule

associated with a prefetch architecture. A WRITE command can be initiated on any

clock cycle following a previous WRITE command. Full-speed random write accesses

within a page can be performed to the same bank, as shown in Figure 32 (page 63), or

each subsequent WRITE can be performed to a different bank.

Figure 30: WRITE Burst

CLK

DQ DIN

T2T1 T3T0

Command

Address

NOP NOP

Don’t Care

WRITE

DIN

NOP

Bank,

Col n

Transitioning data

Note: 1. BL = 2. DQM is LOW.

256Mb: x4, x8, x16 SDRAM

WRITE Operation

PDF: 09005aef8091e6d1

256Mb_sdr.pdf - Rev. N 1/10 EN 61 Micron Technology, Inc. reserves the right to change products or specifications without notice.

Figure 31: WRITE-to-WRITE

CLK

T2T1T0

Command

Address

NOPWRITE WRITE

Bank,

Col n

Bank,

Col b

DIN DIN DIN

Don’t Care

Note: 1. DQM is LOW. Each WRITE command may be issued to any bank.

Data for any WRITE burst can be truncated with a subsequent READ command, and

data for a fixed-length WRITE burst can be followed immediately by a READ command.

After the READ command is registered, data input is ignored and WRITEs will not be

executed (see Figure 33 (page 63)). Data n + 1 is either the last of a burst of two or the

last desired data element of a longer burst.

Data for a fixed-length WRITE burst can be followed by or truncated with a PRE-

CHARGE command to the same bank, provided that auto precharge was not activated.

A continuous-page WRITE burst can be truncated with a PRECHARGE command to the

same bank. The PRECHARGE command should be issued tWR after the clock edge at

which the last desired input data element is registered. The auto precharge mode re-

quires a tWR of at least one clock with time to complete, regardless of frequency.

In addition, when truncating a WRITE burst at high clock frequencies (tCK < 15ns), the

DQM signal must be used to mask input data for the clock edge prior to and the clock

edge coincident with the PRECHARGE command (see Figure 34 (page 64)). Data n + 1

is either the last of a burst of two or the last desired data element of a longer burst. Fol-

lowing the PRECHARGE command, a subsequent command to the same bank cannot

be issued until tRP is met.

In the case of a fixed-length burst being executed to completion, a PRECHARGE com-

mand issued at the optimum time (as described above) provides the same operation

that would result from the same fixed-length burst with auto precharge. The disadvant-

age of the PRECHARGE command is that it requires that the command and address

buses be available at the appropriate time to issue the command. The advantage of the

PRECHARGE command is that it can be used to truncate fixed-length bursts or continu-

ous page bursts.

256Mb: x4, x8, x16 SDRAM

WRITE Operation

PDF: 09005aef8091e6d1

256Mb_sdr.pdf - Rev. N 1/10 EN 62 Micron Technology, Inc. reserves the right to change products or specifications without notice.

Figure 32: Random WRITE Cycles

Don’t Care

CLK

DQ DIN

T2T1 T3T0

Command

Address

WRITE

Bank,

Col n

DIN DIN DIN

WRITE WRITE WRITE

Bank,

Col a

Bank,

Col x

Bank,

Col m

Note: 1. Each WRITE command can be issued to any bank. DQM is LOW.

Figure 33: WRITE-to-READ

Don’t Care

CLK

T2T1 T3T0

Command

Address

NOPWRITE

Bank,

Col n

DIN DIN DOUT

READ NOP NOP

Bank,

Col b

NOP

DOUT

T4 T5

Note: 1. The WRITE command can be issued to any bank, and the READ command can be to any

bank. DQM is LOW. CL = 2 for illustration.

256Mb: x4, x8, x16 SDRAM

WRITE Operation

PDF: 09005aef8091e6d1

256Mb_sdr.pdf - Rev. N 1/10 EN 63 Micron Technology, Inc. reserves the right to change products or specifications without notice.

Figure 34: WRITE-to-PRECHARGE

Don’t Care

DQM

CLK

T2T1 T4T3T0

Command

Address Bank a,

Col n

NOPWRITE PRECHARGE NOPNOP

DIN DIN

ACTIVE

tRP

Bank

(a or all)

tWR

Bank a,

Row

DQM

Command

Address Bank a,

Col n

NOPWRITE PRECHARGE NOPNOP ACTIVE

tRP

Bank

(a or all)

tWR

Bank a,

Row

NOP

tWR @ tCK < 15ns

tWR @ tCK ≥ 15ns

DIN DIN

Note: 1. In this example DQM could remain LOW if the WRITE burst is a fixed length of two.

Fixed-length WRITE bursts can be truncated with the BURST TERMINATE command.

When truncating a WRITE burst, the input data applied coincident with the BURST TER-

MINATE command is ignored. The last data written (provided that DQM is LOW at that

time) will be the input data applied one clock previous to the BURST TERMINATE com-

mand. This is shown in Figure 35 (page 65), where data n is the last desired data

element of a longer burst.

256Mb: x4, x8, x16 SDRAM

WRITE Operation

PDF: 09005aef8091e6d1

256Mb_sdr.pdf - Rev. N 1/10 EN 64 Micron Technology, Inc. reserves the right to change products or specifications without notice.

Figure 35: Terminating a WRITE Burst

Don’t Care

CLK

T2T1T0

Command

Address Bank,

Col n

WRITE BURST

TERMINATE

COMMAND

DIN

Address

Data

Transitioning data

Note: 1. DQM is LOW.

256Mb: x4, x8, x16 SDRAM

WRITE Operation

PDF: 09005aef8091e6d1

256Mb_sdr.pdf - Rev. N 1/10 EN 65 Micron Technology, Inc. reserves the right to change products or specifications without notice.

Figure 36: Alternating Bank Write Accesses

Don’t Care

Enable auto precharge

tCH

tCL

tCK

CLK

A10

tCMH

tCMS

tAH

tAS

tAH

tAS

tAH

tAS

Row

Command

tCMH

tCMS

NOP NOPACTIVE NOP WRITE NOPNOP ACTIVEWRITE

Enable auto precharge

Row

ACTIVE

Row

Bank 0 Bank 0 Bank 1 Bank 1 Bank 0

CKE

tCKH

tCKS

Column mColumn b

T0 T1 T2 T4T3 T5 T6 T7 T8 T9

tRP - bank 0

tRAS - bank 0

tRCD - bank 0 tRCD - bank 0

tWR - bank 1

tWR - bank 0

tRCD - bank 1

tRC - bank 0

tRRD

BA0, BA1

DQM

Address

DIN

tDH

tDS

DIN DIN DIN

tDH

tDS tDH

tDS

DIN

tDH

tDS

DIN

tDH

tDS

DIN

tDH

tDS

DIN

tDH

tDS

Note: 1. For this example, BL = 4.

256Mb: x4, x8, x16 SDRAM

WRITE Operation

PDF: 09005aef8091e6d1

256Mb_sdr.pdf - Rev. N 1/10 EN 66 Micron Technology, Inc. reserves the right to change products or specifications without notice.

Figure 37: WRITE – Continuous Page Burst

tCH

tCL tCK

tRCD

CKE

CLK

A10

tCMS

tAH

tAS

tAH

tAS

Row

Full-page burst

does not self-terminate.

Use BURST TERMINATE

command to stop.1, 2

(

)(

)

(

)(

)

(

)(

)

(

)(

)

Full page completed Don’t Care

Command

tCMH

tCMS

NOPNOP NOPACTIVE NOP WRITE BURST TERMNOP NOP

(

)(

)

(

)(

)

(

)(

)

(

)(

)

DIN

tDH

tDS

DIN DIN DIN

tDH

tDS tDH

tDS

DIN

tDH

tDS

tAH

tAS

Bank

(

)(

)

(

)(

)

Bank

tCMH

tCKH

tCKS

(

)(

)

(

)(

)

(

)(

)

(

)(

)

(

)(

)

(

)(

)

All locations within same row

Column

T0 T1 T2 T3 T4 T5 Tn + 1 Tn + 2 Tn + 3

BA0, BA1

DQM

Address

Notes: 1. tWR must be satisfied prior to issuing a PRECHARGE command.

2. Page left open; no tRP.

256Mb: x4, x8, x16 SDRAM

WRITE Operation

PDF: 09005aef8091e6d1

256Mb_sdr.pdf - Rev. N 1/10 EN 67 Micron Technology, Inc. reserves the right to change products or specifications without notice.

Figure 38: WRITE – DQM Operation

Don’t Care

tCH

tCL

tCK

tRCD

CKE

CLK

A10

tCMS

tAH

tAS

Row

Bank

Row

Bank

Enable auto precharge

DIN

tDH

tDS

DIN DIN

tCMH

Command NOPNOP NOP

ACTIVE NOP WRITE NOPNOP

tCMS tCMH

tDH

tDS

tDH

tDS

tAH

tAS

tAH

tAS

Disable auto precharge

tCKH

tCKS

Column m

T0 T1 T2 T3 T4 T5 T6 T7

BA0, BA1

DQM

Address

Note: 1. For this example, BL = 4.

Burst Read/Single Write

The burst read/single write mode is entered by programming the write burst mode bit

(M9) in the mode register to a 1. In this mode, all WRITE commands result in the access

of a single column location (burst of one), regardless of the programmed burst length.

READ commands access columns according to the programmed burst length and se-

quence, just as in the normal mode of operation (M9 = 0).

256Mb: x4, x8, x16 SDRAM

WRITE Operation

PDF: 09005aef8091e6d1

256Mb_sdr.pdf - Rev. N 1/10 EN 68 Micron Technology, Inc. reserves the right to change products or specifications without notice.

PRECHARGE Operation

The PRECHARGE command (see Figure 16 (page 36)) is used to deactivate the open row

in a particular bank or the open row in all banks. The bank(s) will be available for a sub-

sequent row access some specified time (tRP) after the PRECHARGE command is

issued. Input A10 determines whether one or all banks are to be precharged, and in the

case where only one bank is to be precharged (A10 = LOW), inputs BA0 and BA1 select

the bank. When all banks are to be precharged (A10 = HIGH), inputs BA0 and BA1 are

treated as “Don’t Care.” After a bank has been precharged, it is in the idle state and

must be activated prior to any READ or WRITE commands being issued to that bank.

Auto Precharge

Auto precharge is a feature that performs the same individual-bank PRECHARGE func-

tion described previously, without requiring an explicit command. This is accomplish-

ed by using A10 to enable auto precharge in conjunction with a specific READ or WRITE

command. A precharge of the bank/row that is addressed with the READ or WRITE com-

mand is automatically performed upon completion of the READ or WRITE burst, except

in the continuous page burst mode where auto precharge does not apply. In the specific

case of write burst mode set to single location access with burst length set to continu-

ous, the burst length setting is the overriding setting and auto precharge does not apply.

Auto precharge is nonpersistent in that it is either enabled or disabled for each individu-

al READ or WRITE command.

Auto precharge ensures that the precharge is initiated at the earliest valid stage within a

burst. Another command cannot be issued to the same bank until the precharge time

(tRP) is completed. This is determined as if an explicit PRECHARGE command was is-

sued at the earliest possible time, as described for each burst type in the Burst Type

(page 48) section.

Micron SDRAM supports concurrent auto precharge; cases of concurrent auto pre-

charge for READs and WRITEs are defined below.

READ with auto precharge interrupted by a READ (with or without auto precharge)

A READ to bank m will interrupt a READ on bank n following the programmed CAS la-

tency. The precharge to bank n begins when the READ to bank m is registered (see

Figure 39 (page 70)).

READ with auto precharge interrupted by a WRITE (with or without auto precharge)

A WRITE to bank m will interrupt a READ on bank n when registered. DQM should be

used two clocks prior to the WRITE command to prevent bus contention. The pre-

charge to bank n begins when the WRITE to bank m is registered (see Figure 40

(page 71)).

WRITE with auto precharge interrupted by a READ (with or without auto precharge)

A READ to bank m will interrupt a WRITE on bank n when registered, with the data-out

appearing CL later. The precharge to bank n will begin after tWR is met, where tWR be-

gins when the READ to bank m is registered. The last valid WRITE to bank n will be data-

in registered one clock prior to the READ to bank m (see Figure 45 (page 76)).

WRITE with auto precharge interrupted by a WRITE (with or without auto precharge)

A WRITE to bank m will interrupt a WRITE on bank n when registered. The precharge to

bank n will begin after tWR is met, where tWR begins when the WRITE to bank m is

256Mb: x4, x8, x16 SDRAM

PRECHARGE Operation

PDF: 09005aef8091e6d1

256Mb_sdr.pdf - Rev. N 1/10 EN 69 Micron Technology, Inc. reserves the right to change products or specifications without notice.

registered. The last valid data WRITE to bank n will be data registered one clock prior to

a WRITE to bank m (see Figure 46 (page 76)).

Figure 39: READ With Auto Precharge Interrupted by a READ

Don’t Care

CLK

DQ DOUT

T2T1 T4T3 T6T5T0

Command READ - AP

Bank nNOP NOPNOPNOP

DOUT DOUT DOUT

NOP

Bank n

CL = 3 (bank m)

Bank m

Address

Idle

NOP

Bank n,

Col a

Bank m,

Col d

READ - AP

Bank m

Internal

states

Page active READ with burst of 4 Interrupt burst, precharge

Page active READ with burst of 4 Precharge

RP - bank ntRP - bank m

CL = 3 (bank n)

Note: 1. DQM is LOW.

256Mb: x4, x8, x16 SDRAM

PRECHARGE Operation

PDF: 09005aef8091e6d1

256Mb_sdr.pdf - Rev. N 1/10 EN 70 Micron Technology, Inc. reserves the right to change products or specifications without notice.

Figure 40: READ With Auto Precharge Interrupted by a WRITE

CLK

DQ DOUT

T2T1 T4T3 T6T5T0

Command NOPNOPNOPNOP

DIN

DIN DIN DIN

NOP

Bank n

Bank m

Address

Idle

NOP

DQM1

Bank n,

Col a

Bank m,

Col d

WRITE - AP

Bank m

Internal

States

Page

active READ with burst of 4 Interrupt burst, precharge

Page active WRITE with burst of 4 Write-back

RP -

bank

tWR - bank m

CL = 3 (bank n)

READ - AP

Bank n

Don’t Care

Note: 1. DQM is HIGH at T2 to prevent DOUTa + 1 from contending with DINd at T4.

256Mb: x4, x8, x16 SDRAM

PRECHARGE Operation

PDF: 09005aef8091e6d1

256Mb_sdr.pdf - Rev. N 1/10 EN 71 Micron Technology, Inc. reserves the right to change products or specifications without notice.

Figure 41: READ With Auto Precharge

tCH

tCL

tCK

tAC

tLZ

tRP

tRAS

tRCD CL = 2

tRC

CKE

CLK

A10

tOH

DOUT m

tCMH

tCMS

tAH

tAS

tAH

tAS

tAH

tAS

Row

Bank Bank

Row

Bank

tHZ

tOH

DOUT

m + 3

tAC

tOH

tAC

tOH

tAC

DOUT

m + 2

DOUT

m + 1

Command

tCMH

tCMS

NOPNOPNOP NOPACTIVE NOP READ NOP ACTIVE

Enable auto precharge

Don’t Care Undefined

tCKH

tCKS

Column m

T0 T1 T2 T4T3 T5 T6 T7 T8

BA0, BA1

DQM

Address

Note: 1. For this example, BL = 4 and CL = 2.

256Mb: x4, x8, x16 SDRAM

PRECHARGE Operation

PDF: 09005aef8091e6d1

256Mb_sdr.pdf - Rev. N 1/10 EN 72 Micron Technology, Inc. reserves the right to change products or specifications without notice.

Figure 42: READ Without Auto Precharge

tCH

tCL

tCK

tAC

tLZ

tRP

tRAS

tRCD CL = 2

tRC

CKE

CLK

A10

tOH

DOUT

tCMH

tCMS

tAH

tAS

tAH

tAS

tAH

tAS

Row

Bank Bank(s) Bank

Row

Bank

tHZ

tOH

DOUT

tAC

tOH

tAC

tOH

tAC

DOUT

Command

tCMH

tCMS

PRECHARGENOPNOP NOPACTIVE NOP READ NOP ACTIVE

Disable auto precharge Single bank

All banks

Don’t Care Undefined

tCKH

tCKS

Column m

T0 T1 T2 T4T3 T5 T6 T7 T8

BA0, BA1

DQM

Address

Note: 1. For this example, BL = 4, CL = 2, and the READ burst is followed by a manual PRECHARGE.

256Mb: x4, x8, x16 SDRAM

PRECHARGE Operation

PDF: 09005aef8091e6d1

256Mb_sdr.pdf - Rev. N 1/10 EN 73 Micron Technology, Inc. reserves the right to change products or specifications without notice.

Figure 43: Single READ With Auto Precharge

tCH

tCL

tCK

tAC tOH

tLZ

tRP

tRAS

tRCD CL = 2

tRC

CKE

CLK

A10

DOUT

tCMH

tCMS

tAH

tAS

tAH

tAS

tAH

tAS

Row

Bank Bank

Row

Bank

Command

tCMH

tCMS

NOPNOPNOP NOPACTIVE NOP READ ACTIVE

Enable auto precharge

Don’t Care Undefined

tCKH

tCKS

Column m

T0 T1 T2 T4T3 T5 T6 T7

BA0, BA1

DQM

Address

Note: 1. For this example, BL = 1 and CL = 2.

256Mb: x4, x8, x16 SDRAM

PRECHARGE Operation

PDF: 09005aef8091e6d1

256Mb_sdr.pdf - Rev. N 1/10 EN 74 Micron Technology, Inc. reserves the right to change products or specifications without notice.

Figure 44: Single READ Without Auto Precharge

All banks

tCH

tCL

tCK

tAC

tLZ

tRP

tRAS

tRCD CL = 2

tRC

CKE

CLK

A10

tOH

DOUT

tCMH

tCMS

tAH

tAS

tAH

tAS

tAH

tAS

Row

Bank Bank(s) Bank

Row

Bank

tHZ

Command

tCMH

tCMS

NOPNOPNOP PRECHARGE

ACTIVE NOP READ ACTIVE NOP

Disable auto precharge Single bank

Don’t Care

Undefined

tCKH

tCKS

Column m

T0 T1 T2 T4T3 T5 T6 T7 T8

BA0, BA1

DQM

Address

Note: 1. For this example, BL = 1, CL = 2, and the READ burst is followed by a manual PRECHARGE.

256Mb: x4, x8, x16 SDRAM

PRECHARGE Operation

PDF: 09005aef8091e6d1

256Mb_sdr.pdf - Rev. N 1/10 EN 75 Micron Technology, Inc. reserves the right to change products or specifications without notice.

Figure 45: WRITE With Auto Precharge Interrupted by a READ

Don’t Care

CLK

T2T1 T4T3 T6T5T0

Command WRITE - AP

Bank nNOPNOPNOPNOP

DIN

NOP NOP

Bank n

Bank m

Address Bank n,

Col a

Bank m,

Col d

READ - AP

Bank m

Internal

States

Page active WRITE with burst of 4 Interrupt burst, write-back Precharge

Page active READ with burst of 4

tRP - bank m

DOUT DOUT

CL = 3 (bank m)

RP - bank n

WR - bank n

Note: 1. DQM is LOW.

Figure 46: WRITE With Auto Precharge Interrupted by a WRITE

Don’t Care

CLK

T2T1 T4T3 T6T5T0

Command WRITE - AP

Bank nNOPNOPNOPNOP

DIN

DIN DIN

DIN DIN DIN

NOP

Bank n

Bank m

Address

NOP

Bank n,

Col a

Bank m,

Col d

WRITE - AP

Bank m

Internal

States

Page active WRITE with burst of 4 Interrupt burst, write-back Precharge

Page active WRITE with burst of 4 Write-back

WR - bank ntRP - bank n

tWR - bank m

Note: 1. DQM is LOW.

256Mb: x4, x8, x16 SDRAM

PRECHARGE Operation

PDF: 09005aef8091e6d1

256Mb_sdr.pdf - Rev. N 1/10 EN 76 Micron Technology, Inc. reserves the right to change products or specifications without notice.

Figure 47: WRITE With Auto Precharge

Enable auto precharge

tCH

tCL

tCK

tRP

tRAS

tRCD

tRC

CKE

CLK

A10

tCMH

tCMS

tAH

tAS

Row

Bank

Row

Bank

tWR

Don’t Care

DIN

tDH

tDS

DIN DIN DIN

Command

CMH

CMS

NOPNOP NOPACTIVE NOP WRITE NOPNOP NOP

Row

Bank

Row

tAH

tAS

tAH

tAS

tDH

tDS tDH

tDS

tCKH

tCKS

Column m

T0 T1 T2 T4T3 T5 T6 T7 T8 T9

DQM

BA0, BA1

Address

ACTIVE

Note: 1. For this example, BL = 4.

256Mb: x4, x8, x16 SDRAM

PRECHARGE Operation

PDF: 09005aef8091e6d1

256Mb_sdr.pdf - Rev. N 1/10 EN 77 Micron Technology, Inc. reserves the right to change products or specifications without notice.

Figure 48: WRITE Without Auto Precharge

Disable auto precharge

All banks

tCH

tCL

tCK

tRP

tRAS

tRCD

tRC

CKE

CLK

A10

tCMH

tCMS

tAH

tAS

Row

Bank Bank

Row

Bank

tWR

Don’t Care

DIN

tDH

tDS

DIN DIN DIN

Command

CMH

CMS

NOPNOP NOPACTIVE NOP WRITE PRECHARGENOP NOP

Row

Bank

Row

tAH

tAS

tAH

tAS

tDH

tDS tDH

tDS

Single bank

tCKH

tCKS

Column m

T0 T1 T2 T4T3 T5 T6 T7 T8 T9

DQM

BA0, BA1

Address

ACTIVE

Note: 1. For this example, BL = 4 and the WRITE burst is followed by a manual PRECHARGE.

256Mb: x4, x8, x16 SDRAM

PRECHARGE Operation

PDF: 09005aef8091e6d1

256Mb_sdr.pdf - Rev. N 1/10 EN 78 Micron Technology, Inc. reserves the right to change products or specifications without notice.

Figure 49: Single WRITE With Auto Precharge

Enable auto precharge

tCH

tCL

tCK

tRP

tRAS

tRCD

tRC

CKE

CLK

A10

tCMH

tCMS

tAH

tAS

Row

Bank

Row

Bank

tWR

Don’t Care

DIN

tDH

tDS

Command

CMH

CMS

NOPNOP NOPACTIVE NOP WRITE NOP NOP

Row

Bank

Row

tAH

tAS

tAH

tAS

tCKH

tCKS

Column m

T0 T1 T2 T4T3 T5 T6 T7 T8

DQM

BA0, BA1

Address

ACTIVE

Note: 1. For this example, BL = 1.

256Mb: x4, x8, x16 SDRAM

PRECHARGE Operation

PDF: 09005aef8091e6d1

256Mb_sdr.pdf - Rev. N 1/10 EN 79 Micron Technology, Inc. reserves the right to change products or specifications without notice.

Figure 50: Single WRITE Without Auto Precharge

tCH

tCL

tCK

tRP

tRAS

tRCD tWR

tRC

CKE

CLK

A10

tCMH

tCMS

tAH

tAS

tAH

tAS

tAH

tAS

Row

Bank Bank Bank

Row

Bank

Command

tCMH

tCMS

NOPNOPNOP PRECHARGEACTIVE NOP WRITE ACTIVE NOP

Disable auto precharge

Don’t Care

tCKH

tCKS

Column m

T0 T1 T2 T4T3 T5 T6 T7 T8

BA0, BA1

DQM

Address

DIN

tDH

tDS

All banks

Single bank

Note: 1. For this example, BL = 1 and the WRITE burst is followed by a manual PRECHARGE.

256Mb: x4, x8, x16 SDRAM

PRECHARGE Operation

PDF: 09005aef8091e6d1

256Mb_sdr.pdf - Rev. N 1/10 EN 80 Micron Technology, Inc. reserves the right to change products or specifications without notice.

AUTO REFRESH Operation

The AUTO REFRESH command is used during normal operation of the device to refresh

the contents of the array. This command is nonpersistent, so it must be issued each

time a refresh is required. All active banks must be precharged prior to issuing an AUTO

REFRESH command. The AUTO REFRESH command should not be issued until the min-

imum tRP is met following the PRECHARGE command. Addressing is generated by the

internal refresh controller. This makes the address bits “Don’t Care” during an AUTO

REFRESH command.

After the AUTO REFRESH command is initiated, it must not be interrupted by any exe-

cutable command until tRFC has been met. During tRFC time, COMMAND INHIBIT or

NOP commands must be issued on each positive edge of the clock. The SDRAM re-

quires that every row be refreshed each tREF period. Providing a distributed AUTO

REFRESH command—calculated by dividing the refresh period (tREF) by the number of

rows to be refreshed—meets the timing requirement and ensures that each row is re-

freshed. Alternatively, to satisfy the refresh requirement a burst refresh can be em-

ployed after every tREF period by issuing consecutive AUTO REFRESH commands for

the number of rows to be refreshed at the minimum cycle rate (tRFC).

256Mb: x4, x8, x16 SDRAM

AUTO REFRESH Operation

PDF: 09005aef8091e6d1

256Mb_sdr.pdf - Rev. N 1/10 EN 81 Micron Technology, Inc. reserves the right to change products or specifications without notice.

Figure 51: Auto Refresh Mode

All banks

Don’t Care

tCH

tCL

tCK

CKE

CLK

tRFC

(

)(

)

(

)(

)

tRP

(

)(

)

(

)(

)

Command

tCMH

tCMS

NOPNOP

(

)(

)

(

)(

)

Bank

ACTIVE

AUTO

REFRESH

(

)(

)

(

)(

)

NOPNOPPRECHARGE

Precharge all

active banks

AUTO

REFRESH

tRFC

High-Z

Bank(s)

(

)(

)

(

)(

)

(

)(

)

(

)(

)

tAH

tAS

tCKH

tCKS

NOP

(

)(

)

(

)(

)

(

)(

)

(

)(

)

Row

(

)(

)

(

)(

)

Single bank

A10

Row

(

)(

)

(

)(

)

(

)(

)

(

)(

)

(

)(

)

(

)(

)

(

)(

)

(

)(

)

T0 T1 T2 Tn + 1 To + 1

BA0, BA1

Address

DQM

(

)(

)

(

)(

)

Note: 1. Back-to-back AUTO REFRESH commands are not required.

256Mb: x4, x8, x16 SDRAM

AUTO REFRESH Operation

PDF: 09005aef8091e6d1

256Mb_sdr.pdf - Rev. N 1/10 EN 82 Micron Technology, Inc. reserves the right to change products or specifications without notice.

SELF REFRESH Operation

The self refresh mode can be used to retain data in the device, even when the rest of the

system is powered down. When in self refresh mode, the device retains data without

external clocking. The SELF REFRESH command is initiated like an AUTO REFRESH

command, except CKE is disabled (LOW). After the SELF REFRESH command is regis-

tered, all the inputs to the device become “Don’t Care” with the exception of CKE,

which must remain LOW.

After self refresh mode is engaged, the device provides its own internal clocking, ena-

bling it to perform its own AUTO REFRESH cycles. The device must remain in self

refresh mode for a minimum period equal to tRAS and remains in self refresh mode for

an indefinite period beyond that.

The procedure for exiting self refresh requires a sequence of commands. First, CLK

must be stable prior to CKE going back HIGH. (Stable clock is defined as a signal cycling

within timing constraints specified for the clock ball.) After CKE is HIGH, the device

must have NOP commands issued for a minimum of two clocks for tXSR because time is

required for the completion of any internal refresh in progress.

Upon exiting the self refresh mode, AUTO REFRESH commands must be issued accord-

ing to the distributed refresh rate (tREF/refresh row count) as both SELF REFRESH and

AUTO REFRESH utilize the row refresh counter.

256Mb: x4, x8, x16 SDRAM

SELF REFRESH Operation

PDF: 09005aef8091e6d1

256Mb_sdr.pdf - Rev. N 1/10 EN 83 Micron Technology, Inc. reserves the right to change products or specifications without notice.

Figure 52: Self Refresh Mode

All banks

tCH

tCL

tRP

CKE

CLK

Enter self refresh mode

Precharge all

active banks

tXSR

CLK stable prior to exiting

self refresh mode

Exit self refresh mode

(Restart refresh time base)

(

)(

)

(

)(

)

Don’t Care

Command

tCMH

tCMS

AUTO

REFRESH

PRECHARGE NOP NOP

Bank(s)

High-Z

tCKS

tAH

tAS

AUTO

REFRESH

tCKH

tCKS

A10

T0 T1 T2 Tn + 1 To + 1 To + 2

BA0, BA1

DQM

Address

(

)(

)

(

)(

)

(

)(

)

(

)(

)

(

)(

)

(

)(

)

(

)(

)

(

)(

)

(

)(

)

(

)(

)

(

)(

)

(

)(

)

(

)(

)

(

)(

)

(

)(

)

(

)(

)

(

)(

)

(

)(

)

(

)(

)

(

)(

)

(

)(

)

(

)(

)

(

)(

)

(

)(

)

(

)(

)

(

)(

)

Single bank

Note: 1. Each AUTO REFRESH command performs a REFRESH cycle. Back-to-back commands are

not required.

256Mb: x4, x8, x16 SDRAM

SELF REFRESH Operation

PDF: 09005aef8091e6d1

256Mb_sdr.pdf - Rev. N 1/10 EN 84 Micron Technology, Inc. reserves the right to change products or specifications without notice.

Power-Down

Power-down occurs if CKE is registered LOW coincident with a NOP or COMMAND IN-

HIBIT when no accesses are in progress. If power-down occurs when all banks are idle,

this mode is referred to as precharge power-down; if power-down occurs when there is

a row active in any bank, this mode is referred to as active power-down. Entering power-

down deactivates the input and output buffers, excluding CKE, for maximum power

savings while in standby. The device cannot remain in the power-down state longer

than the refresh period (64ms) because no REFRESH operations are performed in this

mode.

The power-down state is exited by registering a NOP or COMMAND INHIBIT with CKE

HIGH at the desired clock edge (meeting tCKS).

Figure 53: Power-Down Mode

All banks

tCH

tCL

tCK

Two clock cycles

CKE

CLK

All banks idle, enter

power-down mode

Precharge all

active banks

Input buffers gated off

while in power-down mode

Exit power-down mode

(

)(

)

Don’t Care

tCKS tCKS

Command

tCMH

tCMS

PRECHARGE NOP NOP ACTIVENOP

(

)(

)

(

)(

)

All banks idle

BA0, BA1 Bank

Bank(s)

(

)(

)

(

)(

)

High-Z

tAH

tAS

tCKH

tCKS

DQM

(

)(

)

(

)(

)

(

)(

)

(

)(

)

Address Row

(

)(

)

(

)(

)

Single bank

A10 Row

(

)(

)

(

)(

)

T0 T1 T2 Tn + 1 Tn + 2

(

)(

)

Note: 1. Violating refresh requirements during power-down may result in a loss of data.

256Mb: x4, x8, x16 SDRAM

Power-Down

PDF: 09005aef8091e6d1

256Mb_sdr.pdf - Rev. N 1/10 EN 85 Micron Technology, Inc. reserves the right to change products or specifications without notice.

Clock Suspend

The clock suspend mode occurs when a column access/burst is in progress and CKE is

registered LOW. In the clock suspend mode, the internal clock is deactivated, freezing

the synchronous logic.

For each positive clock edge on which CKE is sampled LOW, the next internal positive

clock edge is suspended. Any command or data present on the input balls when an in-

ternal clock edge is suspended will be ignored; any data present on the DQ balls

remains driven; and burst counters are not incremented, as long as the clock is suspended.

Exit clock suspend mode by registering CKE HIGH; the internal clock and related opera-

tion will resume on the subsequent positive clock edge.

Figure 54: Clock Suspend During WRITE Burst

Don’t Care

DIN

Command

Address

WRITE

Bank,

Col n

DIN

NOPNOP

CLK

T2T1 T4T3 T5T0

CKE

Internal

clock

NOP

DIN DIN

Note: 1. For this example, BL = 4 or greater, and DQM is LOW.

256Mb: x4, x8, x16 SDRAM

Clock Suspend

PDF: 09005aef8091e6d1

256Mb_sdr.pdf - Rev. N 1/10 EN 86 Micron Technology, Inc. reserves the right to change products or specifications without notice.

Figure 55: Clock Suspend During READ Burst

Don’t Care

CLK

DQ DOUT

T2T1 T4T3 T6T5T0

Command

Address

READ NOP NOP NOP

Bank,

Col n

NOP

DOUT DOUT DOUT

CKE

Internal

clock

NOP

Note: 1. For this example, CL = 2, BL = 4 or greater, and DQM is LOW.

256Mb: x4, x8, x16 SDRAM

Clock Suspend

PDF: 09005aef8091e6d1

256Mb_sdr.pdf - Rev. N 1/10 EN 87 Micron Technology, Inc. reserves the right to change products or specifications without notice.

Figure 56: Clock Suspend Mode

tCH

tCL

tCK

tAC

tLZ

DQM

CLK

A10

tOH

DOUT

tAH

tAS

tAH

tAS

tAH

tAS

Bank

tDH

DIN

tAC

tHZ

DOUT

Command

tCMH

tCMS

NOPNOP NOP NOPNOPREAD WRITE

Don’t Care Undefined

CKE

tCKS tCKH

Bank

Column m

tDS

DIN

NOP

tCKH

tCKS

tCMH

tCMS

Column e

T0 T1 T2 T3 T4 T5 T6 T7 T8 T9

BA0, BA1

Address

Note: 1. For this example, BL = 2, CL = 3, and auto precharge is disabled.

256Mb: x4, x8, x16 SDRAM

Clock Suspend

PDF: 09005aef8091e6d1

256Mb_sdr.pdf - Rev. N 1/10 EN 88 Micron Technology, Inc. reserves the right to change products or specifications without notice.

Revision History

Rev. N – 1/10

•Updated format.

•Used LPSDR as base and replaced with SDR-specific information as needed.

Rev. M – 11/08

•Added Automotive Temperature documentation to datasheet:

–Front-page Options table.

–General Description section, Automotive Temperature sub-section.

–Commands section, Auto Refresh sub-section.

–Commands section, Self Refresh sub-section.

–Electrical Specifications section, Absolute Maximum Ratings table.

–Electrical Specifications section, Temperature Limits table.

–Electrical Specifications section, IDD Specifications and Conditions (-6A).

–Electrical Specifications section, IDD Specifications and Conditions (-7E, -75).

–Electrical Specifications section, Electrical Characteristics and Recommended

AC Operating Conditions (-6A) table.

–Electrical Specifications section, Electrical Characteristics and Recommended

AC Operating Conditions (-7E, -75) table.

–Electrical Specifications section, note "The minimum specifications are used on-

ly to indicate cycle time at which proper operation over the full temperature

range is ensured..."

–Timing Diagrams section, Self Refresh Mode diagram, added note, "Self refresh

mode not supported on automotive temperature (AT) devices."

Rev. L – 8/07

•Changed heading from 16, 8, and 4 Megs to 64, 32, and 16 Megs in Features section,

Address Table table.

•Added FBGA and VFBGA package dimensions to Features section, Options table.

•Changed order of packages to show 54-ball packages after 60-ball packages in Fea-

tures section, Options table.

•Changed DQMU to DQML in Symbol column of 54-Pin TSOP Descriptions table.

•Combined 54-Ball FBGA Description table and 60-Ball FBGA Description table into

one table, 54-Ball and 60-Ball FBGA Description table.

•Removed duplicate content for Burst Type and CAS Latency (CL) in Register Defini-

tion section.

•Reworded table sub-title notes for Truth Table 1 – Commands and DQM Operation

table.

•Changed VALID to WRITE or NOP in Command column of Truth Table 2 – CKE table.

•Reworded table sub-title notes for Truth Table 2 – CKE, Truth Table 3 – Current State

Bank n, Command to Bank n, and Truth Table 4 – Current State Bank n, Command to

Bank m tables.

•Moved Electrical Characteristics and Recommended AC Operating Conditions (-6A)

and IDD Specifications and Conditions (-6A) tables from addendum to Electrical Spec-

ifications section.

256Mb: x4, x8, x16 SDRAM

Revision History

PDF: 09005aef8091e6d1

256Mb_sdr.pdf - Rev. N 1/10 EN 89 Micron Technology, Inc. reserves the right to change products or specifications without notice.

•Reworded table sub-title notes for DC Electrical Characteristics and Operating Char-

acteristics, IDD Specifications and Conditions (-6A), IDD Specifications and Conditions

(-7E, -75), Capacitance, Electrical Characteristics and Recommended AC Operating

Conditions (-6A), and Electrical Characteristics and Recommended AC Operating Con-

ditions (-7E, -75) tables.

•Moved AC Functional Characteristics (-6A) table from addendum to Electrical Specifi-

cations section.

•Reworded table sub-title notes for AC Functional Characteristics (-6A) and AC Func-

tional Characteristics (-7E, -75) tables.

Rev. K – 2/07

•Corrected MDM numbers.

•Re-created PDF; text in the .fm file did not show in the PDF.

Rev. K – 6/06

•Updated template.

•Removed PC66.

•Added -6A.

Rev. J – 3/05

•Deleted note "contact factory for availability" from Options.

Rev. H – 2/05

•Corrected "Bank 1" to "Bank 3," then-page 49.

Rev. H – 10/04

•Added Die Revision to Options.

•Changed package drawing for the Y16A to Y16Y cross over, then-page 61.

Rev. G – 8/03

•Change blue and green color to match.

•Added Pb-free packages to front page.

•Added Pb part numbers to then-page 4.

•Changed wording to VDDQ and VSSQ on then-pages 10 and 11.

•Added Note 3 to Self Refresh Mode on then-page 53.

•Added Note 3 to package drawings on then-pages 60 and 61.

Rev. F – 1/03

•Corrected E2 by removing sv on then-page 3.

•Corrected 54-ball pins G3, H9, G2, and G1 on then-page 10.

•Added transitioning data to DQ lines in Figures 7-27 on then-pages 20-30.

•Added note 37 to then-page 39.

•Updated mech drawing for 54-pin TSOP on then-page 59.

•Update mech drawing for FG Package on then-page 61.

256Mb: x4, x8, x16 SDRAM

Revision History

PDF: 09005aef8091e6d1

256Mb_sdr.pdf - Rev. N 1/10 EN 90 Micron Technology, Inc. reserves the right to change products or specifications without notice.

Rev. E – 3/02

•Added 54-ball FBGA package information to front page.

•Added 54-ball FBGA pinout drawing to then-page 3.

•Added 54-ball FBGA package part numbers to then-page 4.

•Added 54-ball FBGA pin descriptions to then-page 10.

•Updated DQM information in 60-ball FGBA pin descriptions on then-page 11.

•Added 54-ball FGBA mech drawing to then-page 59.

Rev. D – 7/01

•Removed Preliminary status.

•Updated x4 and x8 FBGA row label from Q to R on then-page 2.

•Moved "(to state (A10 LOW})" on then-page 8.

•Updated IDD(MAX) Specifications to reflect 71G power edits on then-page 33:

–IDD1 from 170/160 to 130/120 for -7E/-75.

–IDD3 from 60/60 to 45/40 for -7E/-75.

–IDD4 from 160/160 to 130/130 for -7E/-75.

–IDD5 from 340/320 to 285/270 for -7E/-75.

–IDD6 from 4/4 to 3.5/3.5 for -7E/-75.

–IDD7 from 3/3 to 2.5/2.5 for -7E/-75.

–IDD7 (low power) from 2/2 to 1.5/1.5 for -7E/-75.

•Added Capacitance table for FBGA to then-page 34.

•Added notes 34-36 for FBGA capacitance (MIN) values different from PC133 on then-

page 36.

•Changed note 9 and 11 VIH(MIN)-VIL (MAX) test conditions from 0V-3V to 0.8V- 2.0V with

1.4V reference level.

•Corrected Initialization waveform (tCMS and tCMH reversed) on then-page 37.

Rev. C – 3/01

•Added "FB" FBGA package for x4- and x8-only configurations on then-pages 1 and 3.

•Added new page with FBGA pinout for x4 and x8 configurations on then-page 2.

•Removed -8E speed grade reference on then-pages 1, 11, and 33-55.

•Updated tOH(MIN) value from 2.7ns to 3ns on then-pages 34, 39, 42-48.

•Updated Mode Register for A12 from unused to reserved on then-page 10.

•Changed tRC to tRFC for burst AUTO REFRESH commands on then-page 14.

•Updated MAX -7E/ -75 IDD5 from 300/300 to 340/320 respectively on then-page 33.

•Added reference "notes appear on page 36" on then-pages 33-35.

•Removed temp reference and added note 5 to all tables.

•Note 21 updated for tCK=ns units vs. MHz reference.

•Updated "Don't Care" state of the SELF REFRESH MODE diagram on then-page 41.

•Updated A0-A11 to A0-A9, A11 as A10 is isolated for AP.

•Updated Single READ w/o AP to include note 3 at T3 and T4 NOP cmds on then-page

44.

•Updated Write w/o AP to show tWR = 2 clks and updated note 2 to <Dinm+3> on then-

page 49.

256Mb: x4, x8, x16 SDRAM

Revision History

PDF: 09005aef8091e6d1

256Mb_sdr.pdf - Rev. N 1/10 EN 91 Micron Technology, Inc. reserves the right to change products or specifications without notice.

•Updated diagram to correct tWR/tRP to be centered around the end of tRAS on then-

page 50.

•Updated single write with AP, T3 to note 4, T4 to note 3, and tWR to note 2 on then-

page 52.

•Updated alternating bank write access, aligned tWR and tRP to T7 center on then-

page 53.

•Added new page with "FB" FBGA mechanical diagram as then-page 57.

•Added new page for FBGA marking decoder as then-page 58.

Rev. B – 10/00

•Removed all -7 speed grade references and timing information on then-pages 1,10,

and 32-35.

•Added (0°C ≤ TA ≤ +70°C) range to IDD spec table and AC tables on then-pages 32-34.

•Changed -7 to -7E and updated any previous -7 specs to -7E specs on then-pages 36-54.

•Added notation 3 to 8E reference on front page.

•Added text under AUTO REFRESH paragraph on then-page 13, "All active banks must

be PRECHARGED prior to issuing an AUTO REFRESH command. The AUTO RE-

FRESH command should not be issued until the minimum tRP has been met after the

PRECHARGE command as shown in the operations section."

•Changed "either" to "any" under Power-Down paragraph, 2nd sentence, on then-

page 23.

•For IDD Specifications and Conditions table:

–Removed any "CAS latency = 3" or "CL = 3" reference under the parameter/con-

dition column, as this became defined in notes 18 and 32 on then-page 32.

–Updated IDD specification table values from TBD to new values.

–Updated IDD 3 -8E, 75, -7E values to 55mA, 60mA, 60mA, respectively.

–IDD5 and IDD6 parameters changed from tRC to tRFC.

•On then-page 35:

–Note 11, changed VIL(MIN) to VIH(MIN).

–Note 18, changed to "IDD current will increase or decrease in a proportional

amount by the amount the frequency is altered for the test condition."

–Note 32, changed to "For -8E, CL=2 and t CK=10ns; For -75, CL=3 and t CK=7.5ns;

For -7E, CL=2, t CK=7.5ns."

–Removed reference to notes 3 through 8 in TSOP package dimensions.

•Removed notes 3 through 8 on then-page 55, as they apply only to the "B4" version of

64Mb SDR.

•Changed from Advanced to Preliminary.

Rev. A – 11/99

•Initial release.

8000 S. Federal Way, P.O. Box 6, Boise, ID 83707-0006, Tel: 208-368-3900

www.micron.com/productsupport Customer Comment Line: 800-932-4992

Micron and the Micron logo are trademarks of Micron Technology, Inc.

All other trademarks are the property of their respective owners.

This data sheet contains minimum and maximum limits specified over the power supply and temperature range set forth herein.

Although considered final, these specifications are subject to change, as further product development and data characterization some-

times occur.

256Mb: x4, x8, x16 SDRAM

Revision History

PDF: 09005aef8091e6d1

256Mb_sdr.pdf - Rev. N 1/10 EN 92 Micron Technology, Inc. reserves the right to change products or specifications without notice.