AT89C52-16PC - Atmel Corporation

4-61

68PLCC

P1.0 (T2)

VCC

P1.1 (T2 EX)

P0.0 (AD0)

P1.2

ALE/PROG

(RD) P3.7

XTAL1

EA/VPP

(WR) P3.6

GND

(RXD) P3.0

P0.7 (AD7)

P2.6 (A14)

P0.6 (AD6)

P0.5 (AD5)

P0.4 (AD4)

P0.3 (AD3)

P0.2 (AD2)

P1.3

P0.1 (AD1)

PSEN

XTAL2

(INT0) P3.2

(TXD) P3.1

(T1) P3.5

(INT1) P3.3

(T0) P3.4 P2.7 (A15)

(A11) P2.3

(A12) P2.4

(A10) P2.2

(A9) P2.1

(A8) P2.0

RST

INDEX

CORNER

P2.5 (A13)

43 40

65444

25 28

20 24

17 29

P1.4

P1.5

P1.6

P1.7

Features

•Compatible with MCS-51™ Products

•8K Bytes of In-System Reprogrammable Flash Memory

– Endurance: 1,000 Write/Erase Cycles

•Fully Static Operation: 0 Hz to 24 MHz

•Three-Level Program Memory Lock

•256 x 8-Bit Internal RAM

•32 Programmable I/O Lines

•Three 16-Bit Timer/Counters

•Eight Interrupt Sources

•Programmable Serial Channel

•Low Power Idle and Power Down Modes

Description

The AT89C52 is a low-power, high-performance CMOS 8-bit microcomputer with 8K

bytes of Flash pro grammab le and er asab le read onl y memory (PERO M). The de vice

is manufactured using Atmel’s high density nonvolatile memory technology and is

compatib le with th e industr y standar d 80C51 an d 80C52 in struction set and p inout.

The on-chip Flash allows the program memory to be reprogrammed in-system or by a

conventional nonvolatile memory programmer. By combining a versatile 8-bit CPU

with Fla sh on a monoli thic chip, the A tmel AT89C5 2 is a powerful mi crocomputer

which p rovi des a highly flex ib le and c os t e ffec ti ve s olu tio n to m any e mbe dde d c on tro l

applications.

0313F-A–12/97

8-Bit

Microcontroller

with 8K Bytes

Flash

AT89C52

PDIP

(T2) P1.0

(T2 EX) P1.1

P0.0 (AD0)

P1.2

(INT0) P3.2

ALE/PROG

(RD) P3.7 P2.3 (A11)

(TXD) P3.1

EA/VPP

(WR) P3.6 P2.4 (A12)

(RXD) P3.0

P0.7 (AD7)

(T1) P3.5 P2.6 (A14)

RST

P0.6 (AD6)

P0.5 (AD5)

P0.4 (AD4)

P0.3 (AD3)

P0.2 (AD2)

P1.3

P0.1 (AD1)

(INT1) P3.3

PSEN

XTAL2 P2.2 (A10)

(T0) P3.4 P2.7 (A15)

XTAL1 P2.1 (A9)

GND P2.0 (A8)

P2.5 (A13)

P1.4

P1.5

P1.6

P1.7

Pin Configurations

PQFP/TQFP

INDEX

CORNER

P1.0 (T2)

VCC

P1.1 (T2 EX)

P1.2

P1.3

43 40

18192021

121314151617

3837

3635 33

PSEN

XTAL1

GND

XTAL2

GND

P0.0 (AD0)

ALE/PROG

(RD) P3.7

EA/VPP

(WR) P3.6

(RXD) P3.0

P0.7 (AD7)

P2.6 (A14)

P0.6 (AD6)

P0.5 (AD5)

P0.4 (AD4)

P0.3 (AD3)

P0.2 (AD2)

P0.1 (AD1)

(INT0) P3.2

(TXD) P3.1

(T1) P3.5

(INT1) P3.3

(T0) P3.4 P2.7 (A15)

(A11) P2.3

(A12) P2.4

(A10) P2.2

(A9) P2.1

(A8) P2.0

RST

P2.5 (A13)

P1.4

P1.5

P1.6

P1.7

(continued)

AT89C52

4-62

Block Diagram

PORT 2 DRIVERS

PORT 2

LATCH

P2.0 - P2.7

FLASH

PORT 0

LATCH

RAM

PROGRAM

ADDRESS

BUFFER

INCREMENTER

PROGRAM

COUNTER

DPTR

RAM ADDR.

INSTRUCTION

INTERRUPT, SERIAL PORT,

AND TIMER BLOCKS

STACK

POINTER

ACC

TMP2 TMP1

ALU

PSW

TIMING

AND

CONTROL

PORT 3

LATCH

PORT 3 DRIVERS

P3.0 - P3.7

PORT 1

LATCH

PORT 1 DRIVERS

P1.0 - P1.7

OSC

GND

VCC

PSEN

ALE/PROG

EA / VPP

RST

PORT 0 DRIVERS

P0.0 - P0.7

AT89C52

4-63

The AT89 C52 provi des the fo llowi ng stan dard feat ures : 8K

bytes of Fl as h, 2 56 by tes o f RA M, 32 I/O lin es , th ree 1 6-bi t

timer/cou nters, a six -vector two -level inter rupt architec ture,

a full dup lex serial p ort, on-chip oscillator, a nd clock cir -

cuitry. In addition, the AT89C52 is designed with static logic

for operation down to zero frequency and supports two

software selectable power saving modes. The Idle Mode

stops the CPU while allowing the RA M, timer/counters,

serial port, and interrupt system to continue fun ctioning .

The Power Down Mode saves the RAM contents but

freezes th e o sc illa tor , d isabl in g a ll ot her chi p fu nc tio ns un til

the next hardware reset.

Pin Description

VCC

Supply voltage.

GND

Ground.

Port 0

Port 0 is an 8-bi t open drain bidirectional I/O port. As an

output port, each pin can sink eight TTL inputs. When 1s

are written to port 0 pins, the pins can be used as high-

impedance inputs.

Port 0 can also be configured to be the multiplexed l ow-

order address/data bus during accesses to external pr o-

gram and data memory. In this mode, P0 has internal pul-

lups.

Port 0 a lso rec eives th e code bytes d uring Fla sh prog ram-

ming and outputs the code bytes during program veri fica-

tion. E xternal pullu ps are re quired during program verifi ca-

tion.

Port 1

Port 1 is a n 8- bit bi dire ction al I/O por t with inter nal pullu ps.

The Port 1 output buffers can sink/source four TTL inputs.

When 1s are writte n to Port 1 pi ns, they ar e pulled hi gh by

the internal pullups and can be us ed as inputs. As i nputs,

Port 1 pins that are externally being pulled low will source

current (IIL) because of the internal pullups.

In addition, P1.0 and P1.1 can be configured to be the

timer/counter 2 external count input (P1.0/T2) and the

timer/counter 2 trigger input (P1.1/T2EX), respectivel y, as

shown in the following table.

Port 1 also receives the low-order address bytes during

Flash programming and verification.

Port 2

Port 2 is an 8-bit bi directiona l I/O port with interna l pullups.

The Port 2 output buffers can sink/source four TTL inputs.

When 1s a re writte n to Po rt 2 pi ns, th ey a re pulle d hi gh b y

the internal pullups and can be used as inputs. As inputs,

Port 2 pins that are externally being pulled low will source

current (IIL) be cause of the internal pullups.

Port 2 emits the high-order address byte during fetches

from external program memory and during accesses to

external da ta m emory that u se 16 -bit address es ( MO VX @

DPTR). In this application, Port 2 uses strong internal pul-

lups when emitting 1s. During accesses to external data

memory that use 8-bit addresses (MOVX @ RI), Port 2

emits the contents of the P2 Special Function Register.

Port 2 also receives the high-order address bits and some

control signals during Flash programming and verification.

Port 3

Port 3 is an 8-bit bi directiona l I/O port with interna l pullups.

The Port 3 output buffers can sink/source four TTL inputs.

When 1s a re writte n to Po rt 3 pi ns, th ey a re pulle d hi gh b y

the internal pullups and can be used as inputs. As inputs,

Port 3 pins that are externally being pulled low will source

current (IIL) because of the pullups.

Port 3 also s erves the funct ions of var ious s peci al featu res

of the AT89C51, as shown in the following table.

Port 3 also receives some control signals for Flash pro-

gramming and verification.

RST

Reset input. A high on this pin for two machine cycles while

the oscillator is running resets the device.

ALE/PROG

Address Latch Enabl e is an output pulse for latching the

low byte of the address during accesses to external mem-

ory . Thi s pi n is also t h e pr og ra m pu l se in p ut (PROG) during

Flash programming.

In normal operation, ALE is emitted at a constant rate of 1/6

the oscillator frequency and may be used for external tim-

ing or clocking purposes. Note, however, that one ALE

Port Pin Alternate Functions

P1.0 T2 (external count input to Timer/Counter 2),

clock-out

P1.1 T2EX (Timer/Counter 2 capture/reload trigger

and direction control)

Port Pin Alternate Functions

P3.0 RXD (serial input port)

P3.1 TXD (serial output port)

P3.2 INT0 (external interrupt 0)

P3.3 INT1 (external interrupt 1)

P3.4 T0 (timer 0 external input)

P3.5 T1 (timer 1 external input)

P3.6 WR (external data memory write strobe)

P3.7 RD (external data memory read strobe)

AT89C52

4-64

pulse i s sk ipped during e ac h ac c ess t o ex te rn al data me m-

ory.

If desired, ALE operation can be disabled by setting bit 0 of

SFR location 8EH. With the bit set, ALE is active only dur-

ing a MOVX or MOVC instruction. Otherwise, the pin is

weakly pulled high. Setting the ALE-disable bit has no

effect if the microcontroller is in external execution mode.

PSEN

Program Store Enable is the read strobe to external pro-

gram memory.

When the AT89C52 is executing code from external pro-

gram memory, PSEN is activated twice each machine

cycle, except that two PSEN activations are skipped during

each access to external data memory.

EA/VPP

External Access Enable. EA must be str apped to GND in

order to enable the device to fetch code from external pro-

gram memory locations starting at 0000H up to FFFFH.

Note, however, that if lock bit 1 is programmed, EA will be

internally latched on reset.

EA should be strapped to VCC for internal program execu-

tions.

This pin also receives the 12-volt programming enable volt-

age (VPP) during Flash programming when 12-volt pro-

gramming is selected.

XTAL1

Input to the inverting os cillator ampli fier and inp ut to the

internal clock operating circuit.

XTAL2

Output from the inverting oscillator amplifier.

Table 1. AT89C52 SFR Map and Reset Values

0F8H 0FFH

0F0H B

00000000 0F7H

0E8H 0EFH

0E0H ACC

00000000 0E7H

0D8H 0DFH

0D0H PSW

00000000 0D7H

0C8H T2CON

00000000 T2MOD

XXXXXX00 RCAP2L

00000000 RCAP2H

00000000 TL2

00000000 TH2

00000000 0CFH

0C0H 0C7H

0B8H IP

XX000000 0BFH

0B0H P3

11111111 0B7H

0A8H IE

0X000000 0AFH

0A0H P2

11111111 0A7H

98H SCON

00000000 SBUF

XXXXXXXX 9FH

90H P1

11111111 97H

88H TCON

00000000 TMOD

00000000 TL0

00000000 TL1

00000000 TH0

00000000 TH1

00000000 8FH

80H P0

11111111 SP

00000111 DPL

00000000 DPH

00000000 PCON

0XXX0000 87H

AT89C52

4-65

Special Function Registers

A map of the on-chip memory area called the Special Func-

tion Register (SFR) space is shown in Table 1.

Note that not all of the addresses are occupied, and unoc-

cupied addresses may not be implemented on the chip.

Read accesses to these addresses will in general return

random data, and write accesses will have an indetermi-

nate effect.

User software should not write 1s to these unlisted loca-

tions, since they may be used in future products to invoke

new featu res. In th at case, the r eset or inac tive valu es of

the new bits will always be 0.

Timer 2 Registers: Control and status bits are contained

in registers T2CON (shown in Table 2) and T2MOD (shown

in Table 4) for Timer 2. The register pair (RCAP2H,

RCAP2L) are the Captur e/Reload regi sters for Tim er 2 in

16-bit capture mode or 16-bit auto-reload mode.

Interrupt Registers: The individual interrupt enable bits

are in the IE register. Two priorities can be set for each of

the six interrupt sources in the IP register.

Table 2. T2CON—Timer/Counter 2 Control Register

Data Memory

The AT89C52 implements 256 bytes of on-chip RAM. The

upper 128 bytes occupy a pa rallel address space to the

Special Function Registers. That means the upper 128

bytes have the same addresses as the SFR space but are

physically separate from SFR space.

When an instruction accesses an internal location above

address 7FH, the address mode used in the instruction

specifies whether the CPU accesses the upper 128 bytes

of RAM or the SFR space. Instructions that use direct

addressing access SFR space.

For example, the following direct addressing instruction

accesses the SFR at location 0A0H (which is P2).

MOV 0A0H, #data

Instructions that use indirect addressing access the upper

128 bytes of RAM. For example, the following indirect

address in g i nst ru cti on , wher e R0 conta ins 0A 0H, a cc ess es

the data byte at address 0A0H, rather than P2 (whose

address is 0A0H).

MOV @R0, #data

Note that stack operations are examples of indirect

address ing, so the uppe r 128 bytes of data RAM are av ail-

able as stack space.

T2CO N Addr ess = 0C8H Reset Value = 0000 0000B

Bit Addressable

Bit TF2 EXF2 RCLK TCLK EXEN2 TR2 C/T2 CP/RL2

76543210

Symbol Function

TF2 Timer 2 overflow flag set by a Timer 2 overflow and must be cleared by software. TF2 will not be set when either

RCLK = 1 or TCLK = 1.

EXF2 Timer 2 external flag set when either a capture or reload is caused by a negative transition on T2EX and EXEN2 =

1. When Timer 2 interrupt is enabled, EXF2 = 1 will cause the CPU to vector to the Timer 2 interrupt routine. EXF2

must be cleared by software. EXF2 does not cause an interrupt in up/down counter mode (DCEN = 1).

RCLK Receive clock enable. When set, causes the serial port to use Timer 2 overflow pulses for its receive clock in serial

port Modes 1 and 3. RCLK = 0 causes Timer 1 overflow to be used for the receive clock.

TCLK Trans mit c loc k en ab le . When s et, cau ses the serial port to use Timer 2 o v erf lo w puls es f o r its tr ansm it clock in serial

port Modes 1 and 3. TCLK = 0 causes Timer 1 overflows to be used for the transmit clock.

EXEN2 Timer 2 external enable. When set, allows a capture or reload to occur as a result of a negative transition on T2EX

if Timer 2 is not being used to clock the serial port. EXEN2 = 0 causes Timer 2 to ignore events at T2EX.

TR2 Start/Stop control for Timer 2. TR2 = 1 starts the timer.

C/T2 Timer or counter select for Timer 2. C/T2 = 0 for timer function. C/T2 = 1 for external event counter (falling edge

triggered).

CP/RL2 Capture/Reload select. CP/RL2 = 1 caus es captures to occur on negativ e tr ansition s at T2EX if EXEN2 = 1. CP/RL2

= 0 causes automatic reloads to occur when Timer 2 overflows or negative transitions occur at T2EX when EXEN2

= 1. When either RCLK or TCLK = 1, this bit is ignored and the timer is forced to auto-reload on Timer 2 overflow.

AT89C52

4-66

Timer 0 and 1

Timer 0 and Timer 1 in the AT89C52 operate the same way

as Timer 0 and Timer 1 i n the AT89C51.

Timer 2

Timer 2 is a 16-bit Timer/Counter that can operate as either

a timer or an event counter. The type of operation is

selected by bit C/T2 in the SF R T 2 CO N ( sh ow n i n Ta bl e 2) .

Timer 2 has three operating modes: capture, auto-reload

(up or down counting), and baud rate generator. The

modes are selected by bits in T2CON, as shown in Table 3.

Timer 2 c onsis ts of tw o 8- bit r egi st er s, TH2 and TL2. I n the

Timer function, the TL2 register is incremented every

machine cycle. Since a machine cycle consists of 12 oscil-

lator periods, the count rate is 1/12 of the oscillator fre-

quency.

Table 3. Timer 2 Operating Modes

In the Counter function, the register is incremented in

response to a 1-to-0 transition at its corresponding external

input p in, T2 . In this func tion, the extern al inpu t is sa mpled

during S5P2 of every machine cy cle. When the samp les

show a high in one cycle and a low in the next cycle, the

count is incremented. The new count value appears in the

the transition was detected. Since two machine cycles (24

oscill ato r perio ds ) ar e requi re d t o r ec ogn iz e a 1 -to -0 tran si -

tion, the maximum count rate is 1/24 of the oscillator fre-

quency. To ensure that a given level is sampled at least

once before it changes, the level should be held for at least

one full machine cycle.

Capture Mode

In the capture mode, two options are selected by bit

EXEN2 in T2CON. If EXEN2 = 0, Timer 2 is a 16-bit timer

or counter which upon overflow sets bit TF2 in T2CON.

This bit can then be used to generate an interrupt. If

EXEN2 = 1, Tim er 2 p erf orms t he sa me op er ati on, bu t a 1 -

to-0 transition at external input T2EX also causes the cur-

rent value in TH2 and TL2 to be captured into RCAP2H and

RCAP2 L, resp ectivel y. In addit ion, the t ransiti on at T2E X

causes bit EXF2 in T2CON to be set. The EXF2 bit, like

TF2, can generate an interrupt. The capture mode is illus-

trated in Figure 1.

Aut o-Relo ad (Up or Down Counter)

Timer 2 can be programmed to count up or down when

configured in its 16-bit auto-reload mode. This featur e is

invoked by the DCEN (Down Counter Enable) bit located in

the SFR T2MOD (see Table 4). Upon reset, the DCEN bit

is set to 0 so that timer 2 will default to count u p. When

DCEN is se t, Time r 2 c an coun t up o r dow n, depe nding on

the value of the T2EX pin.

RCLK +TCLK CP/RL2 TR2 MODE

0 0 1 16-Bit Auto-Reload

0 1 1 16-Bit Capture

1 X 1 Baud Rate Generator

X X 0 (Off)

Figure 1. Timer in Capture Mode

OSC

EXF2

T2EX PIN

T2 PIN

TR2

EXEN2

C/T2 = 0

C/T2 = 1 CONTROL

CAPTURE

OVERFLOW

CONTROL

TRANSITION

DETECTOR TIMER 2

INTERRUPT

÷12

RCAP2LRCAP2H

TH2 TL2 TF2

AT89C52

4-67

Figure 2 shows Timer 2 automatically counting up when

DCEN = 0. In this mode, two options are selected by bit

EXEN2 in T2CON. If EXEN2 = 0, Timer 2 counts up to

0FFFFH and then sets the TF2 bit upon overflow. The over-

flow al so c auses the timer regi ste r s to be re loa ded with the

16-bit val ue in RCAP2H and RCA P2 L. The v alu es in Tim er

in Captur e Mo deRCAP 2H and RCAP2 L are prese t by soft-

ware. I f EX EN2 = 1, a 16 -bit reloa d ca n be tri gger ed ei ther

by an overflow or by a 1-to-0 transition at external input

T2EX. This transition also sets the EXF2 bit. Both the TF2

and EXF2 bits can generate an interrupt if enabled.

Setting th e DCE N bi t ena bles Ti me r 2 to c oun t up o r down ,

as shown in Figure 3. In this mode, the T2EX pin controls

the direction of the count. A logic 1 at T2EX makes Timer 2

count up. The timer will overflow at 0FFFFH and set the

TF2 bit. This overflow also causes the 16-bit value in

RCAP2H and RCAP2L to be reloaded into the timer regis-

ters, TH2 and TL2, respectively.

A logic 0 at T2EX makes Timer 2 count down. The timer

underflows when TH2 and TL2 equal the value s stored in

RCAP2H and RCAP2L. The underflow sets the TF2 bit and

causes 0FFFFH to be reloaded into the timer registers.

The EXF2 bit toggles whenever Timer 2 overflows or

underflows and can be used as a 17th bit of resolution. In

this operating mode, EXF2 does not flag an interrupt.

Figure 2. Timer 2 Auto Reload Mode (DCEN = 0)

Table 4. T2MOD—Timer 2 Mode Control Register

OSC

EXF2

TF2

T2EX PIN

T2 PIN

TR2

EXEN2

C/T2 = 0

C/T2 = 1

CONTROL

RELOAD

OVERFLOW

CONTROL

TRANSITION

DETECTOR

TIMER 2

INTERRUPT

÷12

RCAP2LRCAP2H

TH2 TL2

T2MOD Address = 0C9H Reset Value = XXXX XX00B

Not Bit Addressable

——————T2OEDCEN

Bit76543210

Symbol Function

— Not implemented, reserved for future

T2OE Timer 2 Output Enable bit.

DCEN When set, this bit allows Timer 2 to be configured as an up/down counter.

AT89C52

4-68

Figure 3. Timer 2 Auto Reload Mode (DCEN = 1)

Figure 4. Timer 2 in Baud Rate Generator Mode

OSC

EXF2

TF2

T2EX PIN

COUNT

DIRECTION

1=UP

0=DOWN

T2 PIN

TR2

CONTROL

OVERFLOW

(DOWN COUNTING RELOAD VALUE)

(UP COUNTING RELOAD VALUE)

TOGGLE

TIMER 2

INTERRUPT

RCAP2LRCAP2H

0FFH0FFH

TH2 TL2

C/T2 = 0

C/T2 = 1

OSC

SMOD1

RCLK

TCLK

CLOCK

T2EX PIN

T2 PIN

TR2

CONTROL

"1"

"0"

TIMER 1 OVERFLOW

NOTE: OSC. FREQ. IS DIVIDED BY 2, NOT 12

TIMER 2

INTERRUPT

RCAP2LRCAP2H

TH2 TL2

C/T2 = 0

C/T2 = 1

EXF2

CONTROL

TRANSITION

DETECTOR

EXEN2

AT89C52

4-69

Baud Rate Generator

Timer 2 is selected as the baud rate generator by setting

TCLK and/or RCLK in T2CON (Table 2). Note that the baud

rates for transmit and receive can be different if Timer 2 is

used fo r the rece iver o r tran smit ter a nd Tim er 1 is us ed f or

the other function. Setting RCLK and/or TCLK puts Timer 2

into its baud rate generator mode, as shown in Figure 4.

The baud rate gener ator m ode i s sim ilar to the auto- reload

mode, in that a rollover in TH2 causes the Timer 2 registers

to be reloaded with the 16-bit value in registers RCAP2H

and RCAP2L, which are preset by software.

The baud r ates in Mod es 1 a nd 3 are det ermined by Tim er

2’s overflow rate according to the following equation.

The Timer can be configured for either timer or counter

operation. In most applicat ions, it is configured for tim er

operation (CP/T2 = 0). The timer operation i s different for

Timer 2 when it is used as a baud rate generator. Normally,

as a timer, it increments every machine cy cle (at 1/12 the

oscill ator fre quency) . As a ba ud rate gen erator, h owever , it

increments every state time (at 1/2 the oscillator fre-

quency). The baud rate formula is given below.

where (RCAP2H, RCAP2L) is the content of RCAP2H and

RCAP2L taken as a 16-bit unsigned integer.

Timer 2 as a baud rate generator is shown in Figure 4. This

figure is valid only if RCLK or TCLK = 1 in T2CON. Note

that a rollover in TH2 does not set TF2 and will not gener-

ate an interrupt. Note too, that if EXEN2 is set, a 1-to-0

transitio n in T2EX will set EXF2 but will not cause a reload

from (RCAP2 H, RCAP2 L) to (TH2, TL2 ). Thus when Timer

2 is in us e as a baud r ate gen erator, T2E X can be used as

an extra ext ernal interrupt.

Note that when Timer 2 is running ( TR2 = 1) as a timer in

the baud rate generator mode, TH2 or TL2 should not be

read from or written to. Under these conditions, the Timer is

incremented every state time, a nd the results of a read or

write may not be accurate. The RCAP2 registers may be

read but should not be written to, because a write might

overlap a reload and cause write and/or reload errors. The

timer should be turned off (clear TR2) before accessing the

Timer 2 or RCAP2 registers.

Figure 5. Timer 2 in Clock-Out Mode

Modes 1 and 3 Baud Rates Timer 2 Overflow Rate

------------------------------------------------------------=

Modes 1 and 3

Baud Rate

--------------------------------------- Oscillator Frequency

32 65536 RCAP2H RCAP2L

(,)–[]×

---------------------------------------------------------------------------------------------=

OSC

EXF2

P1.0

(T2)

P1.1

(T2EX)

TR2

EXEN2

C/T2 BIT

TRANSITION

DETECTOR

TIMER 2

INTERRUPT

T2OE (T2MOD.1)

÷2 TL2

(8-BITS)

RCAP2L RCAP2H

TH2

(8-BITS)

÷2

AT89C52

4-70

Programmable Clock Out

A 50% duty cycle clock can be programmed to come out on

P1.0, as shown in Figure 5. This pin, besides being a regu-

lar I/O pin, has two alternate functions. It can be pro-

grammed to i np ut the e xte rnal c lo ck for Time r/ Coun ter 2 or

to output a 50% duty cycle clock ranging from 61 Hz to 4

MHz at a 16

MHz operating frequency.

To configure the Timer/Counter 2 as a clock generator, bit

C/T2 (T2CON.1) must be cleared and bit T2OE (T2MOD.1)

must be set. Bit TR2 (T2CON.2) starts and stops the timer.

The clock-out frequency depends on the oscillator fre-

quenc y and the rel oad valu e of Timer 2 capt ure regis ters

(RCAP2H, RCAP2L), as shown in the following equation.

In the clock-out mode, Timer 2 roll-overs will not generate

an interrupt. This behavior is similar to when Timer 2 is

used as a baud-rate generator. It is possible to use Timer 2

as a baud -rate generator and a clock g enerator simulta-

neously. Note, however, that the baud-rate and clock-out

frequencies cannot be determined independently from one

another since they both use RCAP2H and RCAP2L.

UART

The UART in the AT89C52 operates the same way as the

UART in the AT89C51.

Interrupts

The AT89C52 has a total of six interrupt vectors: two exter-

nal interrupts (INT0 and INT1), three tim er interru pts (Tim-

ers 0, 1, and 2), and the serial por t interrupt . These in ter-

rupts are all shown in Figure 6.

Each of these interrupt sources can be individually enabled

or disabled b y setting or clearing a bit in Special Function

disables all interrupts at once.

Note that Table 5 shows that bit position IE.6 is unimple-

mented. In the AT89C51, bit position IE.5 is also unimple-

mented. User software should not write 1s to these bit posi-

tions, since they may be used in future AT89 products.

Timer 2 in terr upt is gen erated by the log ic al OR o f bi ts TF2

and EXF2 in register T2CON. Neither of these flags is

cleared by hardware whe n the ser vice routine i s vectored

to. In fact, the service routine may have to determine

whether it was TF2 or EXF2 that generated the interrupt,

and that bit will have to be cleared in software.

The Timer 0 and Timer 1 flags, TF0 and TF1, are set at

S5P2 of the cycle in whi ch the timers overflow. The values

are then polled by the circuitry in the next cycle. However,

the Timer 2 flag, TF2, is set at S2P2 and is polled in the

same cycle in which the timer overflows.

Table 5. Interrupt Enable (IE) Register

Figure 6. Interrupt Sources

Clock-Out Frequency Oscillator Fequen cy

4 65536 RCAP2H RCAP2L

(,)–[]×

------------------------------------------------------------------------------------------=

(MSB) (LSB)

EA — ET2 ES ET1 EX1 ET0 EX0

Enable Bit = 1 enables the interrupt.

Enable Bit = 0 disables the interrupt.

Symbol Position Function

EA IE.7 Disables all interrupts. If EA = 0,

no interrupt is acknowledged. If

EA = 1, each interrupt source is

individu all y ena bled or disabl ed

by setting or clearing its enable

bit.

— IE.6 Reserved.

ET2 IE.5 Timer 2 interrupt enable bit.

ES IE.4 Serial Port interrupt enable bit.

ET1 IE.3 Timer 1 interrupt enable bit.

EX1 IE.2 External interrupt 1 enable bit.

ET0 IE.1 Timer 0 interrupt enable bit.

EX0 IE.0 External interrupt 0 enable bit.

User software should never write 1s to unimplemented bits,

because they may be used in future AT89 products.

IE1

IE0

TF1

TF0

INT1

INT0

TF2

EXF2

AT89C52

4-71

Oscillator Characteristics

XTAL1 and XTA L2 are the input and output, respe ctively,

of an invertin g amplifi er that can be co nfigured for use as

an on-chip oscillator, as shown in Figure 7. Either a quartz

crystal or ceramic resonator may be used. To drive the

device from an external clock source, XTAL2 should be left

unconnected while XTAL1 is driven, as shown in Figure 8.

There are no requirements on the duty cycle of the external

clock signal, since the input to the internal clocking circuitry

is through a divide-by-two flip-flop, but minimum and maxi-

mum voltage high and low time specifications must be

observed.

Idle Mode

In idle mode, the CPU puts itself to sl eep while all the on-

chip peripherals remain active. The mode is invoked by

software. The content of the on-chip RAM and all the spe-

cial functions registers remain unchanged during this

mode. The i dle mode can be terminated by any en abled

interrupt or by a hardware reset.

Note that when idle mode is terminated by a hardware

reset, the device normally resumes program execution

from where it left off, up to two mac hine cycles before the

internal reset algorithm takes control. On-chip hardware

inhibits access to internal RAM in this event, but access to

the port pins is not inhibited. To eliminate the possibility of

an unexpected write to a port pin when idle mode is termi-

nated by a reset, the instruction following the one that

invo ke s idl e m ode s hou ld not write to a p or t p in or to exter-

nal memory.

Power Down Mode

In the power down mod e, the oscillato r is stopped, and the

inst ruction that in vokes power down is th e last instru ction

executed. The on-chip RAM and Special Function Regis-

ters retai n their v alues until the p ower d own mode is termi -

nated. Th e only exi t from pow er down is a hard ware reset .

Reset redefines the SFRs but does not cha nge the on-chip

RAM. The reset should not be activated before VCC is

restored to its normal operating level and must be held

active long enough to allow the oscillator to restart and sta-

bilize.

Figure 7. Oscillator Connections

Note: C1, C2 = 30 pF ± 10 pF for Crystals

= 40 pF ± 10 pF for Ceramic Resonators

Figure 8. External Clock Drive Configuration

Status of External Pins During Idle and Power Down Modes

C2 XTAL2

GND

XTAL1

XTAL2

XTAL1

GND

EXTERNAL

OSCILLATOR

SIGNAL

Mode Pro gram Memory ALE PSEN PORT0 PORT1 PORT2 PORT3

Idle Internal 1 1 Data Data Data Data

Idle External 1 1 Float Data Address Data

Power Down Internal 0 0 Data Data Data Data

Power DownExternal 00FloatDataDataData

AT89C52

4-72

Program Memory Lock Bits

The AT89C52 has three lock bits that can be left unpro-

grammed (U) or can be programmed (P) to obtain the addi-

tional features listed in the following table.

Lock Bit Protection Modes

When lock bit 1 is programmed, the logic level at the EA pin

is sampled and la tched during rese t. If the devic e is pow-

ered up without a reset, the l atch initial izes to a r andom

value and holds that value until reset is activated. The

latched value of EA must agree wi th the cur rent lo gic level

at that pin in order for the device to function properly.

Programming the Flash

The AT89C52 is normally shipped with the on-chip Flash

memor y array in th e erased state (th at is, con tents = FF H)

and ready to be program med. The programming interface

accepts either a high-voltage (12-volt) or a low-voltage

(VCC) program enable signal. The low voltage program-

ming mode provides a convenient way to program the

AT89C52 inside the user’s system, while the high-voltage

programm ing mode is c ompatible with con ventional third-

party Flash or EPROM programmers.

The AT89C52 is shipped with either the high-voltage or

low-voltage programming mode enabled. The respective

top-sid e marking and devic e signature co des are listed in

the following table.

The AT89C 52 cod e memo ry array is pro grammed byte-by -

byte in either programming mode.

To program any non-

blank byt e in th e on- chip Flas h Mem ory, the entir e mem ory

must be erased using the Chip Erase Mode.

Programming Algorithm: Before programming the

AT89 C52, the addre ss, data and con trol si gnals s hould be

set up according to the Flash programming mode table and

Figures 9 and 10. To program the AT89 C52, take the fol -

lowing steps.

1. Input the desired memory location on the address

lines.

2. Input the appropriate data byte on the data lines.

3. Activate the correct combination of control signals.

4. Raise EA/VPP to 12V for the high-volta ge programming

mode.

5. Pulse ALE/PROG once to program a byte in the Flash

array or the lock bits. The byte-write cycle is self-timed

and typical ly takes no more tha n 1.5 ms. Repeat ste ps

1 through 5, changing the address and data for the

entire array or until the end of the object file is reached.

Data Polling: The AT89C52 features Data Polling to indi-

cate the end of a write cycle. During a write cycle, an

attempted read of the last byte written will result in the com-

plement of the wr itten data on PO .7. Once the write cyc le

has been compl eted, true data is val id on all outputs, and

the next c ycle may begin . Data Po lling ma y begin an y time

after a write cycle has been initiated.

Ready/Busy: The progress of byte programming can also

be monitor ed by the RDY/B SY ou tput si gna l. P 3. 4 is p ull ed

low after ALE goes high during programming to indicate

BUSY. P3.4 is pulled high again when programming is

done to indicate READY.

Program Verify: If lock bits LB1 and LB2 have not been

programmed, the programmed code data can be read back

via the addr ess and data li nes for verificati on. The loc k bits

cannot b e verified dire ctly. Verification of the lock bi ts is

achieved by observing that their features are enabled.

Program Lock Bits

LB1 LB2 LB3 Protection Type

1 U U U No program lock features.

2 P U U MOVC instructions executed

from external program

memory are dis abled from

fetching code bytes from

internal memory, EA is

sample d and latche d on reset,

and further programmi ng of

the Flash memory is disabled.

3 P P U Same as mode 2, but ver i fy is

also disabled.

4 P P P Same as mode 3, but external

execution is also d isabled.

VPP = 12V VPP = 5V

Top-Side Mark AT89C52

xxxx

yyww

AT89C52

xxxx-5

yyww

Signature (030H)=1EH

(031H)=52H

(032H)=FFH

(030H)=1EH

(031H)=52H

(032H)=05H

AT89C52

4-73

Chip Erase: The entire Flash array is erased electrically

by using the proper com bination of contr ol signals and by

holding ALE/PROG low for 10 ms. The code array is written

with all 1s. The chip erase operation must be executed

before the code memory can be reprogrammed.

Reading the Signature Bytes: The si gnature bytes a re

read by the same procedure as a normal verification of

locations 030H, 031H, and 032H, except that P3.6 and

P3.7 must be pulled to a logic low. The values returned are

as follows.

(030H) = 1EH indicates manufactured by Atmel

(031H) = 52H indicates 89C52

(032H) = FFH indicates 12V programming

(032H) = 05H indic at es 5V progr am mi ng

Pr ogramming Interface

Every code byte in the Flash array can be written, and the

entire array can be erased, by using the appropriate combi-

nation of control signal s. The write operation cycle i s self-

timed and once initiated, will automatically time itself to

completion.

All maj or prog ramming ve ndors of fer worl dwide s upport fo r

the Atmel microcontroller series. Please contact your local

programming vendor for the appropriate software revision.

Flash Programming Modes

Note: 1. Chip Erase requires a 10-ms PROG pulse.

Mode RST PSEN ALE/PROG EA/VPP P2.6 P2.7 P3.6 P3.7

Write Code Data H L H/12V L H H H

Read Code Data H L H H L L H H

Write Lock Bit - 1 H L H/12V H H H H

Bit - 2 H L H/12V H H L L

Bit - 3 H L H/12V H L H L

Chip Erase H L H/12V H L L L

Read Signature Byte H L H H L L L L

(1)

AT89C52

4-74

Figure 10. Verifying the Flash Memory

P2.6

P3.6

P2.0 - P2.4

A0 - A7

ADDR.

OOOOH/1FFFH

SEE FLASH

PROGRAMMING

MODES TABLE

3-24 MHz

A8 - A12 P0

+5V

P2.7

PGM DATA

(USE 10K

PULLUPS)

VIH

ALE

P3.7

XTAL2 EA

RST

PSEN

XTAL1

GND

VCC

AT89C52

Figure 9. Programming the Flash Memory

P2.6

P3.6

P2.0 - P2.4

A0 - A7

ADDR.

OOOOH/1FFFH

SEE FLASH

PROGRAMMING

MODES TABLE

3-24 MHz

A8 - A12 P0

+5V

P2.7

PGM

DATA

PROG

V/V

IH PP

VIH

ALE

P3.7

XTAL2 EA

RST

PSEN

XTAL1

GND

VCC

AT89C52

Flash Programming and Verification Characteristics

TA = 0°C to 70°C, VCC = 5.0 ± 10%

Note: 1. Only used in 12-volt programming mode.

Symbol Parameter Min Max Units

VPP(1) Programming E nable Voltage 11.5 12.5 V

IPP(1) Programming Enable Current 1.0 mA

1/tCLCL Oscillator Frequency 3 24 MHz

tAVGL Address Setup to PROG Low 48tCLCL

tGHAX Address Hold After PROG 48tCLCL

tDVGL Data Setup to PROG Low 48tCLCL

tGHDX Data Hold After PROG 48tCLCL

tEHSH P2.7 (ENABLE) High to VPP 48tCLCL

tSHGL VPP Setup to PROG Low 10 µs

tGHSL(1) VPP Hold After PROG 10 µs

tGLGH PROG Width 1 110 µs

tAVQV Address to Data Valid 48tCLCL

tELQV ENABLE Low to Data Valid 48tCLCL

tEHQZ Data Float After ENABLE 0 48tCLCL

tGHBL PROG High to BUSY Low 1.0 µs

tWC Byte Write Cycle Time 2.0 ms

AT89C52

4-75

Flash Programming and Verification Waveform s - Low Voltage Mode (V PP=5V)

tGLGH

tAVGL

tSHGL

tDVGL tGHAX

tAVQV

tGHDX

tEHSH tELQV

tWC

BUSY READY

tGHBL

tEHQZ

P1.0 - P1.7

P2.0 - P2.4

ALE/PROG

PORT 0

LOGIC 1

LOGIC 0

EA/V

P2.7

(ENABLE)

P3.4

(RDY/BSY)

PROGRAMMING

ADDRESS VERIFICATION

ADDRESS

DATA IN DATA OUT

Flash Programming and Verification Waveform s - High Voltage Mode (VPP=12V)

tGLGH tGHSL

tAVGL

tSHGL

tDVGL tGHAX

tAVQV

tGHDX

tEHSH tELQV

tWC

BUSY READY

tGHBL

tEHQZ

P1.0 - P1.7

P2.0 - P2.4

ALE/PROG

PORT 0

LOGIC 1

LOGIC 0

EA/V

P2.7

(ENABLE)

P3.4

(RDY/BSY)

PROGRAMMING

ADDRESS VERIFICATION

ADDRESS

DATA IN DATA OUT

(2)

AT89C52

4-76

Absolute Maximum Ratings*

DC Characteristics

The values shown in this table are valid for TA = -40°C to 85°C and VCC = 5.0V ± 20%, unless otherwise noted.

Notes: 1. Under steady state (non-transient) conditions, IOL must be externally limi ted as follows:

Maximum IOL per port pin: 10 mA

Maximum IOL per 8-bit port:

Port 0: 26 mA Ports 1, 2, 3: 15 mA

Maximum total IOL for all output pins: 71 mA

If IOL exceeds the test condition, VOL may exceed the related specification. Pins are not guaranteed to sink current greater

than the listed test conditions.

2. Minimum VCC for Power Down is 2V.

Operating Temperature.................................. -55°C to +125°C *NOTICE: Stresses beyond those listed under “Absolute

Maximum Ratings” may cause permanent dam-

age to th e de vice . This is a stress rating o nly and

funct ional ope ration of the de vice at these or an y

other conditions beyond those indicated in the

operational sections of this specification is not

implied. Exposure to absolute maximum rating

conditions for extended periods may affect

device reliability.

Storage Temperature..................................... -65°C to +150°C

Voltage on Any Pin

with Respect to Ground.....................................-1.0V to +7.0V

Maximum Operating Voltage............................................. 6.6V

DC Output Current...................... ...... ................. ..... .... 15.0 mA

Symbol Parameter Condition Min Max Units

VIL Input Low Voltage (Except EA)-0.50.2 V

CC-0.1 V

VIL1 Input Low Voltage (EA)-0.50.2 V

CC-0.3 V

VIH Input High Voltage (Except XTAL1, RST) 0.2 VCC+0.9 VCC+0.5 V

VIH1 Input High Voltage (XTAL1, RST) 0.7 VCC VCC+0.5 V

VOL Output Low Voltage(1) (P orts 1,2,3) IOL = 1.6 mA 0.45 V

VOL1 Output Low Voltage(1)

(Port 0, ALE, PSEN) IOL = 3.2 mA 0.45 V

VOH Output High Voltage

(Ports 1,2,3, ALE, PSEN)IOH = -60 µA, VCC = 5V ± 10% 2.4 V

IOH = -25 µA 0.75 VCC V

IOH = -10 µA0.9 V

CC V

VOH1 Output High Voltage

(Port 0 in External Bus Mode) IOH = -800 µA, VCC = 5V ± 10% 2.4 V

IOH = -300 µA 0.75 VCC V

IOH = -80 µA0.9 V

CC V

IIL Logical 0 Input Current (Ports 1,2,3) VIN = 0.45V -50 µA

ITL Logical 1 to 0 Transition Current

(Ports 1,2,3) VIN = 2V, VCC = 5V ± 10% -650 µA

ILI Input Leakage Current (Port 0, EA) 0.45 < VIN < VCC ±10 µA

RRST Reset Pulldown Resistor 50 300 KΩ

CIO Pin Capacitance Test Freq. = 1 MHz, TA = 25°C 10 pF

ICC Power Supply Current Active Mode, 12 MHz 25 mA

Idle Mode, 12 MHz 6.5 mA

Power Down Mode(1) VCC = 6V 100 µA

VCC = 3V 40 µA

AT89C52

4-77

AC Characterist ics

Under operating conditions, load capacitance for Port 0, ALE/PROG, and PSEN = 100 pF; load capacitance for all other

outputs = 80 pF.

External Program and Data Memory Characteristics

Symbol Parameter 12 MHz Oscillator Variable Oscillator Units

Min Max Min Max

1/tCLCL Oscillator Frequency 0 24 MHz

tLHLL ALE Pulse Width 127 2tCLCL-40 ns

tAVLL Address Valid to ALE Low 43 tCLCL-13 ns

tLLAX Address Hold After ALE Low 48 tCLCL-20 ns

tLLIV ALE Low to Valid Instruction In 233 4tCLCL-65 ns

tLLPL ALE Low to PSEN Low 43 tCLCL-13 ns

tPLPH PSEN Pulse Width 205 3tCLCL-20 ns

tPLIV PSEN Low to Valid Instruction In 145 3tCLCL-45 ns

tPXIX Input Instruction Hold After PSEN 00ns

PXIZ Input Instruction Float After PSEN 59 tCLCL-10 ns

tPXAV PSEN to Address Valid 75 tCLCL-8 ns

tAVIV Address to Valid Instruction In 312 5tCLCL-55 ns

tPLAZ PSEN Low to Address Float 10 10 ns

tRLRH RD Pulse Width 400 6tCLCL-100 ns

tWLWH WR Pulse Width 400 6tCLCL-100 ns

tRLDV RD Low to Valid Data In 252 5tCLCL-90 ns

tRHDX Data Hold After RD 00ns

RHDZ Data Float After RD 97 2tCLCL-28 ns

tLLDV ALE Low to Valid Data In 517 8tCLCL-150 ns

tAVDV Address to Valid Data In 585 9tCLCL-165 ns

tLLWL ALE Low to RD or WR Low 200 300 3tCLCL-50 3tCLCL+50 ns

tAVWL Address to RD or WR Low 203 4tCLCL-75 ns

tQVWX Data Valid to WR Transi tio n 23 tCLCL-20 ns

tQVWH Data Valid to WR High 433 7 tCLCL-120 ns

tWHQX Data Hold After WR 33 tCLCL-20 ns

tRLAZ RD Low to Address Float 0 0 ns

tWHLH RD or WR High to ALE High 43 123 tCLCL-20 tCLCL+25 ns

AT89C52

4-78

External Program Memory Read Cycle

External Data Memory Read Cycle

tLHLL

tLLIV

tPLIV

tLLAX tPXIZ

tPLPH

tPLAZ tPXAV

tAVLL tLLPL

tAVIV

tPXIX

ALE

PSEN

PORT 0

PORT 2

A8 - A15

A0 - A7 A0 - A7

A8 - A15

INSTR IN

tLHLL

tLLDV

tLLWL

tLLAX

tWHLH

tAVLL

tRLRH

tAVDV

tAVWL

tRLAZ tRHDX

tRLDV tRHDZ

A0 - A7 FROM RI OR DPL

ALE

PSEN

PORT 0

PORT 2

P2.0 - P2.7 OR A8 - A15 FROM DPH

A0 - A7 FROM PCL

A8 - A15 FROM PCH

DATA IN INSTR IN

AT89C52

4-79

External Data Memory Write Cycle

External Clock Drive Wave forms

External Clock Drive

Symbol Parameter Min Max Units

1/tCLCL Oscillator Frequency 0 24 MHz

tCLCL Clock Period 41.6 ns

tCHCX High Time 15 ns

tCLCX Low Time 15 ns

tCLCH Rise Time 20 ns

tCHCL Fall Time 20 ns

tLHLL

tLLWL

tLLAX

tWHLH

tAVLL

tWLWH

tAVWL

tQVWX tQVWH tWHQX

A0 - A7 FROM RI OR DPL

ALE

PSEN

PORT 0

PORT 2

P2.0 - P2.7 OR A8 - A15 FROM DPH

A0 - A7 FROM PCL

A8 - A15 FROM PCH

DATA OUT INSTR IN

CHCX

CLCX

CLCL

CHCL

CLCH

V - 0.5V

0.45V 0.2 V - 0.1V

0.7 V

AT89C52

4-80

Serial Por t Tim ing: Shift Register Mode Test Conditions

The values in this table are valid for VCC = 5.0V ± 20% and Load Capacitance = 80 pF.

Shift Register Mode Timing Waveforms

Symbol Parameter 12 MHz Osc Variable Oscillator Units

Min Max Min Max

tXLXL Serial Port Clock Cycle Time 1.0 12tCLCL µs

tQVXH Output Data Setup to Clock Rising Edge 700 10tCLCL-133 ns

tXHQX Output Data Hold After Clock Rising Edge 50 2tCLCL-117 ns

tXHDX Input Data Hold After Clock Rising Edge 0 0 ns

tXHDV Clock Rising Edge to Input Data Valid 700 10tCLCL-133 ns

tXHDV

tQVXH

tXLXL

tXHDX

tXHQX

ALE

INPUT DATA

CLEAR RI

OUTPUT DATA

WRITE TO SBUF

INSTRUCTION

CLOCK

SET TI

SET RI

VALID VALIDVALID VALIDVALID VALIDVALID VALID

Float Waveform s(1)

Note: 1. For timing purposes, a port pin is no longer floating

when a 100 m V ch an ge fro m l oad volta ge o cc urs. A

port pin begins to float wh en a 100 mV cha nge from

the loaded VOH/VOL level occur s.

VLOAD+ 0.1V

Timing Reference

Points

LOAD- 0.1V

LOAD VVOL+ 0.1V

VOL - 0.1V

AC Testing Input/Output Waveforms(1)

Note: 1. AC Inputs during testing are driven at VCC - 0.5V

for a logic 1 and 0.45V for a logic 0. Timing mea-

sureme nts a re made at VIH min. for a logic 1 and VIL

max. for a logic 0.

0.45V

TEST POINTS

V - 0.5V

CC 0.2 V + 0.9V

0.2 V - 0.1V

AT89C52

4-81

Ordering Information

Speed

(MHz) Power

Supply Ordering Code Package Operation Range

12 5V ± 20% AT89C52-12AC

AT89C52-12JC

AT89C52-12PC

AT89C52-12QC

44A

44J

40P6

44Q

Commercial

(0°C to 70°C)

AT89C52-12AI

AT89C52-12JI

AT89C52-12PI

AT89C52-12QI

44A

44J

40P6

44Q

Industrial

(-40°C to 85°C)

AT89C52-12AA

AT89C52-12JA

AT89C52-12PA

AT89C52-12QA

44A

44J

40P6

44Q

Automotive

(-40°C to 105°C)

16 5V ± 20% AT89C52-16AC

AT89C52-16JC

AT89C52-16PC

AT89C52-16QC

44A

44J

40P6

44Q

Commercial

(0°C to 70°C)

AT89C52-16AI

AT89C52-16JI

AT89C52-16PI

AT89C52-16QI

44A

44J

40P6

44Q

Industrial

(-40°C to 85°C)

AT89C52-16AA

AT89C52-16JA

AT89C52-16PA

AT89C52-16QA

44A

44J

40P6

44Q

Automotive

(-40°C to 105°C)

20 5V ± 20% AT89C52-20AC

AT89C52-20JC

AT89C52-20PC

AT89C52-20QC

44A

44J

40P6

44Q

Commercial

(0°C to 70°C)

AT89C52-20AI

AT89C52-20JI

AT89C52-20PI

AT89C52-20QI

44A

44J

40P6

44Q

Industrial

(-40°C to 85°C)

AT89C52

4-82

Ordering Information

Speed

(MHz) Power

Supply Ordering Code Package Op eratio n Range

24 5V ± 20% AT89 C52-24AC

AT89C52-24JC

AT89C52-24PC

AT89C52-24QC

44A

44J

40P6

44Q

Commercial

(0°C to 70°C)

AT89C52-24AI

AT89C52-24JI

AT89C52-24PI

AT89C52-24QI

44A

44J

40P6

44Q

Industrial

(-40°C to 85°C)

Package Type

44A 44 Lead, Thin Plastic Gull Wing Quad Flatpack (TQFP)

44J 44 Lead, Plastic J-Leaded Chip Carrier (PLCC)

40P6 40 Lead, 0.600" Wide, Plastic Dual Inline Package (PDIP)

44Q 44 Lead, Plastic Gull Wing Quad Flatpack (PQFP)