3.3V Low Power Full-Duplex RS-485 Transceivers
with 10Mbps Data Rate
SP3490 / SP3491
1/12
REV 1.0.3
FEATURES
Full-duplex RS-485 and RS-422
transceivers
Operates from a single 3.3V supply
Interoperable with 5.0V logic
Driver/receiver tri-state enable lines
(SP3491)
-7V to 12V common-mode input voltage
range
±200mV receiver input sensitivity
Allows up to 32 transceivers on the serial
bus
Compatability with LTC490 and SN75179
(SP3490)
Compatability with LTC491 and SN75180
(SP3491)
Description
The SP3490 and SP3491 devices are 3.3V low power full-duplex
transceivers that meet the specifications of the RS-485 and RS-422
serial protocols. These devices are pin-to-pin compatible with the
MaxLinear SP490 and SP491 devices as well as popular industry
standards. The SP3490 and SP3491 feature MaxLinear’s BiCMOS
process, allowing low power operation without sacrificing performance.
The SP3490 and SP3491 meet the electrical specifications of the
RS-485 and RS-422 serial protocols up to 10Mbps under load. The
SP3491 is identical to the SP3490 with the addition of driver and
reciveiver tri-state enable lines.
Block Diagrams
Ordering Information - Back Page
VCC
D
R
NC
A
B
Z
Y
R
NC
NC
DE
REB
GND
GND
2
1
3
4
5
6
78
9
10
11
12
13
14
D
VCC
D
R
A
B
Z
Y
R
GND
2
1
3
4
5
6
7
8
D
SP3490 SP3491
SP3490 / SP3491
2/12
REV 1.0.3
Absolute Maximum Ratings
These are stress ratings only and functional operation of the
device at these ratings or any other above those indicated
in the operation sections of the specifications below is not
implied. Exposure to absolute maximum rating conditions
for extended periods of time may affect reliability.
VCC ............................................................................... 6.0V
Input Voltages
Logic ..................................... -0.3V to 6.0V
Drivers .................................. -0.3V to 6.0V
Receivers ...........................................±14V
Output Voltages
Drivers ...............................................±14V
Receivers .............................. -0.3V to 6.0V
Storage Temperature .................................-65˚C to +150˚C
Maximum Junction Temperature, TJ ..........................125˚C
Power Dissipation
8-pin NSOIC ............................................................ 600mW
(derate 6.90mW/°C above +70°C)
14-pin NSOIC ......................................................... 700mW
(derate 8.33mW/°C above +70°C)
Electrical Characteristics
TAMB = TMIN to TMAX and VCC = 3.3V ±5% unless otherwise noted.
PARAMETERS MIN. TYP. MAX. UNITS CONDITIONS
SP3490 Driver DC Characteristics
Dierential output voltage Vcc V Unloaded; R = ∞Ω ; Figure 1
Dierential output voltage 2 Vcc V With load; R = 50Ω (RS-422); Figure 1
Dierential output voltage 1.5 Vcc V With load; R = 27Ω (RS-485); Figure 1
Change in magnitude of driver
dierential output voltage for
complimentary states
0.2 VR = 27Ω or R = 50Ω; Figure 1
Driver common-mode output voltage 3 V R = 27Ω or R = 50Ω; Figure 1
Input high voltage 2.0 V
Input low voltage 0.8 V
Input current ±10 µA
Driver short circuit current
VOUT = HIGH ±250 mA -7V ≤ VO ≤ 12V; Figure 8
Driver short circuit current
VOUT = LOW ±250 mA -7V ≤ VO ≤ 12V; Figure 8
SP3490 Driver AC Characteristics
Maximum data rate 10 Mbps
Driver input to output, tPLH 20 40 60 ns R = 27Ω, Figures 2 & 9
Driver input to output, tPHL 20 40 60 ns R = 27Ω, Figures 2 & 9
Operating Conditions
Package Power Dissipation
8-pin NSOIC ѲJA ................................................ 128.4˚C/W
14-pin NSOIC ѲJA ................................................ 88.2˚C/W
ESD Rating
Human Body Model (HBM) .......................................... ±2kV
SP3490 / SP3491
3/12
REV 1.0.3
Electrical Characteristics (Continued)
TAMB = TMIN to TMAX and VCC = 3.3V ±5% unless otherwise noted.
PARAMETERS MIN. TYP. MAX. UNITS CONDITIONS
SP3490 Driver AC Characteristics (Continued)
Dierential driver skew 2ns |tPHL(Y)- tPLH(Y)|, |tPHL(Z)- tPLH(Z)|,
Figures 2 and 9
Driver rise or fall time 5 20 ns From 10%-90%; Figures 3 and 10
SP3490 Receiver DC Characteristics
Dierential input threshold -0.2 0.2 Volts -7V ≤ VCM ≤ 12V
Input hysteresis 25 mV VCM = 0V
Output voltage HIGH Vcc-0.4 Volts VID = 200mV, IO = -1.5mA
Output voltage LOW 0.4 Volts VID = -200mV, IO = 2.5mA
Input resistance 12 15 kΩ -7V ≤ VCM ≤ 12V
Input current (A, B); VIN = 12V 1.0 mA VIN = 12V
Input current (A, B); VIN = -7V -0.8 mA VIN = -7V
Short circuit current 60 mA 0V ≤ VO ≤ VCC
SP3490 Receiver AC Characteristics
Maximum data rate 10 Mbps
Receiver input to output, tPLH 40 70 120 ns Figures 6 and 12
Receiver input to output, tPLH 85 ns TAMB = 25°C, Vcc = 3.3V, Figures 6 and 12
Receiver input to output, tPHL 40 70 120 ns Figures 6 and 12
Receiver input to output, tPHL 85 ns TAMB = 25°C, Vcc = 3.3V, Figures 6 and 12
Dierential receiver skew 4 ns |tPHL(A)- tPLH(A)|, |tPHL(B)- tPLH(B)|,
Figures 6 and 12
Power Requirements
Supply Voltage 3.0 3.3 3.6 V
Supply Current 1000 2000 µA D = 0V or VCC
ESD Protection for D, R, A, B, Y and
Z pins ±2kV Human Body Model
SP3490 / SP3491
4/12
REV 1.0.3
PARAMETERS MIN. TYP. MAX. UNITS CONDITIONS
SP3491 Driver DC Characteristics
Dierential output voltage Vcc V Unloaded; R = ∞Ω ; Figure 1
Dierential output voltage 2 Vcc V With load; R = 50Ω (RS-422); Figure 1
Dierential output voltage 1.5 Vcc V With load; R = 27Ω (RS-485); Figure 1
Change in magnitude of driver
dierential output voltage for
complimentary states
0.2 VR = 27Ω or R = 50Ω; Figure 1
Driver common-mode output voltage 3 V R = 27Ω or R = 50Ω; Figure 1
Input high voltage 2.0 VApplies to DE, D, REB
Input low voltage 0.8 VApplies to DE, D, REB
Input current ±10 µA Applies to DE, D, REB
Driver short circuit current
VOUT = HIGH ±250 mA -7V ≤ VO ≤ 12V; Figure 8
Driver short circuit current
VOUT = LOW ±250 mA -7V ≤ VO ≤ 12V; Figure 8
SP3491 Driver AC Characteristics
Maximum data rate 10 Mbps
Driver input to output, tPLH 20 40 60 ns Figures 2 & 9
Driver input to output, tPHL 20 40 60 ns Figures 2 & 9
Dierential driver skew 2ns |tPHL(Y)- tPLH(Y)|, |tPHL(Z)- tPLH(Z)|,
Figures 2 and 9
Driver rise or fall time 5 20 ns From 10%-90%; Figures 3 and 10
Driver enable to output HIGH 52 120 ns Figures 4 and 11
Driver enable to output LOW 60 120 ns Figures 5 and 11
Driver disable from LOW 40 120 ns Figures 5 and 11
Driver disable from HIGH 60 120 ns Figures 4 and 11
Electrical Characteristics, Continued
TAMB = TMIN to TMAX and VCC = 3.3V ±5% unless otherwise noted
SP3490 / SP3491
5/12
REV 1.0.3
PARAMETERS MIN. TYP. MAX. UNITS CONDITIONS
SP3491 Receiver DC Characteristics
Dierential input threshold -0.2 0.2 Volts -7V ≤ VCM ≤ 12V
Input hysteresis 25 mV VCM = 0V
Output voltage HIGH Vcc-0.4 Volts VID = 200mV, IO = -1.5mA
Output voltage LOW 0.4 Volts VID = -200mV, IO = 2.5mA
Three-State ( High Impedance)
Output Current ±1µA 0V ≤ VO ≤ Vcc; REB = Vcc
Input resistance 12 15 kΩ -7V ≤ VCM ≤ 12V
Input current (A, B); VIN = 12V 1.0 mA DE = 0V, VCC = 0V or 3.6V,
VIN = 12V
Input current (A, B); VIN = -7V -0.8 mA DE = 0V, VCC = 0V or 3.6V,
VIN = -7V
Short circuit current 60 mA 0V ≤ VO ≤ VCC
SP3491 Receiver AC Characteristics
Maximum data rate 10 Mbps REB = 0V, DE = 0V
Receiver input to output, tPLH 40 70 120 ns Figures 6 and 12
Receiver input to output, tPLH 85 ns TAMB = 25°C, Vcc = 3.3V, Figures 6 and 12
Receiver input to output, tPHL 40 70 120 ns Figures 6 and 12
Receiver input to output, tPHL 85 ns TAMB = 25°C, Vcc = 3.3V, Figures 6 and 12
Dierential receiver skew 4 ns |tPHL(A)- tPLH(A)|, |tPHL(B)- tPLH(B)|,
Figures 6 and 12
Receiver enable to output LOW 65 150 ns Figures 7 and 13; S1 Closed, S2 open
Receiver enable to output HIGH 65 150 ns Figures 7 and 13; S2 Closed, S1 open
Receiver disable from LOW 65 200 ns Figures 7 and 13; S1 Closed, S2 open
Receiver disable from HIGH 65 200 ns Figures 7 and 13; S2 Closed, S1 open
Power Requirements
Supply voltage 3.0 3.6 V
Supply current 1000 2000 µA REB, D = 0V or VCC; DE = VCC
Supply current 800 1500 µA DE = 0V
ESD protection for R, D, DE, REB, A,
B, Y and Z pins ±2kV Human Body Model
Electrical Characteristics, Continued
TAMB = TMIN to TMAX and VCC = 3.3V ±5% unless otherwise noted
SP3490 / SP3491
6/12
REV 1.0.3
Pin Number Pin Name Description
1 VCC Positive supply 3.00V < Vcc < 3.60V
2 R Receiver output
3 D Driver Input
4 GND Ground connection
5 Y Non-inverting driver output
6 Z Inverting driver output
7 B Inverting receiver Input
8 A Non-inverting receiver input
SP3490
Pinout (Top View)
Pin Functions
VCC
D
RA
B
Z
Y
R
GND
2
1
3
4
5
6
7
8
D
V
CC
D
R
NC
A
B
Z
Y
R
NC
NC
DE
REB
GND
GND
2
1
3
4
5
6
78
9
10
11
12
13
14
D
Pin Number Pin Name Description
1 NC No connect(1)
2 R Receiver output
3 REB Receiver output enable active LOW
4 DE Driver output enable active HIGH
5 D Driver input
6 GND Ground connection
7 GND Ground connection
8 NC No connect(1)
9 Y Non-inverting driver output
10 Z Inverting driver output
11 B Inverting receiver input
12 A Non-Inverting receiver input
13 NC No connect(1)
14 VCC Positive supply 3.00V < Vcc < 3.60V
Note:
1. Not internally bonded, can be connected to Vcc without harm.
SP3491
Pinout (Top View)
SP3490 / SP3491
7/12
REV 1.0.3
Test Circuits
Figure 1: Driver DC Test Load Circuit Figure 2: Driver Propagation Delay Test Circuit
Figure 3: Driver Differential Output Delay and
Transition Time Circuit.
Figure 4: Driver Enable and Disable Timing Circuit,
Output High
Figure 7: Receiver Enable and Disable Timing Circuit Figure 8: Driver Short Circuit Current Limit Test
Figure 5: Driver Enable and Disable Timing Circuit,
Output Low
Figure 6: Receiver Propagation Delay Test Circuit
GENERATOR
(NOTE 1) 50Ω
V
CC
S1
V
DM
R
L
= 27Ω
OUT
C
L
= 15pF
(NOTE 2)
V
OM
= ≈ 1.5V
V
OH
+ V
OL
2
D
R
RV
OC
D
Vcc
V
OD
GENERATOR
(NOTE 1) 50Ω
C
L
OUT
D
V
CC
R
L
=
60Ω
C
L
= 15pF (NOTE 2)
GENERATOR
(NOTE 1) 50Ω
S1
RL = 110Ω
OUT
CL = 50pF
(NOTE 2)
D
0V OR 3V
VCC
GENERATOR
(NOTE 1) 50Ω
S1
R
L
= 110Ω
OUT
C
L
= 50pF
(NOTE 2)
V
OM
= ≈ 1.5V
V
OH
+ V
OL
2
D
GENERATOR
(NOTE 1) 50Ω
1.5V
0V
V
ID
ROUT
CL = 15pF
(NOTE 2)
V
OM
= V
CC
2
1.5V
-1.5V
S3
V
ID
GENERATOR
(NOTE 1)
50Ω
C
L
= 15pF
(NOTE 2)
R
1k
S1
S2
V
CC
A/Y
D
DI = 0 or Vcc
B/Z
DE = 0 or Vcc
IOS D
100Ω
-7V to +12V V
SP3490 / SP3491
8/12
REV 1.0.3
Switching Waveforms
Figure 9: Driver Propagation Delay Waveforms Figure 10: Driver Differential Output Delay and
Transition Time Waveforms
Figure 11: Driver Enable and Disable Timing Waveforms Figure 12: Receiver Propagation Delay Waveforms
Figure 13: Receiver Enable and Disable Waveforms
0V
VOH
tPLH tPHL
V
OM
tPHL tPLH
3V
VOL
VOH
1.5V 1.5V
INPUT
Y OUTPUT
V
OM
Z OUTPUT
VOL
V
OM
V
OM
V
OM
= V
OH
+ V
OL
2≈ 1.5V
IN
1.5V
tDO1
1.5V
tDO2
3V
0V
OUT
50% 50%
10% 10%
90% 90%
tTD
t
TD
2.0V
-2.0V
0V
V
OH
t
PZH
0.25V
t
PHZ
V
OM
t
PZL
t
PLZ
3V
V
OL
V
CC
1.5V 1.5V
DE
OUTPUT
HIGH
V
OM
0.25V
0V
OUTPUT
LOW
V
OM
= V
OH
+ V
OL
2≈ 1.5V
3V
0V
V
CC
t
RPLH
1.5V
t
RPHL
V
OM
V
OM
0V
1.5V
INPUT
OUTPUT
V
OM
= V
CC
2
3V
0V
tPRHZ
1.5V
tPRZH
tPRSH
1.5V
1.5V
10%
0V
VOH
REB
OUTPUT
S1 is open
S2 is closed
S3 = 1.5V
3V
0V
tPRLZ
1.5V
tPRZL
tPRSL
1.5V
1.5V
10%
VCC
REB
OUTPUT
S1 is closed
S2 is open
S3 = -1.5V
VOL
NOTES
1. The input pulse is supplied by a generator with the following characteristics:
PRR = 250kHz, 50% duty cycle, tR < 6.0ns, ZO = 50Ω.
2. CL includes probe and stray capacitance.
SP3490 / SP3491
9/12
REV 1.0.3
Description
The SP3490 and SP3491 are two members in the family
of 3.3V low power full-duplex transceivers that meet the
electrical specifications of the RS-485 and RS-422 serial
protocols. These devices are pin-to-pin compatible with the
MaxLinear SP490 and SP491 devices as well as popular
industry standards. The SP3490 and SP3491 feature
MaxLinear’s BiCMOS process allowing low power operation
without sacrificing performance.
The RS-485 standard is ideal for multi-drop applications and
for long-distance interfaces. RS-485 allows up to 32 drivers
and 32 receivers to be connected to a data bus, making
it an ideal choice for multi-drop applications. Since the
cabling can be as long as 4,000 feet, RS-485 transceivers
are equipped with a wide (-7V to 12V) common mode range
to accommodate ground potential differences. Because
RS-485 is a differential interface, data is virtually immune to
noise in the transmission line.
Drivers
The drivers for both the SP3490 and SP3491 have
differential outputs. The typical voltage output swing with
no load will be 0 volts to Vcc. With worst case loading of
54Ω across the differential outputs, the drivers can maintain
greater than 1.5V voltage levels.
The driver of the SP3491 has a driver enable control line
which is active HIGH. A logic HIGH on DE (pin 4) of the
SP3491 will enable the differential driver outputs. A logic
LOW on the DE (pin 4) will tri-state the driver outputs. The
SP3490 does not have a driver enable.
Receivers
The receivers of the SP3490 and SP3491 have differential
inputs with an input sensitivity of ±200mV. Input impedance
of the receivers is typically 15kΩ (12kΩ minimum). A wide
common mode range of -7V to 12V allows for large ground
potential differences between systems. The receivers for
both the SP3490 and SP3491 are equipped with a fail-
safe feature that guarantees the receiver output will be in a
HIGH state when the input is left unconnected.
The receiver of the SP3491 has a enable control line which
is active LOW. A logic LOW on REB (pin 3) of the SP3491
will enable the differential receiver. A logic HIGH on REB
(pin 3) of the SP3491 will tri-state the receiver.
SP3490 / SP3491
10/12
REV 1.0.3
Mechanical Dimensions
NSOIC8
Drawing No:
Revision: A
Side View
Top View
Front View
POD-00000108
SP3490 / SP3491
11/12
REV 1.0.3
Mechanical Dimensions
NSOIC14
Drawing No: POD-00000109
Revision: A
Side View
Top View
Front View
SP3490 / SP3491
The content of this document is furnished for informational use only, is subject to change without notice, and should not be construed as a commitment by MaxLinear, Inc.. MaxLinear, Inc. assumes
no responsibility or liability for any errors or inaccuracies that may appear in the informational content contained in this guide. Complying with all applicable copyright laws is the responsibility of the
user. Without limiting the rights under copyright, no part of this document may be reproduced into, stored in, or introduced into a retrieval system, or transmitted in any form or by any means (electronic,
mechanical, photocopying, recording, or otherwise), or for any purpose, without the express written permission of MaxLinear, Inc.
Maxlinear, Inc. does not recommend the use of any of its products in life support applications where the failure or malfunction of the product can reasonably be expected to cause failure of the life support
system or to significantly affect its safety or effectiveness. Products are not authorized for use in such applications unless MaxLinear, Inc. receives, in writing, assurances to its satisfaction that: (a) the
risk of injury or damage has been minimized; (b) the user assumes all such risks; (c) potential liability of MaxLinear, Inc. is adequately protected under the circumstances.
MaxLinear, Inc. may have patents, patent applications, trademarks, copyrights, or other intellectual property rights covering subject matter in this document. Except as expressly provided in any written
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Company and product names may be registered trademarks or trademarks of the respective owners with which they are associated.
© 2017 MaxLinear, Inc. All rights reserved
SP3490_SP3491_DS_090617 12/12
REV 1.0.3
Corporate Headquarters:
5966 La Place Court
Suite 100
Carlsbad, CA 92008
Tel.:+1 (760) 692-0711
Fax: +1 (760) 444-8598
www.maxlinear.com
High Performance Analog:
48720 Kato Road
Fremont, CA 94538
Tel.: +1 (510) 668-7000
Fax: +1 (510) 668-7001
Email: serialtechsupport@exar.com
www.exar.com
Ordering Information(1)
Part Number Operating Temperature Range Lead-Free Package Packaging Method
SP3490CN-L/TR 0°C to 70°C
Yes(2)
8-pin NSOIC
Reel
SP3490EN-L
-40°C to 85°C
Tube
SP3490EN-L/TR Reel
SP3491CN-L
0°C to 70°C
14-pin NSOIC
Tube
SP3491CN-L/TR Reel
SP3491EN-L
-40°C to 85°C
Tube
SP3491EN-L/TR Reel
NOTE:
1. Refer to www.exar.com/SP3490 and www.exar.com/SP3491 for most up-to-date Ordering Information.
2. Visit www.exar.com for additional information on Environmental Rating.
Revision History
Revision Date Description
10/11/02 -- Legacy Sipex Datasheet
06/08/10 1.0.0
Convert to Exar Format. Update ordering information as a result of discontinued Lead type
package options per PDN 081126-01. Change revision to 1.0.0. Add new Figure 8 - Driver
Short Circuit Current Limit Test Circuit
9/14/10 1.0.1 Correct package type for SP3491 options in ordering table from 8 pin NSOIC to 14 pin NSOIC
10/27/10 1.0.2 Add ESD protection levels of +/-2kV. Remove SP3490 Supply Current rating for DE = 0V (No
driver enable for SP3490).
09/06/17 1.0.3
Update to MaxLinear logo. Update pin description table to include note on NC pin. Remove
GND from Dierential Output Voltage min (page 2 and 4). Added maximum junction
temperature, package power dissipation and ESD rating. Update format and ordering
information table.
