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Exar Corporation 48720 Kato Road, Fremont CA, 94538 • (510)668-7017 • www.exar.com SP490,491_101_062711
FEATURES
• +5V Only
• Low Power BiCMOS
• Driver/Receiver Enable (SP491)
• RS-485 and RS-422 Drivers/Receivers
• Pin Compatible with LTC490 and
SN75179 (SP490)
• Pin Compatible with LTC491 and
SN75180 (SP491)
The SP490 is a low power differential line driver/receiver meeting RS-485 and RS-422
standards up to 5Mbps. The SP491 is identical to the SP490 with the addition of driver and
receiver tri-state enable lines. Both products feature ±200mV receiver input sensitivity, over
wide common mode range. The SP490 is available in 8-pin plastic DIP and 8-pin NSOIC
packages for operation over the commercial and industrial temperature ranges. The SP491
is available in 14-pin DIP and 14-pin NSOIC packages for operation over the commercial
and industrial temperature ranges.
SP490 SP491
DESCRIPTION
BLOCK DIAGRAMS
Now Available in Lead Free Packaging
Full Duplex RS-485 Transceivers
SP490/491
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Exar Corporation 48720 Kato Road, Fremont CA, 94538 • (510)668-7017 • www.exar.com SP490,491_101_062711
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 specications below is not implied. Exposure to absolute maximum
rating conditions for extended periods of time may affect reliability.
VCC....................................................................................................+7V
Input Voltages
Drivers................................................-0.5V to (VCC+0.5V)
Receivers..................................................................±14V
Output Voltages
Drivers......................................................................±14V
Receivers...........................................-0.5V to (VCC+0.5V)
Storage Temperature....................................................-65˚C to +150˚
Power Dissipation.....................................................................1000mW
PARAMETERS MIN. TYP. MAX. UNITS CONDITIONS
SP490 DRIVER
DC Characteristics
Differential Output Voltage GND VCC Volts Unloaded; R = ∞ ; see gure 1
Differential Output Voltage 2 VCC Volts With Load; R = 50Ω; (RS422);
see gure 1
Differential Output Voltage 1.5 VCC Volts With Load; R = 27Ω; (RS485); see
gure 1
Change in Magnitude of Driver
Differential Output Voltage for
Complimentary States 0.2 Volts R = 27Ω or R = 50Ω; see gure 1
Driver Common-Mode
Output Voltage 3 Volts R = 27Ω or R = 50Ω; see gure 1
Input High Voltage 2.0 Volts Applies to D
Input Low Voltage 0.8 Volts Applies to D
Input Current ±10 µA Applies to D
Driver Short-Circuit Current
VOUT = HIGH 250 mA -7V ≤ VO ≤ +12V
VOUT = LOW 250 mA -7V ≤ VO ≤ +12V
SP490 DRIVER
AC Characteristics
Maximum Data Rate 5 Mbps
Driver Input to Output 30 60 ns tPLH; RDIFF = 54Ω, CL1 = CL2 = 100pF;
see gures 3 and 6
Driver Input to Output 30 60 ns tPHL; RDIFF = 54Ω, CL1 = CL2 = 100pF;
see gures 3 and 6
Driver Skew 5 ns see gures 3 and 6,
tSKEW = | tDPLH - tDPHL |
Driver Rise or Fall Time 15 40 ns From 10% to 90%; RDIFF = 54Ω,
CL1 = CL2 = 100pF; see gures 3 and 6
SP490 RECEIVER
DC Characteristics
Differential Input Threshold -0.2 +0.2 Volts -7V ≤ VCM ≤ 12V
Input Hysteresis 70 mV VCM = 0V
Output Voltage High 3.5 Volts IO = -4mA, VID = +200mV
Output Voltage Low 0.4 Volts IO = +4mA, VID = -200mV
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 85 mA 0V ≤ VO ≤ VCC
ELECTRICAL CHARACTERISTICS
TMIN to TMAX and VCC = 5V ± 5% unless otherwise noted.
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Exar Corporation 48720 Kato Road, Fremont CA, 94538 • (510)668-7017 • www.exar.com SP490,491_101_062711
TMIN to TMAX and VCC = 5V ± 5% unless otherwise noted.
PARAMETERS MIN. TYP. MAX. UNITS CONDITIONS
SP490 RECEIVER
AC Characteristics
Maximum Data Rate 5 Mbps
Receiver Input to Output 45 150 ns tPLH; RDIFF = 54Ω,
CL1 = CL2
= 100pF; Figures 3 & 8
Receiver Input to Output 45 150 ns tPHL; RDIFF = 54Ω,
CL1 = CL2
= 100pF; Figures 3 & 8
Diff. Receiver Skew ItPLH-tPHLI 13 ns RDIFF = 54Ω; CL1 = CL2 = 100pF;
Figures 3 & 8
POWER REQUIREMENTS
Supply Voltage +4.75 +5.25 Volts
Supply Current 900 µA
ENVIRONMENTAL AND
MECHANICAL
Operating Temperature
Commercial (C_) 0 +70 °C
Industrial (E_) -40 +85 °C
Storage Temperature -65 +150 °C
Package
Plastic DIP (_S)
NSOIC (_N)
Figure 3. Driver/Receiver Timing Test Circuit Figure 4. Driver Timing Test Load #2 Circuit
Figure 1. Driver DC Test Load Circuit Figure 2. Receiver Timing Test Load Circuit
ELECTRICAL CHARACTERISTICS
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Exar Corporation 48720 Kato Road, Fremont CA, 94538 • (510)668-7017 • www.exar.com SP490,491_101_062711
Figure 6. Driver Propagation Delays
Figure 7. Driver Enable and Disable Times
Figure 8. Receiver Propagation Delays
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Exar Corporation 48720 Kato Road, Fremont CA, 94538 • (510)668-7017 • www.exar.com SP490,491_101_062711
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 specications below is not implied. Exposure to
absolute maximum rating conditions for extended periods of time
may affect reliability.
VCC...................................................................................................+7V
Input Voltages
Logic.................................................-0.5V to (VCC+0.5V)
Drivers..............................................-0.5V to (VCC+0.5V)
Receivers................................................................±14V
Output Voltages
Logic................................................-0.5V to (VCC+0.5V)
Drivers....................................................................±14V
Receivers.........................................-0.5V to (VCC+0.5V)
Storage Temperature.....................................................-65˚C to +150
Power Dissipation.................................................................1000mW
TMIN to TMAX and VCC = 5V ± 5% unless otherwise noted.
PARAMETERS MIN. TYP. MAX. UNITS CONDITIONS
SP491 DRIVER
DC Characteristics
Differential Output Voltage GND VCC Volts Unloaded; R = ∞ ; see gure 1
Differential Output Voltage 2 VCC Volts With Load; R = 50Ω; (RS422);
see gure 1
Differential Output Voltage 1.5 VCC Volts With Load; R = 27Ω; (RS485); see
gure 1
Change in Magnitude of Driver
Differential Output Voltage for
Complimentary States 0.2 Volts R = 27Ω or R = 50Ω; see gure 1
Driver Common-Mode
Output Voltage 3 Volts R = 27Ω or R = 50Ω; see gure 1
Input High Voltage 2.0 Volts Applies to D, REB, DE
Input Low Voltage 0.8 Volts Applies to D, REB, DE
Input Current ±10 µA Applies to D, REB, DE
Driver Short-Circuit Current
VOUT = HIGH 250 mA -7V ≤ VO ≤ 12V
VOUT = LOW 250 mA -7V ≤ VO ≤ 12V
SP491 DRIVER
AC Characteristics
Maximum Data Rate 5 Mbps REB = 5V, DE = 5V
Driver Input to Output 30 60 ns tPLH; RDIFF = 54Ω, CL1 = CL2 = 100pF;
see gures 3 and 6
Driver Input to Output 30 60 ns tPHL; RDIFF = 54Ω, CL1 = CL2 = 100pF;
see gures 3 and 6
Driver Skew 5 10 ns see gures 3 and 6,
tSKEW = | tDPLH - tDPHL |
Driver Rise or Fall Time 15 40 ns From 10% to 90%; RDIFF = 54Ω,
CL1 = CL2 = 100pF; see gures 3 and 6
Driver Enable to Output High 40 70 ns CL1 = CL2 = 100pF; see gures
4 and 7; S2 closed
Driver Enable to Output Low 40 70 ns CL1 = CL2 = 100pF; see gures
4 and 7; S1 closed
Driver Disable Time from Low 40 70 ns CL1 = CL2 = 100pF; see gures
4 and 7; S1 closed
Driver Disable Time from High 40 70 ns CL1 = CL2 = 100pF; see gures
4 and 7; S2 closed
ELECTRICAL CHARACTERISTICS
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Exar Corporation 48720 Kato Road, Fremont CA, 94538 • (510)668-7017 • www.exar.com SP490,491_101_062711
TMIN to TMAX and VCC = 5V ± 5% unless otherwise noted.
PARAMETERS MIN. TYP. MAX. UNITS CONDITIONS
SP491 RECEIVER
DC Characteristics
Differential Input Threshold -0.2 +0.2 Volts -7V ≤ VCM ≤ 12V
Input Hysteresis 70 mV VCM = 0V
Output Voltage High 3.5 Volts IO = -4mA, VID = +200mV
Output Voltage Low 0.4 Volts IO = +4mA, VID = -200mV
Three State (high impedance)
Output Current ±1 µA 0.4V ≤ VO ≤ 2.4V; REB = 5V
Input Resistance 12 15 kΩ -7V ≤ VCM ≤ 12V
Input Current (A, B); VIN = 12V ±1.0 mA DE = 0V, VCC = 0V or 5.25V, VIN = 12V
Input Current (A, B); VIN = -7V -0.8 mA DE = 0V, VCC = 0V or 5.25V, VIN = -7V
Short-Circuit Current 85 mA 0V ≤ VO ≤ VCC
SP491
RECEIVER
AC Characteristics
Maximum Data Rate 5 Mbps REB = 0V
Receiver Input to Output 20 45 150 ns tPLH; RDIFF = 54Ω,
CL1 = CL2
= 100pF; Figures 3 & 8
Receiver Input to Output 20 45 150 ns tPHL; RDIFF = 54Ω,
CL1 = CL2
= 100pF; Figures 3 & 8
Diff. Receiver Skew ItPLH-tPHLI 13 ns RDIFF = 54Ω; CL1 = CL2 = 100pF;
Figures 3 & 8
Receiver Enable to Output Low
45 70 ns CRL = 15pF; Figures 2 and 9; S1 closed
Receiver Enable to Output High
45 70 ns CRL = 15pF; Figures 2 and 9; S2 closed
Receiver Disable from Low
45 70 ns CRL = 15pF; Figures 2 and 9; S1 closed
Receiver Disable from High
45 70 ns CRL = 15pF; Figures 2 and 9; S2 closed
POWER REQUIREMENTS
Supply Voltage +4.75 +5.25 Volts
Supply Current 900 µA REB, D = 0V or VCC; DE = VCC
SP491 ENVIRONMENTAL
AND MECHANICAL
Operating Temperature
Commercial (C_) 0 +70 °C
Industrial (E_) -40 +85 °C
Storage Temperature -65 +150 °C
Package
Plastic DIP (_S)
NSOIC (_N)
Figure 9. Receiver Enable and Disable Times
ELECTRICAL CHARACTERISTICS
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Exar Corporation 48720 Kato Road, Fremont CA, 94538 • (510)668-7017 • www.exar.com SP490,491_101_062711
DESCRIPTION
The SP490 and SP491 are full-duplex differen-
tial transceivers that meet the requirements of
RS-485 and RS-422. Fabricated with a
Sipex proprietary BiCMOS process, both
products require a fraction of the power of
older bipolar designs.
The RS-485 standard is ideal for multi-drop
applications or 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) com-
mon mode range to accommodate ground
potential differences. Because RS-485
is a differential interface, data is virtually
immune to noise in the transmission line.
Driver...
The drivers for both the SP490 and SP491
have differential outputs. The typical voltage
output swing with no load will be 0 volts to
+5 volts. With worst case loading of 54Ω
across the differential outputs, the driver can
maintain greater than 1.5V voltage levels.
The driver of the SP491 has a driver enable
control line which is active high. A logic high
on DE (pin 4) of the SP491 will enable
the differential driver outputs. A logic low
on DE (pin 4) of the SP491 will tri-state the
driver outputs. The SP490 does not have a
driver enable.
Receiver...
The receivers for both the SP490 and SP491
have differential inputs with an input sensitiv-
ity as low as ±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
SP490 and SP491 are equipped with the
fail-safe feature. Fail-safe guarantees that
the receiver output will be in a high state
when the input is left unconnected.
The receiver of the SP491 has a receiver
enable control line which is active low. A logic
low on REB (pin 3) of the SP491 will enable
the differential receiver. A logic high on REB
(pin 3) of the SP491 will tri-state the re-
ceiver.
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Exar Corporation 48720 Kato Road, Fremont CA, 94538 • (510)668-7017 • www.exar.com SP490,491_101_062711
PACKAGE: 8 PIN NSOIC
AA1
A2
SIDE VIEW
Seating Plane
SECTION B-B
WITH PLATING
SYMBOL MIN NOM MAX
A 1.35 - 1.75
A1 0.1 - 0.25
A2 1.25 - 1.65
b 0.31 - 0.51
c 0.17 - 0.24
D
E
E1
e
L 0.4 - 1.27
L1
L2
ø 0º - 8º
ø1 5º - 15º
Note: Dimensions in (mm)
8 Pin NSOIC JEDEC MO-012 (AA) Variation
4.90 BSC
6.00 BSC
3.90 BSC
1.27 BSC
1.04 REF
0.25 BSC
Gauge PlaneL1
L
Ø
Ø1
Ø
Seating Plane
L2
VIEW C
TOP VIEW
b
SEE VIEW C
B
B
E
E/2
E1
INDEX AREA
(D/2 X E1/2)
E1/2
D
1
e
c
BASE METAL
b
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Exar Corporation 48720 Kato Road, Fremont CA, 94538 • (510)668-7017 • www.exar.com SP490,491_101_062711
PACKAGE: 14 PIN NSOIC
TOP VIEW
b
Gauge PlaneL1
L
Ø
Ø1
Ø
Seating Plane
L2
VIEW C
SEE VIEW C
B
B
SECTION B-B
WITH PLATING
c
BASE METAL
b
AA1
A2
SYMBOL MIN NOM MAX
A 1.35 - 1.75
A1 0.1 - 0.25
A2 1.25 - 1.65
b 0.31 - 0.51
c 0.17 - 0.25
D
E
E1
e
L 0.4 - 1.27
L1
L2
ø 0º - 8º
ø1 5º - 15º
Note: Dimensions in (mm)
1.27 BSC
1.04 REF
0.25 BSC
14 Pin NSOIC JEDEC MO-012 (AB) Variation
8.65 BSC
6.00 BSC
3.90 BSC
E
E/2
E1
INDEX AREA
(D/2 X E1/2)
E1/2
D
1
e
SIDE VIEW
Seating Plane
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Exar Corporation 48720 Kato Road, Fremont CA, 94538 • (510)668-7017 • www.exar.com SP490,491_101_062711
Model Temperature Range Package
SP490CN-L. ................................................................................... 0˚C to +70˚C ............................................................................... 8-Pin NSOIC
SP490CN-L/TR .............................................................................. 0˚C to +70˚C ............................................................................... 8-Pin NSOIC
SP490EN-L .................................................................................. -40˚C to +85˚C .............................................................................. 8-Pin NSOIC
SP490EN=L/TR............................................................................ -40˚C to +85˚C .............................................................................. 8-Pin NSOIC
SP491CN-L .................................................................................... 0˚C to +70˚C .............................................................................. 14-Pin NSOIC
SP491CN/TR-L .............................................................................. 0˚C to +70˚C .............................................................................. 14-Pin NSOIC
SP491EN-L .................................................................................. -40˚C to +85˚C ............................................................................. 14-Pin NSOIC
SP491EN-L/TR ............................................................................ -40˚C to +85˚C ............................................................................. 14-Pin NSOIC
/TR = Tape and Reel
Pack quantity is 2500 for NSOIC.
ORDERING INFORMATION
Notice
EXAR Corporation reserves the right to make changes to any products contained in this publication in order to improve design, performance or reliabil-
ity. EXAR Corporation assumes no representation that the circuits are free of patent infringement. Charts and schedules contained herein are only for
illustration purposes and may vary depending upon a user's specic application. While the information in this publication has been carefully checked;
no responsibility, however, is assumed for inaccuracies.
EXAR Corporation 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 signicantly affect its safety or effectiveness. Products are not authorized for
use in such applications unless EXAR Corporation receives, in writting, 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 EXAR Corporation is adequately protected under the circumstances.
Copyright 2011 EXAR Corporation
Datasheet May 2011
Send your serial transceiver technical inquiry with technical details to: serialtechsupport@exar.com
Reproduction, in part or whole, without the prior written consent of EXAR Corporation is prohibited.
REVISION HISTORY
Date Revision Description
02/24/05 - Sipex Legacy Data Sheet
07/14/08 1.0.0 Convert to Exar format.
June 2011 1.0.1 Remove minimum entry to Driver Short Circuit Current. Change SP490
receiver propagation typical to 45ns. Remove SP491 receiver short
circuit current minimum entry. Change SP491 receiver propagation
delay MIN and TYP levels to 20 and 45ns respectively. Change SP491
receiver Enable and Disable time TYP and MAX levels to 45 and 70ns
respectively. Change SP491 Supply Current TYP to 900µA. Remove
SP491 driver rise/fall time minimum. Update ordering information.