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Exar Corporation 48720 Kato Road, Fremont CA, 94538 • (510)668-7017 • www.exar.com SP490E,491E_100_052711
FEATURES
• +5V Only
• Low Power BiCMOS
• Driver/Receiver Enable (SP491E)
• RS-485 and RS-422 Drivers/Receivers
• Pin Compatible with LTC490 and
SN75179 (SP490E)
• Pin Compatible with LTC491 and
SN75180 (SP491E)
• Improved ESD Specications:
±15kV Human Body Model
±15kV IEC61000-4-2 Air Discharge
±8kV IEC61000-4-2 Contact Discharge
The SP490E is a low power differential line driver/receiver meeting RS-485 and RS-422
standards up to 10Mbps. The SP491E is identical to the SP490E with the addition of driver
and receiver tri-state enable lines. Both products feature ±200mV receiver input sensitivity,
over wide common mode range. The SP490E is available in 8-pin plastic DIP and 8-pin
NSOIC packages for operation over the commercial and industrial temperature ranges.
The SP491E is available in 14-pin DIP and 14-pin NSOIC packages for operation over the
commercial and industrial temperature ranges.
SP490E SP491E
DESCRIPTION
BLOCK DIAGRAMS
Now Available in Lead Free Packaging
Enhanced Full Duplex RS-485 Transceivers
SP490E/491E
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Exar Corporation 48720 Kato Road, Fremont CA, 94538 • (510)668-7017 • www.exar.com SP490E,491E_100_052711
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 specications 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
SP490E 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
SP490E DRIVER
AC Characteristics
Maximum Data Rate 10 Mbps
Driver Input to Output 30 60 ns tPLH; RDIFF = 54Ω, CL1 = CL2 = 100pF;
see gures 3 and 5
Driver Input to Output 30 60 ns tPHL; RDIFF = 54Ω, CL1 = CL2 = 100pF;
see gures 3 and 5
Driver Skew 5 ns see gures 3 and 5,
tSKEW = | tDPLH - tDPHL |
Driver Rise or Fall Time 15 40 ns From 10% to 90%; RDIFF = 54Ω,
CL1 = CL2 = 100pF; see gures 3 and 5
SP490E 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 SP490E,491E_100_052711
TMIN to TMAX and VCC = 5V ± 5% unless otherwise noted.
PARAMETERS MIN. TYP. MAX. UNITS CONDITIONS
SP490E RECEIVER
AC Characteristics
Maximum Data Rate 10 Mbps
Receiver Input to Output 20 45 100 ns tPLH; RDIFF = 54Ω,
CL1 = CL2
= 100pF; Figures 3 & 7
Receiver Input to Output 20 45 100 ns tPHL; RDIFF = 54Ω,
CL1 = CL2
= 100pF; Figures 3 & 7
Diff. Receiver Skew ItPLH-tPHLI 13 ns RDIFF = 54Ω; CL1 = CL2 = 100pF;
Figures 3 & 7
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 (_P)
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 SP490E,491E_100_052711
Figure 5. Driver Propagation Delays
Figure 6. Driver Enable and Disable Times
Figure 7. Receiver Propagation Delays
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Exar Corporation 48720 Kato Road, Fremont CA, 94538 • (510)668-7017 • www.exar.com SP490E,491E_100_052711
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
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)
TMIN to TMAX and VCC = 5V ± 5% unless otherwise noted.
PARAMETERS MIN. TYP. MAX. UNITS CONDITIONS
SP491E 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
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, RE, DE
Input Low Voltage 0.8 Volts Applies to D, RE, DE
Input Current ±10 µA Applies to D, RE, DE
Driver Short-Circuit Current
VOUT = HIGH 250 mA -7V ≤ VO ≤ 12V
VOUT = LOW 250 mA -7V ≤ VO ≤ 12V
SP491E DRIVER
AC Characteristics
Maximum Data Rate 10 Mbps RE = 5V, DE = 5V
Driver Input to Output 30 60 ns tPLH; RDIFF = 54Ω, CL1 = CL2 = 100pF;
see gures 3 and 5
Driver Input to Output 30 60 ns tPHL; RDIFF = 54Ω, CL1 = CL2 = 100pF;
see gures 3 and 5
Driver Skew 5 10 ns see gures 3 and 5,
tSKEW = | tDPLH - tDPHL |
Driver Rise or Fall Time 15 40 ns From 10% to 90%; RDIFF = 54Ω,
CL1 = CL2 = 100pF; see gures 3 and 5
Driver Enable to Output High 40 70 ns CL1 = CL2 = 100pF; see gures
4 and 6; S2 closed
Driver Enable to Output Low 40 70 ns CL1 = CL2 = 100pF; see gures
4 and 6; S1 closed
Driver Disable Time from Low 40 70 ns CL1 = CL2 = 100pF; see gures
4 and 6; S1 closed
Driver Disable Time from High 40 70 ns CL1 = CL2 = 100pF; see gures
4 and 6; S2 closed
ELECTRICAL CHARACTERISTICS
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Exar Corporation 48720 Kato Road, Fremont CA, 94538 • (510)668-7017 • www.exar.com SP490E,491E_100_052711
TMIN to TMAX and VCC = 5V ± 5% unless otherwise noted.
PARAMETERS MIN. TYP. MAX. UNITS CONDITIONS
SP491E 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; RE = 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
SP491E
RECEIVER
AC Characteristics
Maximum Data Rate 10 Mbps RE = 0V
Receiver Input to Output 20 45 100 ns tPLH; RDIFF = 54Ω,
CL1 = CL2
= 100pF; Figures 3 & 7
Receiver Input to Output 20 45 100 ns tPHL; RDIFF = 54Ω,
CL1 = CL2
= 100pF; Figures 3 & 7
Diff. Receiver Skew ItPLH-tPHLI 13 ns RDIFF = 54Ω; CL1 = CL2 = 100pF;
Figures 3 & 7
Receiver Enable to Output Low
45 70 ns CRL = 15pF; Figures 2 and 8; S1 closed
Receiver Enable to Output High
45 70 ns CRL = 15pF; Figures 2 and 8; S2 closed
Receiver Disable from Low
45 70 ns CRL = 15pF; Figures 2 and 8; S1 closed
Receiver Disable from High
45 70 ns CRL = 15pF; Figures 2 and 8; S2 closed
POWER REQUIREMENTS
Supply Voltage +4.75 +5.25 Volts
Supply Current 900 µA RE, D = 0V or VCC; DE = VCC
SP491E ENVIRONMENTAL
AND MECHANICAL
Operating Temperature
Commercial (_C_) 0 +70 °C
Industrial (_E_) -40 +85 °C
Storage Temperature -65 +150 °C
Package
Plastic DIP (_P)
NSOIC (_N)
Figure 8. 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 SP490E,491E_100_052711
DESCRIPTION
The SP490E and SP491E a r e
fu ll - du pl e x d iffe re n ti al t ra nsc ei v -
ers that meet the requirements of
RS-485 and RS-422. Fabricated with a Exar
proprietary BiCMOS process, both products
require a fraction of the power of older bi-
polar 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 SP490E and SP491E
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 SP491E has a driver enable
control line which is active high. A logic high
on DE (pin 4) of the SP491E will enable
the differential driver outputs. A logic low
on DE (pin 4) of the SP491E will tri-state the
driver outputs. The SP490E does not have
a driver enable.
Receiver...
The receivers for both the SP490E and
SP491E have differential inputs with an
input sensitivity 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 be-
tween systems. The receivers for both the
SP490E and SP491E 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 SP491E has a receiver
enable control line which is active low. A logic
low on REB (pin 3) of the SP491E will enable
the differential receiver. A logic high on REB
(pin 3) of the SP491E will tri-state the re-
ceiver.
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Exar Corporation 48720 Kato Road, Fremont CA, 94538 • (510)668-7017 • www.exar.com SP490E,491E_100_052711
ESD TOLERANCE
The SP490E/SP491E devices incorporates
ruggedized ESD cells on all driver output
and receiver input pins. The ESD structure
is improved over our previous family for
more rugged applications and environments
sensitive to electro-static discharges and
associated transients. The improved ESD
tolerance is at least ±15kV without damage
nor latch-up.
There are different methods of ESD testing
applied:
a) MIL-STD-883, Method 3015.7
b) IEC61000-4-2 Air-Discharge
c) IEC61000-4-2 Direct Contact
The Human Body Model has been the
generally accepted ESD testing method
for semiconductors. This method is also
specied in MIL-STD-883, Method 3015.7
for ESD testing. The premise of this ESD test
is to simulate the human body’s potential to
store electro-static energy and discharge it
to an integrated circuit. The simulation is
performed by using a test model as shown
in Figure 9. This method will test the IC’s
capability to withstand an ESD transient
during normal handling such as in manu-
facturing areas where the ICs tend to be
handled frequently.
The IEC-61000-4-2, formerly IEC801-2, is
generally used for testing ESD on equipment
and systems. For system manufacturers,
they must guarantee a certain amount of ESD
protection since the system itself is exposed
to the outside environment and human pres-
ence. The premise with IEC61000-4-2 is that
the system is required to withstand an amount
of static electricity when ESD is applied to
points and surfaces of the equipment that
are accessible to personnel during normal
usage. The transceiver IC receives most
of the ESD current when the ESD source is
applied to the connector pins. The test circuit
for IEC61000-4-2 is shown on Figure 10.
There are two methods within IEC61000-4-2,
the Air Discharge method and the Contact
Discharge method.
With the Air Discharge Method, an ESD
voltage is applied to the equipment under
test (EUT) through air. This simulates an
electrically charged person ready to connect
a cable onto the rear of the system only to
nd an unpleasant zap just before the person
touches the back panel. The high energy
potential on the person discharges through
an arcing path to the rear panel of the system
before he or she even touches the system.
This energy, whether discharged directly or
through air, is predominantly a function of the
discharge current rather than the discharge
voltage. Variables with an air discharge such
as approach speed of the object carrying the
ESD potential to the system and humidity
will tend to change the discharge current.
For example, the rise time of the discharge
current varies with the approach speed.
The Contact Discharge Method applies the
ESD current directly to the EUT. This method
was devised to reduce the unpredictability
of the ESD arc. The discharge current rise
time is constant since the energy is directly
transferred without the air-gap arc. In situ-
ations such as hand held systems, the ESD
charge can be directly discharged to the
equipment from a person already holding
the equipment. The current is transferred
on to the keypad or the serial port of the
equipment directly and then travels through
the PCB and nally to the IC.
The circuit model in Figures 9 and 10 repre-
sent the typical ESD testing circuit used for
all three methods. The CS is initially charged
with the DC power supply when the rst
switch (SW1) is on. Now that the capacitor
is charged, the second switch (SW2) is on
while SW1 switches off. The voltage stored
in the capacitor is then applied through RS,
the current limiting resistor, onto the device
under test (DUT). In ESD tests, the SW2
switch is pulsed so that the device under
test receives a duration of voltage.
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Exar Corporation 48720 Kato Road, Fremont CA, 94538 • (510)668-7017 • www.exar.com SP490E,491E_100_052711
For the Human Body Model, the current
limiting resistor (RS) and the source capacitor
(CS) are 1.5kΩ an 100pF, respectively. For
IEC-61000-4-2, the current limiting resistor
(RS) and the source capacitor (CS) are 330Ω
an 150pF, respectively.
Figure 11. ESD Test Waveform for IEC61000-4-2
t = 0ns t = 30ns
0A
15A
30A
I →
t →
Figure 9. ESD Test Circuit for Human Body Model
Figure 10. ESD Test Circuit for IEC61000-4-2
R
C
Device
Under
Test
DC Power
Source
C
S
R
S
SW1 SW2
R
S
and
R
V
add up to 330Ω for IEC61000-4-2.
R
C
Device
Under
Test
DC Power
Source
C
S
R
S
SW1 SW2
R
V
Contact-Discharge Model
The higher CS value and lower RS value in
the IEC61000-4-2 model are more stringent
than the Human Body Model. The larger
storage capacitor injects a higher voltage
to the test point when SW2 is switched on.
The lower current limiting resistor increases
the current charge onto the test point.
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Exar Corporation 48720 Kato Road, Fremont CA, 94538 • (510)668-7017 • www.exar.com SP490E,491E_100_052711
MODEL Air Discharge Direct Contact Level
Driver Outputs ±15kV ±15kV ±8kV 4
Receiver Inputs ±15kV ±15kV ±8kV 4
Sp490E, Sp491E
Family
Tabke 1. Transceiver ESD Tolerance Levels
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Exar Corporation 48720 Kato Road, Fremont CA, 94538 • (510)668-7017 • www.exar.com SP490E,491E_100_052711
PACKAGE: 8 PIN NSOIC
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Exar Corporation 48720 Kato Road, Fremont CA, 94538 • (510)668-7017 • www.exar.com SP490E,491E_100_052711
PACKAGE: 14 PIN NSOIC
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Exar Corporation 48720 Kato Road, Fremont CA, 94538 • (510)668-7017 • www.exar.com SP490E,491E_100_052711
PACKAGE: 8 PIN PDIP
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Exar Corporation 48720 Kato Road, Fremont CA, 94538 • (510)668-7017 • www.exar.com SP490E,491E_100_052711
PACKAGE: 14 PIN PDIP
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Exar Corporation 48720 Kato Road, Fremont CA, 94538 • (510)668-7017 • www.exar.com SP490E,491E_100_052711
SP490ECN-L. .................................................................................0˚C to +70˚C ............................................................................... 8-Pin NSOIC
SP490ECN-L/TR ............................................................................ 0˚C to +70˚C ............................................................................... 8-Pin NSOIC
SP490ECP-L ..................................................................................0˚C to +70˚C .................................................................................8-Pin PDIP
SP490EEN-L ................................................................................ -40˚C to +85˚C .............................................................................. 8-Pin NSOIC
SP490EEN-L/TR .......................................................................... -40˚C to +85˚C .............................................................................. 8-Pin NSOIC
SP490EEP-L ................................................................................ -40˚C to +85˚C ................................................................................8-Pin PDIP
SP491ECN-L ..................................................................................0˚C to +70˚C .............................................................................. 14-Pin NSOIC
SP491ECN-L/TR ............................................................................ 0˚C to +70˚C .............................................................................. 14-Pin NSOIC
SP491ECP-L ..................................................................................0˚C to +70˚C ................................................................................14-Pin PDIP
SP491EEN-L ................................................................................ -40˚C to +85˚C ............................................................................. 14-Pin NSOIC
SP491EEN-L/TR .......................................................................... -40˚C to +85˚C ............................................................................. 14-Pin NSOIC
SP491EEP-L ................................................................................ -40˚C to +85˚C ...............................................................................14-Pin PDIP
Note: /TR = Tape and Reel
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 specic 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 signicantly 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
2000 14 Sipex Legacy Data Sheet
May 2011 1.0.0 Convert to Exar format. Remove driver propagation delay minimum and
driver rise/fall time minimum entry for SP490E and SP491E. Update
ESD rating to IEC61000-4-2. Update ordering information.
