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Exar Corporation 48720 Kato Road, Fremont CA, 94538 • 510-668-7017 • www.exar.com SP3494_100_071012
DESCRIPTION
• Operates From A Single +3.3V Supply
• Interoperable With +5.0V Logic
• +/-200mV Receiver Input Sensitivity
• -7V to +12V Common-Mode Input Voltage Range
• Allows Up To 32 transceivers On The Serial Bus
• Driver/Receiver Enable Lines
• 10µA Low-Power Shutdown Mode
• Compatibility with the MAX3486 and 75176 Industry
Standard Pinout
SP3494
+3.3V Low Power
RS-485/RS-422 Transceiver
The SP3494 device is a +3.3V low power half-duplex transceiver that meets the specications
of the RS-485 and RS-422 serial protocols. This device is pin-to-pin compatible with the Exar
SP3481 device as well as other popular industry standards. The SP3494 features the Exar
BiCMOS process, allowing low power operation without sacricing performance. The partially
slew-rate limited drivers minimize EMI and reduce reections caused by improperly terminated
cables allowing error-free data transmission.The SP3494 is a half-duplex partially slew-rate
limited transceiver that will deliver a data transmission rate up to 2.5Mbps. The SP3494 is
equipped with a low-power shutdown mode and driver/receiver high-Z enable lines.
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Exar Corporation 48720 Kato Road, Fremont CA, 94538 • 510-668-7017 • www.exar.com SP3494_100_071012
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.....................................................................+6.0V
Input Voltages
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
Power Dissipation
8-pin NSOIC...................................................600mW
(derate 6.90mW/ºC above +70ºC)
ELECTRICAL CHARACTERISTICS
TAMB = TMIN to TMAX and VCC = +3.3V +/-5% unless otherwise noted.
PARAMETERS MIN. TYP. MAX. UNITS CONDITIONS
SP3494 DRIVER
DC Characteristics
Differential Output Voltage GND Vcc Volts Unloaded; R = ∞Ω ; Figure 1
Differential Output Voltage 2 Vcc Volts With Load; R = 50Ω (RS-422);
Figure 1
Differential Output Voltage 1.5 Vcc Volts With Load; R = 27Ω (RS-485);
Figure 1
Change in Magnitude of Driver
Differential Output Voltage for
Complimentary states
0.2 Volts R = 27Ω or R = 50Ω; Figure 1
Driver Common-Mode Output
Voltage
3 Volts R = 27Ω or R = 50Ω; Figure 1
Input High Voltage 2.0 Volts Applies to DE, DI, RE
Input Low Voltage 0.8 Volts Applies to DE, DI, RE
Input Current +/-10 µA Applies to DE, DI, RE
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
SP3494 DRIVER
AC Characteristics
Maximum Data Rate 2.5 Mbps RE = VCC, DE = VCC
Driver Input to Output, tPLH 20 45 75 ns Figures 2 & 9
Driver Input to Output, tPHL 20 45 75 ns Figures 2 & 9
Differential Driver Skew 10 ns |tDO1- tDO2|, Figures 2 and 10
Driver Rise or Fall Time 30 70 ns From 10%-90%; Figures 3 and 10
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Exar Corporation 48720 Kato Road, Fremont CA, 94538 • 510-668-7017 • www.exar.com SP3494_100_071012
PARAMETERS MIN. TYP. MAX. UNITS CONDITIONS
SP3494 DRIVER AC Characteristics continued
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 Time from Low 40 120 ns Figures 5 and 11
Driver Disable Time from High 60 120 ns Figures 4 and 11
SP3494 RECEIVER
DC Characteristics
Differential Input Threshold -0.2 +0.2 Volts -7V ≤ VCM ≤ +12V
Input Hysteresis 20 mV VCM = 0V
Output Voltage HIGH Vcc-0.4 Volts VID = +200mV, -1.5mA
Output Voltage LOW 0.4 Volts VID = -200mV, 2.5mA
Three-State (High Impedance)
Output Current
+/-1 µA 0V ≤ VO ≤ VCC; RE = 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 7 60 mA 0V ≤ VCM ≤ VCC
SP3485 RECEIVER
AC Characteristics
Maximum Data Rate 2.5 Mbps RE = 0V, DE = 0V
Receiver Input to Output, tPLH 40 70 100 ns Figures 6 and 12
Receiver Input to Output, tPHL 40 70 100 ns Figures 6 and 12
Differential Receiver Skew 10 ns tRSKEW = |tRPHL- tRPLH|,
Figures 6 and 12
Receiver Enable to Output Low 35 60 ns Figures 7 and 13,
S1 closed, S2 open
Receiver Enable to Output High 35 60 ns Figures 7 and 13,
S2 closed, S1 open
Receiver Disable from Low 35 60 ns Figures 7 and 13,
S1 closed, S2 open
Receiver Disable from High 35 60 ns Figures 7 and 13,
S2 closed, S1 open
ELECTRICAL CHARACTERISTICS
TAMB = TMIN to TMAX and VCC = +3.3V +/-5% unless otherwise noted.
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Exar Corporation 48720 Kato Road, Fremont CA, 94538 • 510-668-7017 • www.exar.com SP3494_100_071012
PIN FUNCTION
Pin 1 - RO - Receiver output
Pin 2 - RE - Receiver Output Enable Active LOW
Pin 3 - DE - Driver Output Enable Active HIGH
Pin 4 - DI - Driver Input
Pin 5 - GND - Ground Connection
Pin 6 - A - Non-Inverting Driver Output/Receiver Input
Pin 7 - B - Inverting Driver Output/Receiver Input
Pin 8 - Vcc - Positive Supply +3.3V +/-5%
Pin Function SP3494
ELECTRICAL CHARACTERISTICS
TAMB = TMIN to TMAX and VCC = +3.3V +/-5% unless otherwise noted.
PARAMETERS MIN. TYP. MAX. UNITS CONDITIONS
SP3494 SHUTDOWN TIMING
Time to Shutdown 50 75 200 ns RE = 3.3V, DE =0V
Driver Enable from Shutdown
to Output High
65 150 ns Figures 4 and 11
Driver Enable from Shutdown
to Output Low
65 150 ns Figures 5 and 11
Receivers Enabled from
Shutdown to Output High
50 200 ns Figures 7 and 13,
S2 closed, S1 open
Receivers Enabled from
Shutdown to Output Low
50 200 ns Figures 7 and 13,
S1 closed, S2 open
POWER REQUIREMENTS
Supply Current , No Load 1000 2000 µA RE, DI = 0V or VCC ; DE = VCC
Supply Current , No Load 800 1500 µA RE = 0V, DI = 0V or VCC, DE = 0V
Shutdown Mode 10 µA DE = 0V, RE = VCC
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Exar Corporation 48720 Kato Road, Fremont CA, 94538 • 510-668-7017 • www.exar.com SP3494_100_071012
TEST CIRCUITS
R
RV
OC
D
Vcc
V
OD
Figure 1. Driver DC Test Load Circuit
GENERATOR
(NOTE 1) 50Ω
C
L
OUT
D
V
CC
R
L
=
60Ω
C
L
= 15pF (NOTE 2)
Figure 3. Driver Differential Output Delay and
Transition Time Circuit.
GENERATOR
(NOTE 1) 50Ω
S1
R
L
= 110Ω
OUT
C
L
= 50pF
(NOTE 2)
V
OM
= ≈ 1.5V
V
OH
+ V
OL
2
D
Figure 4. Driver Enable and Disable Timing Circuit,
Output High
Figure 2. Driver 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
Figure 5. Driver Enable and Disable Timing Circuit,
Output Low
GENERATOR
(NOTE 1) 50Ω
S1
RL = 110Ω
OUT
CL = 50pF
(NOTE 2)
D
0V OR 3V
VCC
GENERATOR
(NOTE 1)
50Ω
1.5V
0V
V
ID
ROUT
C
L
= 15pF
(NOTE 2)
V
OM
= V
CC
2
Figure 6. Receiver Propagation Delay Test Circuit
1.5V
-1.5V
S3
VID
GENERATOR
(NOTE 1)
50Ω
CL
= 15pF
(NOTE 2)
R
1k
S1
S2
VCC
A/Y
D
DI = 0 or Vcc
B/Z
DE = 0 or Vcc
I
OS D
100Ω
-7V to +12V V
Figure 7. Receiver Enable and Disable Timing
Circuit
Figure 8. Driver Short Circuit Current Limit Test
NOTE 1: The input pulse is supplied by a generator with the following characteristics:
PRR = 250kHz, 50% duty cycle, tR < 6.0ns, ZO = 50Ω.
NOTE 2: CL includes probe and stray capacitance.
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Exar Corporation 48720 Kato Road, Fremont CA, 94538 • 510-668-7017 • www.exar.com SP3494_100_071012
Figure 9. Driver Propagation Delay Waveforms
0V
V
OH
t
PLH
t
PHL
VOM
t
PHL
t
PLH
3V
V
OL
V
OH
1.5V 1.5V
INPUT
Y OUTPUT
VOM
Z OUTPUT
V
OL
VOM
VOM
VOM = VOH + VOL
2≈ 1.5V
SWITCHING WAVEFORMS
Figure 13. Receiver Enable and Disable Waveforms
IN 1.5V
tDO1
1.5V
tDO2
3V
0V
OUT
50% 50%
10% 10%
90% 90%
tTD tTD
2.0V
-2.0V
Figure 10. Driver Differential Output Delay and
Transition Time Waveforms
0V
VOH
tPZH
0.25V
tPHZ
V
OM
tPZL tPLZ
3V
VOL
VCC
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
VOM = VCC
2
Figure 12. Receiver Propagation Delay WaveformsFigure 11. Driver Enable and Disable Timing
Waveforms
3V
0V
t
PRHZ
1.5V
t
PRZH
t
PRSH
1.5V
1.5V
10%
0V
V
OH
RE
OUTPUT
S1 is open
S2 is closed
S3 = 1.5V
3V
0V
t
PRLZ
1.5V
t
PRZL
t
PRSL
1.5V
1.5V
10%
V
CC
RE
OUTPUT
S1 is closed
S2 is open
S3 = -1.5V
V
OL
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Exar Corporation 48720 Kato Road, Fremont CA, 94538 • 510-668-7017 • www.exar.com SP3494_100_071012
The SP3494 is a +3.3V low power half-
duplex transceiver that meets the electrical
specications of the RS-485 and RS-422
serial protocols. This device is pin-to-pin
compatible with the Exar SP3481 and
SP481 devices as well as popular industry
standards such as the MAX3486 and the
75176. The SP3494 feature Exar's BiCMOS
process allowing low power operation without
sacricing performance. The SP3494 has a
partially slew rate limited driver with a data
transmission rate of 2.5Mbps.
Driver
The driver outputs of the SP3494 are dif-
ferential 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 driver can maintain
greater than 1.5V voltage levels.
The SP3494 driver has an enable control
line which is active HIGH. A logic HIGH on
DE (pin 3) will enable the differential driver
outputs. A logic LOW on the DE (pin 3) will
force the driver outputs to high impedance
(high-Z).
The SP3494 driver will operate up to
2.5Mbps. In addition to adhering to the
250mA ISC maximum limit on the driver out-
put, the driver output short-circuit protection
will allow the device to withstand an innite
short circuit over the -7.0V to +12V common
mode range without damage.
Receiver
The receiver has differential inputs with an
input sensitivity of ±200mV. Input imped-
ance of the receiver is typically 15kΩ (12kΩ
minimum). A wide common mode range of
-7V to +12V allows for large ground potential
differences between systems. The receiver
is equipped with a fail-safe feature which
guarantees that the receiver output will be
in a high state when the input is left uncon-
nected. The receiver of the SP3494 operate
up to 2.5Mbps.
The receiver of the SP3494 has an enable
control line which is active LOW. A logic LOW
on RE (pin 2) of the SP3494 will enable the
differential receiver. A logic HIGH on RE
(pin 2) will disable the receiver.
The SP3494 is equipped with a shutdown
mode. To enable the shutdown state, both
the driver and receiver must be disable
simultaneously. A logic LOW on DE (pin 3)
and a logic HIGH on RE (pin 2) will put the
SP3494 into shutdown. In shutdown, the
supply current will drop to less than 10µA.
DESCRIPTION
INPUTS OUTPUTS
RE DE DI
LINE
CONDITION B A
X 1 1 No Fault 0 1
X 1 0 No Fault 1 0
X 0 X X Z Z
INPUTS OUTPUTS
RE DE A - B R
0 0 +0.2V 1
0 0 -0.2V 0
0 0 Inputs Open 1
1 0 X Z
Table 1. Transmit Function Truth Table
Table 2. Receive Function Truth Table
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Exar Corporation 48720 Kato Road, Fremont CA, 94538 • 510-668-7017 • www.exar.com SP3494_100_071012
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Exar Corporation 48720 Kato Road, Fremont CA, 94538 • 510-668-7017 • www.exar.com SP3494_100_071012
ORDERING INFORMATION
Model Temperature Range Package Types
SP3494CN-L ....................................................................... 0°C to +70°C ................................................................................................8-pin NSOIC
SP3494CN-L/TR ................................................................. 0°C to +70°C ................................................................................................8-pin NSOIC
SP3494EN-L...................................................................... -40°C to +85°C..............................................................................................8-pin NSOIC
SP3494EN-L/TR................................................................ -40°C to +85°C..............................................................................................8-pin NSOIC
REVISION HISTORY
DATE REVISION DESCRIPTION
10/15/02 -- Legacy Sipex Datasheet
07/10/12 1.0.0 Convert to Exar Format. Update ordering information and add new Figure 8 - Driver
Short Circuit Current Limit Test Circuit. Remove EOL device SP3493.
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 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 EXAR Corporation is adequately protected under the circumstances.
Copyright 2012 EXAR Corporation
Datasheet July 2012
For technical support please email Exar's Serial Technical Support group at: serialtechsupport@exar.com
Reproduction, in part or whole, without the prior written consent of EXAR Corporation is prohibited.
Note: /TR = Tape and Reel, -L = RoHS Packaging
