1
Exar Corporation 48720 Kato Road, Fremont CA, 94538 • 510-668-7017 • www.exar.com SP331_100_012610
The SP331 is a programmable RS-232 and/or RS-485 transceiver IC. The SP331 contains
four drivers and four receivers when selected in RS-232 mode; and two drivers and two
receivers when selected in RS-485 mode. The SP331 also contains a dual mode which has
two RS-232 drivers/receivers plus one differential RS-485 driver/receiver.
The RS-232 transceivers can typically operate at 230kbps while adhering to the RS-232 speci-
cations. The RS-485 transceivers can operate up to 10Mbps while adhering to the RS-485
specications. The SP331 includes a self-test loopback mode where the driver outputs are
internally congured to the receiver inputs. This allows for easy diagnostic serial port testing
without using an external loopback plug. The RS-232 and RS-485 drivers can be disabled
(High-Z output) by controlling a set of four select pins.
DESCRIPTION
• +5V Only Operation
• Software Programmable RS-232 or RS-485
Selection
• Four RS-232 Transceivers in RS-232 Mode
• Two RS-485 Full-Duplex Transceivers in
RS-485 Mode
• Two RS-232 Transceivers and One RS-485
Transceiver in Dual Mode
• Self-Testing Loopback Mode
• Full Driver Tri-State (Hi-Z) Control
• Ideal for RS-232 to RS-485 conversion
SP331
Programmable Dual RS-232/RS-485 Transceiver
TI4
SEL_B
TX4
TX3
VCC
TX1
TX2
GND
C1+
V+ (VDD)
C2+
C1–
C2–
V– (VSS)
TI3
TI2
TI1
SEL_C
SEL_A
SEL_D
RX4
RX3
RX2
RX1
RI4
RI3
RI2
RI1
28
27
26
25
24
23
22
21
20
19
18
17
16
15
1
2
3
4
5
6
7
8
9
10
11
12
13
14
SP331
TYPICAL APPLICATIONS CIRCUIT
SEL A
TTL/CMOS
TTL/CMOS
TTL/CMOS
0.1µF
C1+
C1-
C2+
C2-
1
SEL B
2
+5V
VCC
5
GND
8
9
11
12
13
19
20
22
24
26
27
28
TTL/CMOS
TTL/CMOS
TTL/CMOS
TTL/CMOS
T1
T3
R1
RS-485
RS-485
RS-485
0V
V+
V-
0V
SEL C
RS-485
RS-485
RS-485
4
6
7
10
14
15
16
23
25
3
RI1
RI2
TX3
TX4
TX1
TX2
TI1
TI2
TI3
TI4
RX1
RX2
TTL/CMOS
21 R3
17
18RI4
RI3
RX3
RX4
15KΩ
400KΩ
Vcc
400KΩ
Vcc
SEL D
RS-485
RS-485
+5V
+5V
SP331
15KΩ
15KΩ
15KΩ
0.1µF
0.1µF
0.1µF
2
Exar Corporation 48720 Kato Road, Fremont CA, 94538 • 510-668-7017 • www.exar.com SP331_100_012610
SPECIFICATIONS
PARAMETER MIN. TYP. MAX. UNITS CONDITIONS
LOGIC INPUTS
VIL 0.8 Volts
VIH 2.0 Volts
LOGIC OUTPUTS
VOL 0.4 Volts IOUT = -3.2mA
VOH 2.4 Volts IOUT = 1.0mA
RS-232 DRIVER
DC Characteristics
HIGH Level Output +5.0 +15.0 Volts RL = 3kΩ, VIN = 0.8V
LOW Level Output -15.0 -5.0 Volts RL = 3kΩ, VIN = 2.0V
Open Circuit Voltage -15 +15 Volts
Short Circuit Current +/-100 mA VOUT = 0V
Power Off Impedance 300 ΩVCC = 0V, VOUT = +/-2.0V
AC Characteristics
Slew Rate 30 V/µs RL = 3kΩ, CL = 50pF; VCC = +5.0V,
TA @ 25°C
Transistion Time 1.5 µs RL = 3kΩ, CL = 2500pF; between
+/-3V, TA @ +25°C
Maximum Data Rate 120 235 kbps RL = 3kΩ, CL = 2500pF
Propagation Delay tPHL 2 8 µs Measured from 1.5V of VIN to 50%
of VOUT; RL = 3kΩ
Propagation Delay tPLH 2 8 µs
RS-232 RECEIVER
DC Characteristics
HIGH Threshold 1.7 3.0 Volts
LOW Threshold 0.8 1.2 Volts
Receiver Open Circuit Bias +2.0 Volts
Input Impedance 3 5 7 kΩ VIN = +15V to -15V
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......................+/-30V @ ≤100mA
Driver Outputs..................................................+/-15V
Maximum Data Rate..........................8Mbps (Note 1)
Storage Temperature.......................-65˚C to +150˚C
Power Dissipation
28-pin WSOIC...................................1000mW
Package Derating:
28-pin WSOIC
øJA................................................40 °C/W
Limits are specied at TA = 25°C and VCC = +5.0V unless otherwise noted.
3
Exar Corporation 48720 Kato Road, Fremont CA, 94538 • 510-668-7017 • www.exar.com SP331_100_012610
SPECIFICATIONS
PARAMETER MIN. TYP. MAX. UNITS CONDITIONS
RS-232 RECEIVER (continued)
AC Characteristics
Maximum Data Rate 120 235 kbps
Propagation Delay tPHL 0.25 1 µs Measured from 50% of VIN to 1.5V
of VOUT
Propagation Delay tPLH 0.25 1 µs
RS-485 DRIVER
DC Characteristics
Open Circuit Voltage 6.0 Volts
Differential Output 1.5 5.0 Volts RL = 54Ω, CL = 50pF
Balance +/-0.2 Volts |VT| - |VT|
Common-Mode Output 3.0 Volts
Output Current 28.0 mA RL = 54Ω
Short Circuit Current +/-250 mA Terminated in -7V to +10V
AC Characteristics
Maximum Data Rate 10 Mbps RL = 54Ω
Maximum Data Rate 8Mbps TA = +85°C, Note 1
Output Transition Time 30 50 ns Rise/Fall time, 10%-90%
Propagation Delay tPHL 80 120 ns See Figures 2 & 4, RDIFF = 54Ω,
CL1 = CL2 = 100pF
Propagation Delay tPLH 80 120 ns
Driver Output Skew 10 20 ns Per Figure 4, tSKEW = |tPHL - tPLH|
RS-485 RECEIVER
DC Characteristics
Common Mode Range -7.0 +12 Volts
Receiver Sensitivity +/-0.2 +/-0.3 Volts -7V ≤ VCM ≤ +12V
Input Impedance 12 15 kΩ -7V ≤ VCM ≤ +12V
AC Characteristics
Maximum Data Rate 10 Mbps
Maximum Data Rate 8Mbps TA = +85°C, Note 1
Propagation Delay tPHL 130 200 ns See Figures 2 & 6, RDIFF = 54Ω,
CL1 = CL2 = 100pF
Propagation Delay tPLH 130 200 ns
Differential Receiver Skew 10 20 ns tSKEW = |tPHL - tPLH|, RDIFF = 54Ω,
CL1 = CL2 = 100pF
ENABLE TIMING
RS-485 DRIVER
Enable Time (see Figures 3 and 5)
Enable to LOW 90 150 ns CL = 15pF, S1 Closed
Enable to HIGH 90 150 ns CL = 15pF, S2 Closed
Disable Time (see Figures 3 and 5)
Disable from LOW 80 120 ns CL = 15pF, S1 Closed
Disable from HIGH 80 120 ns CL = 15pF, S2 Closed
Limits are specied at TA = 25°C and VCC = +5.0V unless otherwise noted.
4
Exar Corporation 48720 Kato Road, Fremont CA, 94538 • 510-668-7017 • www.exar.com SP331_100_012610
SPECIFICATIONS
PARAMETER MIN. TYP. MAX. UNITS CONDITIONS
POWER REQUIREMENTS
Supply Voltage VCC +4.75 +5.25 Volts
Supply Current ICC
No Load (TX Disabled) 10 15 mA SEL_A ► SEL_D = "0001"
No Load (RS-232 Mode) 15 30 mA SEL_A ► SEL_D = "0000"
No Load (RS-485 Mode) 7 20 mA SEL_A ► SEL_D = "1100"
ENVIRONMENTAL
Operating Temperature
Commercial (_C_) 0 70 ºC
Industrial (_E_) -40 +85 ºC
Storage Temperature -65 +150 ºC
RECEIVER INPUT GRAPH
RS-485 RECEIVER
+1.0mA
-0.6mA
+6V +12V
-3V-7V
Maximum Input Current
Versus Voltage
1 Unit Load
TEST CIRCUITS
A
B
R
R
V
OD
V
OC
Figure 1. Driver DC Test Load Circuit
CL1
15pF
RO
A
B
A
B
DI
CL2
RL
Figure 2. Driver/Receiver Timing Test Circuit
500Ω
CL
Output
Under
Test
S1
S2
VCC
Figure 3. Driver Timing Test Load #2 Circuit
Limits are specied at TA = 25°C and VCC = +5.0V unless otherwise noted.
Note 1: Exceeding the maximum data rate of 8Mbps at TA = 85°C may permanently damage the device
5
Exar Corporation 48720 Kato Road, Fremont CA, 94538 • 510-668-7017 • www.exar.com SP331_100_012610
Figure 4. Driver Propagation Delays
Figure 5. Driver Enable and Disable Times
Figure 6. Receiver Propagation Delays
+3V
0V
DRIVER INPUT
A
B
DRIVER
OUTPUT
V
O
+
DIFFERENTIAL
OUTPUT
V
A
– V
B
0V
V
O
–
1.5V 1.5V
t
PLH
t
F
t
R
f ≥ 1MHz; t
R
≤ 10ns; t
F
≤ 10ns
V
O
1/2V
O
1/2V
O
t
PHL
t
SKEW
= |t
DPLH
- t
DPHL
|
t
DPLH
t
DPHL
+3V
0V
DE
5V
VOL
, B
0V
1.5V 1.5V
tZL
tZH
f = 1MHz; tR
< 10ns; tF < 10ns
VOH
, B 2.3V
2.3V
tLZ
tHZ
0.5V
0.5V
Output normally LOW
Output normally HIGH
VOH
VOL
RECEIVER OUT 1.5V 1.5V
tPHL
f = 1MHz; tR 10ns ; tF
≤ 10ns
OUTPUT
VOD2+
VOD2–
A – B 0V 0V
tPLH
INPUT
≤
SWITCHING WAVEFORMS
6
Exar Corporation 48720 Kato Road, Fremont CA, 94538 • 510-668-7017 • www.exar.com SP331_100_012610
Figure 7. Typical RS-232 Driver Output Figure 8. Typical RS-485 Driver Output
TTL
INPUT
DRIVER
OUTPUT
TTL
Input
Driver Output A
Driver Output B
Differential
Output
VA - VB
Figure 9. SP331 Pinout
TI4
SEL_B
TX4
TX3
VCC
TX1
TX2
GND
C1+
V+ (VDD)
C2+
C1–
C2–
V– (VSS)
TI3
TI2
TI1
SEL_C
SEL_A
SEL_D
RX4
RX3
RX2
RX1
RI4
RI3
RI2
RI1
28
27
26
25
24
23
22
21
20
19
18
17
16
15
1
2
3
4
5
6
7
8
9
10
11
12
13
14
SP331
7
Exar Corporation 48720 Kato Road, Fremont CA, 94538 • 510-668-7017 • www.exar.com SP331_100_012610
SEL A
TTL/CMOS
TTL/CMOS
TTL/CMOS
C1+
C1-
C2+
C2-
1
SEL B
2
+5V
VCC
5
GND
8
9
11
12
13
19
20
22
24
26
27
28
TTL/CMOS
TTL/CMOS
TTL/CMOS
TTL/CMOS
T1
T3
R1
RS-485
RS-485
RS-485
0V
V+
V-
0V
SEL C
RS-485
RS-485
RS-485
4
6
7
10
14
15
16
23
25
3
RI1
RI2
TX3
TX4
TX1
TX2
TI1
TI2
TI3
TI4
RX1
RX2
TTL/CMOS
21 R3
17
18RI4
RI3
RX3
RX4 15KΩ
400KΩ
Vcc
400KΩ
Vcc
SEL D
RS-485
RS-485
+5V
+5V
+5V
GND
TTL/CMOS
TTL/CMOS
TTL/CMOS
TTL/CMOS
0V
0.1µF
VCC
V+
V-
0V
SEL C
RS-232
TTL/CMOS
TTL/CMOS
TTL/CMOS
TTL/CMOS
T1
T2
T3
T4
TX1
TX2
TX3
TX4
TI1
TI2
TI3
TI4
RI1
RI2
RI3
RI4
RX1
RX2
RX3
RX4
13
4
5
6
7
8
10
C1+
C1-
C2+
C2-
9
11
12
13
14
15
16
17
18
19
20
21
22
23
SEL B
2
SEL A
24
25
26
27
28
R1
R2
R3
R4
5KΩ
400KΩ
Vcc
Vcc
Vcc
Vcc
RS-232
RS-232
RS-232
RS-232
RS-232
RS-232
RS-232
SEL D
0V
0V
SP331 SP331
0.1µF
0.1µF
0.1µF
400KΩ
400KΩ
400KΩ
5KΩ
5KΩ
5KΩ
0.1µF
0.1µF 0.1µF
0.1µF
15KΩ
15KΩ
15KΩ
Figure 10. Typical Operating Circuit
8
Exar Corporation 48720 Kato Road, Fremont CA, 94538 • 510-668-7017 • www.exar.com SP331_100_012610
FUNCTION TABLE FOR SELECT PINS
A B C D MODE FUNCTION
0 0 0 0 RS-232 All four RS-232 drivers active
0 0 0 1 RS-232 All four RS-232 drivers tri-state
0 0 1 0 RS-232 All four RS-232 drivers tri-state
0 0 1 1 RS-232 RS-232 (4ch) Loopback
0 1 0 0 RS-232/RS-485 T1 and T2 active RS-232; T3 tri-state RS-485
0 1 0 1 RS-232/RS-485 T1 and T2 tri-state RS-232; T3 active RS-485
0 1 1 0 RS-232/RS-485 T1 and T2 active RS-232; T3 tri-state RS-485
0 1 1 1 RS-232/RS-485 RS-232 (2ch) / RS-485 (1ch) Loopback
1 0 0 0 RS-485/RS-232 T1 active RS-485; T3 and T4 active RS-232
1 0 0 1 RS-485/RS-232 T1 tr-state RS-485; T3 active RS-232; T4 active RS232
1 0 1 0 RS-485/RS-232 All RS-485 and RS-232 drivers tri-state
1 0 1 1 RS-485/RS-232 RS-485 (1ch) / RS-232 (2ch) Loopback
1 1 0 0 RS-485 T1 and T3 active RS-485
1 1 0 1 RS-485 T1 tri-state RS-485; T3 active RS-485
1 1 1 0 RS-485 T1 active RS-485; T3 tri-state RS-485
1 1 1 1 RS-485 RS-485 (2ch) Loopback
Table 1. Mode Function Table. (Refer to Control Logic Conrmations for Block Diagrams)
THEORY OF OPERATION
The SP331 is made up of four separate
circuit blocks — the charge pump, drivers,
receivers, and decoder. Each of these circuit
blocks is described in more detail below.
Charge–Pump
The charge pump is a Exar–patented design
(U.S. 5,306,954) and uses a unique approach
compared to older less efcient designs.
The charge pump still requires four external
capacitors, but uses a four–phase voltage
shifting technique to attain symmetrical 10V
power supplies. Figure 15(a) shows the
waveform found on the positive side of capci-
tor C2, and Figure 15(b) shows the negative
side of capcitor C2. There is a free–running
oscillator that controls the four phases of
the voltage shifting. A description of each
phase follows.
Phase 1
— VSS charge storage —During this phase of
the clock cycle, the positive side of capaci-
tors C1 and C2 are initially charged to +5V.
Cl
+ is then switched to ground and charge
transferred to C2
–. Since C2
+ is connected to
+5V, the voltage potential across capacitor
C2 is now 10V.
Phase 2
— VSS transfer — Phase two of the clock con-
nects the negative terminal of C2 to the VSS
storage capacitor and the positive terminal
of C2 to ground, and transfers the generated
–l0V to C3. Simultaneously, the positive side
of capacitor C 1 is switched to +5V and the
negative side is connected to ground.
Phase 3
— VDD charge storage — The third phase
of the clock is identical to the rst phase
— the charge transferred in C1 produces
–5V in the negative terminal of C1, which
is applied to the negative side of capacitor
C2. Since C2
+ is at +5V, the voltage potential
across C2 is l0V.
Phase 4
— VDD transfer — The fourth phase of the
clock connects the negative terminal of C2
9
Exar Corporation 48720 Kato Road, Fremont CA, 94538 • 510-668-7017 • www.exar.com SP331_100_012610
to ground and transfers the generated l0V
across C2 to C4, the VDD storage capacitor.
Again, simultaneously with this, the positive
side of capacitor C1 is switched to +5V and
the negative side is connected to ground,
and the cycle begins again.
Since both V+ and V– are separately gen-
erated from VCC in a no–load condition, V+
and V– will be symmetrical. Older charge
pump approaches that generate V– from
V+ will show a decrease in the magnitude
of V– compared to V+ due to the inherent
inefciencies in the design.
The clock rate for the charge pump typically
operates at 15kHz. The external capaci-
tors must be 0.1µF with a 16V breakdown
rating.
External Power Supplies
For applications that do not require +5V only,
external supplies can be applied at the V+
and V– pins. The value of the external sup-
ply voltages must be no greater than ±l0V.
The current drain for the ±10V supplies is
used for RS-232. For the RS-232 driver the
current requirement will be 3.5mA per driver.
The external power supplies should provide
a power supply sequence of :+l0V, then +5V,
followed by –l0V.
V
CC
= +5V
–5V –5V
+5V
V
SS
Storage Capacitor
V
DD
Storage Capacitor
C
1
C
2
C
3
C
4
+
+
+ +
–
–
––
VCC = +5V
–10V
VSS Storage Capacitor
VDD Storage Capacitor
C1C2
C3
C4
+
+
+ +
–
–
––
V
CC
= +5V
–5V
+5V
–5V
V
SS
Storage Capacitor
V
DD
Storage Capacitor
C
1
C
2
C
3
C
4
+
+
+ +
–
–
––
V
CC
= +5V
+10V
V
SS
Storage Capacitor
V
DD
Storage Capacitor
C
1
C
2
C
3
C
4
+
+
+ +
–
–
––
Figure 11. Charge Pump Phase 1.
Figure 12. Charge Pump Phase 2.
Figure 13. Charge Pump Phase 3.
Figure 14. Charge Pump Phase 4.
+10V
GND
GND
-10V
a) C2+
b) C2-
Figure 15. Charge Pump Waveforms
10
Exar Corporation 48720 Kato Road, Fremont CA, 94538 • 510-668-7017 • www.exar.com SP331_100_012610
Drivers
The SP331 has four independent RS-232
single-ended drivers and two differential
RS-485 drivers. Control for the mode selec-
tion is done via a four–bit control word. The
drivers are pre-arranged such that for each
mode of operation the relative position and
functionality of the drivers are set up to ac-
commodate the selected interface mode. As
the mode of the drivers is changed, the elec-
trical characteristics will change to support
the requirements of clock, data, and control
line signal levels. Unused driver inputs can
be left oating; however, to ensure a desired
state with no input signal, pull–up resistors
to +5V or pull–down resistors to ground are
suggested. Since the driver inputs are both
TTL or CMOS compatible, any value resistor
less than 100kΩ will sufce.
When in RS-232 mode, the single-ended
RS-232 drivers produce compliant RS-232E
and ITU V.28 signals. Each of the four driv-
ers output single-ended bipolar signals in
access of ±5V with a full load of 3kΩ and
2500pF applied as specied. These drivers
can also operate at least 120kbps.
When programmed to RS-485 mode, the
differential RS-485 drivers produce complaint
RS-485 signals. Each RS-485 driver outputs
a unipolar signal on each output pin with a
magnitude of at least 1.5V while loaded with
a worst case of 54Ω between the driver's
two output pins. The signal levels and drive
capability of the RS-485 drivers allow the
drivers to also comply with RS-422 levels.
The transmission rate for the differential
drivers is 10Mbps.
Receivers
The SP331 has four single-ended receivers
when programmed for RS-232 mode and two
differential receivers when programmed for
RS-485 mode.
Control for the mode selection is done via a
4–bit control word, as in the drivers. As the
operating mode of the receivers is changed,
the electrical characteristics will change to
support the requirements of the appropriate
serial standard. Unused receiver inputs can
be left oating without causing oscillation. To
ensure a desired state of the receiver
output, a pull–up resistor of 100kΩ to +5V
should be connected to the inverting input
for a logic low, or the non–inverting input
for a logic high. For single-ended receiv-
ers, a pull–down resistor to ground of 5kΩ
is internally connected, which will ensure a
logic high output.
The RS-232 receiver has a single–ended
input with a threshold of 0.8V to 2.4V. The
RS-232 receiver has an operating voltage
range of ±15V and can receive signals up
to 120kbps. RS-232 receivers are used in
RS-232 mode for all signal types include
data, clock, and control lines of the RS-232
serial port.
The differential RS-485 receiver has an input
impedance of 15kΩ and a differential thresh-
old of ±200mV. Since the characteristics of
an RS-422 receiver are actually subsets of
RS-485, the receivers for RS-422 require-
ments are identical to the RS-485 receivers.
All of the differential receivers can receive
data up to 10Mbps.
Select Mode Pins
Similar to our SP500 family of multiprotocol
products, the SP331 has the ability to change
the conguration of the drivers and receiv-
ers via a 4–bit switch. Referring to Table 1;
RS-232 mode, RS-485 mode, or two differ-
ent combinations of RS-232/RS-485 can be
congured using the SEL_A and SEL_B pins.
The drivers can be put into tri-state mode
by using the SEL_C and SEL_D pins. All
receivers remain active during any tri-state
condition of the drivers.
Loopback Mode
Loopback is invoked by asserting "xx11"
into the select pins. In RS-232/RS-485 or
RS-485/RS-232 loopback mode, the RS-232
driver outputs loop back into the RS-232
receiver inputs and the RS-485 differential
driver loops back into the RS-485 receiver.
During loopback, the driver outputs and
receiver inputs are disconnected from the
outside world. The driver outputs are in tri-
state and the receiver inputs are disabled.
The input impedance of the receivers
during loopback is approximately 15kΩ to
ground.
11
Exar Corporation 48720 Kato Road, Fremont CA, 94538 • 510-668-7017 • www.exar.com SP331_100_012610
SEL A000000111111
SEL B 0 0 0 1 1 1 0 0 0 1 1 1
SEL C 0 0 1 0 0 1 0 0 1 0 0 1
SEL D 0 1 0 0 1 0 0 1 0 0 1 0
SP331 CONTROL LOGIC CONFIGURATION (Refer to Table 1)
SP331 LOOPBACK (Refer to Table 1)
28 T3 3
6
7
4
TX4
TX3
TX1
TX2
TI3
19 R1 16
15RI1
RI2
RX1
T1
26 TI1
21 R3 18
17RI3
RI4
RX3
28 T3
3
6
7
4
TX4
TX3
TX1
TX2
TI3
19 R1 16
15RI1
RI2
RX1
T1
R3
RX3
21
26 TI1
17RI3
T4
TI41
R4
RX4
22 18RI4
26 T1
7
4
3
6
TX2
TX1
TX3
TX4
TI1
21 R3 18
17RI3
RI4
RX3
T3
R1
RX1
19
28 TI3
15RI1
T2
TI227
R2
RX2
20 16RI2
26 T1
7
6
TX2
TX1
TI1
R1
RX1
19 15RI1
T2
TI227
R2
RX2
20 16RI2
4TX3
T3
TI328
3TX4
T4
TI41
R3
RX3
21 17RI3
R4
RX4
22 18RI4
SEL A 0 0 1 1
SEL B 0 1 0 1
SEL C 1 1 1 1
SEL D 1 1 1 1
26 T1
7
6
TX2
TX1
TI1
R1
RX1
19 15RI1
T2
TI227
R2
RX2
20 16RI2
4TX3
T3
TI328
3TX4
T4
TI41
R3
RX3
21 17RI3
R4
RX4
22 18RI4
26 T1
7
4
3
6
TX2
TX1
TX3
TX4
TI1
21 R3 18
17RI3
RI4
RX3
T3
R1
RX1
19
28 TI3
15RI1
T2
TI227
R2
RX2
20 16RI2
28 T3
3
6
7
4
TX4
TX3
TX1
TX2
TI3
19 R1 16
15RI1
RI2
RX1
T1
R3
RX3
21
26 TI1
17RI3
T4
TI41
R4
RX4
22 18RI4
28 T3 3
6
7
4
TX4
TX3
TX1
TX2
TI3
19 R1 16
15RI1
RI2
RX1
T1
26 TI1
21 R3 18
17RI3
RI4
RX3
12
Exar Corporation 48720 Kato Road, Fremont CA, 94538 • 510-668-7017 • www.exar.com SP331_100_012610
13
Exar Corporation 48720 Kato Road, Fremont CA, 94538 • 510-668-7017 • www.exar.com SP331_100_012610
ORDERING INFORMATION
Model Temperature Range Package Types
SP331CT-L .......................................................................... 0°C to +70°C .............................................................................................28-pin WSOIC
SP331CT-L/TR .................................................................... 0°C to +70°C .............................................................................................28-pin WSOIC
SP331ET-L....................................................................... -40°C to +85°C.............................................................................................28-pin WSOIC
SP331ET-L/TR................................................................. -40°C to +85°C.............................................................................................28-pin WSOIC
REVISION HISTORY
DATE REVISION DESCRIPTION
01-04-05 - Legacy Sipex Datasheet
01/26/10 1.0.0 Convert to Exar Format. Add Revision History table. Change revision to 1.0.0. Add
Note 1 and change maximum RS-485 data rate at +85C. Update ABS Max Rating
table.
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 2010 EXAR Corporation
Datasheet January 2010
Send your Interface technical inquiry with technical details to: uarttechsupport@exar.com
Reproduction, in part or whole, without the prior written consent of EXAR Corporation is prohibited.
Note: /TR = Tape and Reel