SP331
Programmable Dual RS-232/RS-485 Transceiver
Description
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 specifications. The RS-485 transceiv-
ers can operate up to 10Mbps while adhering to the RS-485
specifications. The SP331 includes a self-test loopback mode where
the driver outputs are internally configured 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.
Typical Applications Circuit
FEATURES
■■ +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
Ordering Information - Back Page
+5V
0.1µF
0.1µF
+5V
+5V
TTL/CMOS
TTL/CMOS
TTL/CMOS
TTL/CMOS
TTL/CMOS
TTL/CMOS
TTL/CMOS
TTL/CMOS
5
9 C1+
12 C1-
11 C2+
VCC
10
SP331
V+
V- 14
0.1µF
13 C2-
24
2
SEL A
SEL B
Vcc
400KΩ
26 TI1
27 TI2 Vcc
400KΩ
28 TI3
T1
T3
1 TI4
19 RX1
R1
20 RX2
0.1µF
23
SEL D
0V
TX2 7
TX1 6
TX4 3
TX3 4
RI2 16
15KΩ
RI1 15
15KΩ
RS-485
RS-485
RS-485
RS-485
RS-485
RS-485
21 RX3
22 RX4
8 GND
R3
RI4 18
15KΩ
RI3 17
15KΩ
25
SEL C
RS-485
RS-485
0V
REV 1.0.1
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