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Exar Corporation 48720 Kato Road, Fremont CA, 94538 • 510-668-7017 • www.exar.com SP334_100_090909
The SP334 is a programmable RS-232 and/or RS-485 transceiver IC. The SP334 contains
three drivers and ve receivers when selected in RS-232 mode; and two drivers and two
receivers when selected in RS-485 mode.
The RS-232 transceivers can typically operate at 230kbps while adhering to
the RS-232 specifications. The RS-485 transceivers can operate up to 10Mbps
while adhering to the RS-485 specications. The RS-485 drivers can be disabled
(High-Z output) by the TXEN enable pin. The RS-232 and RS-485 receiver outputs can be
disabled by the RXEN pin.
DESCRIPTION
• +5V Single Supply Operation
• Software Programmable RS-232 or RS-485
Selection
• Three RS-232 Drivers and Five Receivers
in RS-232 Mode
• Two RS-485 Full-Duplex Transceivers in
RS-485 Mode
• Full Differential Driver Tri-State (Hi-Z) Control
• Receiver Output Tri-State Control
SP334
Programmable RS-232/RS-485 Transceiver
TYPICAL APPLICATIONS CIRCUIT
TTL/CMOS
TTL/CMOS
TTL/CMOS
0.1µF
C1+
C1-
C2+
C2-
2
+5V
VCC
5
GND
8
9
11
12
13
19
26
27
1
TTL/CMOS
T1
T3
R1
RS-485
RS-485
RS-485
V+
V-
+5V
RS232/ RS485
RS-485
RS-485
RS-485
4
6
7
10
14
16
15
25
3
RI2
RI1
TX3
TX4
TX1
TX2
TI1
TI3
RX1
TTL/CMOS
21
R3
17
18RI4
RI3
RX3
RXEN
15KΩ
400KΩ
Vcc
400KΩ
Vcc
RS-485
RS-485
SP334
15KΩ
15KΩ
15KΩ
0.1µF
0.1µF
0.1µF
TXEN
TTL/CMOS
TI3
TXEN(n/c)
TX4(n/c)
TX3
VCC
TX1
TX2
GND
C1+
V+
C2+
C1–
C2–
V–
TI2
TI1
RXEN
RS232/RS485
RI5
RX5
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
SP334
(in RS-232 Mode)
