Date: 03-04-05

Programmable Dual RS-232/RS-485 Transceiver

© Copyright 2005 Sipex Corporation

1

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

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

ProgrammableDualRS-232/RS-485Transceiver

®

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 transceivers 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.

DESCRIPTION

SEL A

TTL/CMOS

TTL/CMOS

TTL/CMOS

0.1µF

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

0.1µF

0.1µF

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

18

RI4

RI3

RX3

RX4

15KΩ

15KΩ

15KΩ

15KΩ

400KΩ

Vcc

400KΩ

Vcc

SEL D

RS-485

RS-485

+5V

+5V

SP331

TYPICAL APPLICATION CIRCUITS

Now Available in Lead Free Packaging