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a

ADM488/ADM489

One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.

Tel: 617/329-4700

World Wide Web Site: http://www.analog.com

Fax: 617/326-8703

© Analog Devices, Inc., 1997

Full-Duplex, Low Power,

Slew Rate Limited, EIA RS-485 Transceivers

FUNCTIONAL BLOCK DIAGRAMS

FEATURES

Meets EIA RS-485 Standard

250 kbps Data Rate

Single +5 V

10% Supply

–7 V to +12 V Bus Common-Mode Range

12 k

Input Impedance

2 kV EFT Protection Meets IEC1000-4-4

High EM Immunity Meets IEC1000-4-3

Reduced Slew Rate for Low EM Interference

Short Circuit Protection

Excellent Noise Immunity

30

A Supply Current

APPLICATIONS

Low Power RS-485 Systems

DTE-DCE Interface

Packet Switching

Local Area Networks

Data Concentration

Data Multiplexers

Integrated Services Digital Network (ISDN)

GENERAL DESCRIPTION

The ADM488 and ADM489 are low power differential line

transceiver suitable for communication on multipoint bus trans-

mission lines.

They are intended for balanced data transmission and comply

with both EIA Standards RS-485 and RS-422. Both products

contains a single differential line driver and a single differential

line receiver making them suitable for full duplex data transfer.

The ADM489 contains an additional receiver and driver enable

control.

The input impedance is 12 k

Ω, allowing 32 transceivers to be

connected on the bus.

The ADM488/ADM489 operates from a single +5 V

± 10%

power supply. Excessive power dissipation caused by bus con-

tention or by output shorting is prevented by a thermal shut-

down circuit. This feature forces the driver output into a high

impedance state if during fault conditions a significant tempera-

ture increase is detected in the internal driver circuitry.

The receiver contains a fail-safe feature that results in a logic

high output state if the inputs are unconnected (floating).

The ADM488/ADM489 is fabricated on BiCMOS, an ad-

vanced mixed technology process combining low power CMOS

with fast switching bipolar technology.

The ADM488/ADM489 is fully specified over the industrial

temperature range and is available in DIP, SOIC and TSSOP

packages.

ADM488

R

D

RO

DI

A

B

Z

Y

ADM489

R

D

RO

DI

A

B

Z

Y

RE

DE