a

ADM3485E

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

Tel: 781/329-4700

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

Fax: 781/326-8703

© Analog Devices, Inc., 2000

REV. A

Information furnished by Analog Devices is believed to be accurate and

reliable. However, no responsibility is assumed by Analog Devices for its

use, nor for any infringements of patents or other rights of third parties

which may result from its use. No license is granted by implication or

otherwise under any patent or patent rights of Analog Devices.

ESD Protected, EMC Compliant, 3.3 V,

20 Mbps, EIA RS-485 Transceiver

FUNCTIONAL BLOCK DIAGRAM

ADM3485E

RO

RE

DE

DI

B

A

R

D

FEATURES

Operates with +3.3 V Supply

ESD Protection: 8 kV Meets IEC1000-4-2

EFT Protection: 2 kV Meets IEC1000-4-4

EIA RS-422 and RS-485 Compliant Over Full CM Range

19 k

Input Impedance

Up to 50 Transceivers on Bus

20 Mbps Data Rate

Short Circuit Protection

Specified Over Full Temperature Range

Thermal Shutdown

Interoperable with 5 V Logic

1 mA Supply Current

2 nA Shutdown Current

8 ns Skew

APPLICATIONS

Telecommunications

DTE-DCE Interface

Packet Switching

Local Area Networks

Data Concentration

Data Multiplexers

Integrated Services Digital Network (ISDN)

AppleTalk

Industrial Controls

GENERAL DESCRIPTION

The ADM3485E is a low power differential line transceiver

designed to operate using a single +3.3 V power supply. Low

power consumption makes it ideal for power sensitive applica-

tions. It is suitable for communication on multipoint bus trans-

mission lines. Internal protection against electrostatic discharge

(ESD) and electrical fast transient (EFT) allows operation in

electrically harsh environments.

It is intended for balanced data transmission and complies with

both EIA Standards RS-485 and RS-422. It contains a differen-

tial line driver and a differential line receiver, and is suitable for

half duplex data transfer.

The input impedance is 19 k

Ω allowing up to 50 transceivers to

be connected on the bus.

Excessive power dissipation caused by bus contention or by

output shorting is prevented by a thermal shutdown circuit.

This feature forces the driver output into a high impedance

state if, during fault conditions, a significant temperature

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 ADM3485E is fabricated on BiCMOS, an advanced

mixed technology process combining low power CMOS

with fast switching bipolar technology.

The ADM3485E is fully specified over the industrial tem-

perature range and is available in 8-lead DIP and SOIC

packages.