Full-Duplex, Low Power,

Slew Rate Limited, EIA RS-485 Transceivers

ADM488/ADM489

Rev. D

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FEATURES

Meets EIA RS-485 and RS-422 standards

250 kbps data rate

Single 5 V ± 10% supply

−7 V to +12 V bus common-mode range

12 kΩ 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 μA supply current

APPLICATIONS

Low power RS-485 and RS-422 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

transceivers suitable for communication on multipoint bus

transmission lines. They are intended for balanced data

transmission and comply with both Electronics Industries

Association (EIA) RS-485 and RS-422 standards. Both products

contain 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 kΩ, allowing 32 transceivers to be

connected on the bus.

The ADM488/ADM489 operate from a single 5 V ± 10% power

supply. Excessive power dissipation caused by bus contention or

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.

FUNCTIONAL BLOCK DIAGRAMS

ADM488

R

D

RO

DI

A

B

Z

Y

Figure 1.

ADM489

R

D

RO

DI

A

B

Z

Y

DE

RE

Figure 2.

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

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

The ADM488/ADM489 are fabricated on BiCMOS, an

advanced mixed technology process combining low power

CMOS with fast switching bipolar technology.

The ADM488/ADM489 are fully specified over the industrial

temperature range and are available in PDIP, SOIC, and TSSOP

packages.