Full-Duplex, Low Power,

Slew Rate Limited, EIA RS-485 Transceivers

ADM488A/ADM489A

Rev. 0

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FEATURES

Complies with ANSI TIA/EIA-485-A-1998 and

ISO 8482: 1987(E)

250 kbps data rate

Single 5 V ± 10% supply

−7 V to +12 V bus common-mode range

Connect up to 32 nodes on the bus

Reduced slew rate for low EM interference

Short-circuit protection

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 ADM488A and ADM489A 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 RS-485 and RS-422

standards of the Electronics Industries Association (EIA). Both

products contain a single differential line driver and a single

differential line receiver, making them suitable for full-duplex

data transfer. The ADM489A contains an additional receiver

and driver enable control.

The input impedance is 12 kΩ, allowing 32 transceivers to be

connected on the bus. The ADM488A/ADM489A operate from

a single 5 V ± 10% power supply.

FUNCTIONAL BLOCK DIAGRAMS

ADM488A

R

D

RO

DI

A

B

Z

Y

Figure 1. ADM488A

ADM489A

R

D

RO

DI

A

B

Z

Y

DE

RE

Figure 2. ADM489A

Excessive power dissipation that is 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.

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

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

The ADM488A/ADM489A are fabricated on BiCMOS, an

advanced mixed technology process combining low power

CMOS with fast switching bipolar technology.

The ADM488A/ADM489A are fully specified over the industrial

temperature range and are available in SOIC and MSOP packages.