5 V, ±15 kV ESD Protected

Half-Duplex, RS-485/RS-422 Transceivers

ADM485E/ADM487E/ADM1487E

Rev. B

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FEATURES

TIA/EIA RS-485/RS-422 compliant

ESD protection on RS-485 I/O pins

±15 kV human body model (HBM)

Data rates

ADM487E: 250 kbps

ADM485E/ADM1487E: 2.5 Mbps

Half-duplex

Reduced slew rates for low EMI

Common-mode input range: −7 V to +12 V

Thermal shutdown and short-circuit protection

8-lead SOIC packages

ADM487EW qualified for automotive applications

APPLICATIONS

Energy/power metering

Lighting systems

Industrial control

Telecommunications

Security systems

Instrumentation

FUNCTIONAL BLOCK DIAGRAM

B

A

R

D

RO

RE

DE

DI

GND

VCC

ADM485E/

ADM487E/

ADM1487E

Figure 1.

GENERAL DESCRIPTION

The ADM485E/ADM487E/ADM1487E are 5 V, low power

data transceivers with ±15 kV ESD protection suitable for half-

duplex communication on multipoint bus transmission lines.

They are designed for balanced data transmission and comply

with Telecommunication Industry Association/Electronics

Industries Association (TIA/EIA) standards RS-485 and RS-422.

The ADM487E and ADM1487E have a 1/4 unit load receiver

input impedance that allows up to 128 transceivers on a bus,

whereas the ADM485E allows up to 32 transceivers on a bus.

Because only one driver is enabled at any time, the output of a

disabled or power-down driver is three-stated to avoid overloading

the bus.

The driver outputs are slew rate limited to reduce EMI and data

errors caused by reflections from improperly terminated buses.

Excessive power dissipation caused by bus contention or output

shorting is prevented with a thermal shutdown circuit.

The parts are fully specified over the industrial temperature

ranges and are available in 8-lead SOIC packages.

Table 1. Selection Table

Part

Number

Half-/Full-

Duplex

Guaranteed

Data Rate

(Mbps)

Slew Rate

Limited

Low Power

Shutdown

Driver/Receiver

Enable

Quiescent

Current (μA)

Number of

Nodes on Bus

Pin

Count

ADM485E

Half

2.5

No

No

Yes

300

32

8

ADM487E

Half

0.25

Yes

Yes

Yes

120

128

8

ADM1487E

Half

2.5

No

No

Yes

230

128

8