5 V, ±15 kV ESD Protected

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

ADM485E/ADM487E/ADM1487E

Rev. 0

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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

Data rates

ADM487E: 250 kbps

ADM485E/ADM1487E: 2.5 Mbps

Half-duplex options

Reduced slew rates for low EMI

−7 V to +12 V common-mode input range

Thermal shutdown and short-circuit protection

8-lead SOIC packages

APPLICATIONS

Energy/power metering

Lighting systems

Industrial control

Telecommunications

Security systems

Instrumentation

FUNCTIONAL BLOCK DIAGRAM

B

A

R

D

RO

RE

DE

DI

GND

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 Indus-

tries 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