High Speed, ESD-Protected, Half-/Full-Duplex

i

Coupler Isolated RS-485 Transceiver

ADM2491E

Rev. B

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FEATURES

Isolated, RS-485/RS-422 transceiver, configurable as half- or

full-duplex

±8 kV ESD protection on RS-485 input/output pins

16 Mbps data rate

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

ISO 8482: 1987(E)

Suitable for 5 V or 3.3 V operation (V

High common-mode transient immunity: >25 kV/μs

Receiver has open-circuit, fail-safe design

32 nodes on the bus

Thermal shutdown protection

Safety and regulatory approvals

UL recognition: 5000 V rms isolation voltage

for 1 minute, per UL 1577

VDE certificate of conformity

DIN V VDE V 0884-10 (VDE V 0884-10): 2006-12

Reinforced insulation, V

Operating temperature range: −40°C to +85°C

Wide body, 16-lead SOIC package

APPLICATIONS

Isolated RS-485/RS-422 interfaces

Industrial field networks

INTERBUS

Multipoint data transmission systems

FUNCTIONAL BLOCK DIAGRAM

A

B

Y

Z

TxD

DE

RxD

ADM2491E

RE

Figure 1.

GENERAL DESCRIPTION

The ADM2491E is an isolated data transceiver with ±8 kV ESD

protection and is suitable for high speed, half- or full-duplex

communication on multipoint transmission lines. For half-

duplex operation, the transmitter outputs and the receiver

inputs share the same transmission line. Transmitter output

Pin Y is linked externally to receiver input Pin A, and transmit-

ter output Pin Z is linked to receiver input Pin B.

The ADM2491E is designed for balanced transmission lines

and complies with ANSI TIA/EIA RS-485-A-1998 and ISO

8482: 1987(E). The device employs Analog Devices, Inc.,

iCoupler® technology to combine a 3-channel isolator, a three-

state differential line driver, and a differential input receiver into

a single package.

The differential transmitter outputs and receiver inputs feature

electrostatic discharge circuitry that provides protection to

±8 kV using the human body model (HBM). The logic side of

the device can be powered with either a 5 V or a 3.3 V supply,

whereas the bus side requires an isolated 5 V supply.

The device has current-limiting and thermal shutdown features

to protect against output short circuits and situations in which

bus contention could cause excessive power dissipation.

The ADM2491E is available in a wide body, 16-lead SOIC package

and operates over the −40°C to +85°C temperature range.