1

®

FN6074.3

ISL4489E, ISL4491E

Low Power, High Speed and Slew Rate

Limited, Full Duplex, RS-485/RS-422

Transceivers

The ISL4489E, ISL4491E are ESD protected, “fractional”

unit load, BiCMOS, 5V powered, single transceivers that

meet both the RS-485 and RS-422 standards for balanced

communication. Each driver output and receiver input is

protected against ±15kV ESD strikes, without latch-up.

Unlike competitive versions, these Intersil devices are

specified for 10% tolerance supplies (4.5V to 5.5V).

Rx inputs and Tx outputs present a “1/8 unit load” to the

RS-485 bus, which allows a total of 256 transmitters and

receivers on the network for large node count systems.

These devices are configured for full duplex (separate Rx

input and Tx output pins) applications, so they are ideal for

RS-422 networks requiring high ESD tolerance on the bus

pins.

The ISL4489E utilizes a slew rate limited driver which

reduces EMI, and minimizes reflections from improperly

terminated transmission lines, or unterminated stubs in

multidrop and multipoint applications.

Data rates up to 15Mbps are achievable by using the

ISL4491E, which features higher slew rates.

Receiver (Rx) inputs feature a “fail-safe if open” design,

which ensures a logic high Rx output if Rx inputs are floating.

Driver (Tx) outputs are short circuit protected, even for

voltages exceeding the power supply voltage. Additionally,

on-chip thermal shutdown circuitry disables the Tx outputs to

prevent damage if power dissipation becomes excessive.

Features

• Pb-free Available as an Option (RoHS Compliant)

(See Ordering Info)

- Class 3 ESD Level on all Other Pins . . . . . . >7kV HBM

• 1/8 Unit Load Allows up to 256 Devices on the Bus

• High Data Rates (ISL4491E) . . . . . . . . . . . up to 15Mbps

• Slew Rate Limited Version for Error Free Data

Transmission (ISL4489E)

• Very Low Quiescent Current:

• -7V to +12V Common Mode Input Voltage Range

• Three-State Rx and Tx Outputs

• Full Duplex Pinout

• Operates from a Single +5V Supply (10% Tolerance)

• Current Limiting and Thermal Shutdown for driver

Overload Protection

Applications

• Factory Automation

• Security Networks

• Building Environmental Control Systems

• Industrial/Process Control Networks

• Level Translators (e.g., RS-232 to RS-422)

• RS-232 “Extension Cords”

TABLE 1. SUMMARY OF FEATURES

PART

NUMBER

HALF/FULL

DUPLEX

HIGH ESD?

NO. OF DEVICES

ALLOWED ON BUS

DATA RATE

(Mbps)

SLEW-RATE

LIMITED?

RECEIVER/

DRIVER ENABLE?

QUIESCENT

PIN

COUNT

ISL4489E

Full

Yes

256

0.25

Yes

Yes

140

14

ISL4491E

Full

Yes

256

15

No

Yes

370

14

Data Sheet

April 28, 2006

CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.

1-888-INTERSIL or 321-724-7143

Copyright © Intersil Americas Inc. 2004, 2006. All Rights Reserved.

All other trademarks mentioned are the property of their respective owners.