GENERAL DESCRIPTION

The ADM1486 is a differential line transceiver suitable for high speed bidirectional data communication on multipoint bus transmission lines. It is designed for balanced data transmission, complies with EIA Standards RS-485 and RS-422, and is recommended for PROFIBUS applications. The part contains a differential line driver and a differential line receiver. Both the driver and the receiver may be enabled independently. When disabled or powered down, the driver outputs are high impedance.

The ADM1486 operates from a single 5 V power supply. Excessive power dissipation caused by bus contention or output shorting is prevented by short-circuit protection and thermal circuitry. Short-circuit protection circuits limit the maximum output current to ±200 mA during fault conditions. A thermal shutdown circuit senses if the die temperature rises above 150°C and forces the driver outputs into a high impedance state under this condition.

Up to 50 transceivers may be connected simultaneously on a bus, but only one driver should be enabled at a time. Therefore, it is important that the remaining disabled drivers do not load the bus.

To ensure this, the ADM1486 driver features high output impedance when disabled and when powered down. This minimizes the loading effect when the transceiver is not being used. The high impedance driver output is maintained over the entire common-mode voltage range from ?7 V to +12 V.

The receiver contains a fail-safe feature that results in a logic high output state if the inputs are unconnected (floating).

FEATURES

Meets and exceeds EIA RS-485 and EIA RS-422 standards

30 Mbps data rate

Recommended for PROFIBUS applications

2.1 V minimum differential output with 54 ? termination

Low power 0.8 mA ICC

Thermal shutdown and short-circuit protection

0.5 ns skew driver and receiver

Driver propagation delay: 11 ns

Receiver propagation delay: 12 ns

High impedance outputs with drivers disabled or power off

Superior upgrade for SN65ALS1176

Available in standard 8-lead SOIC package

APPLICATIONS

Industrial field equipment