GENERAL DESCRIPTION

The ADM4850/ADM4851/ADM4852/ADM4853/ADM4854/ADM4855/ADM4856/ADM4857 are differential line transceivers suitable for high speed half- and full-duplex data communication on multipoint bus transmission lines. They are designed for balanced data transmission and comply with EIA Standards RS-485 and RS-422. The ADM4850/ADM4851/ADM4852/ADM4853 are half duplex transceivers that share differential lines and have separate enable inputs for the driver and receiver. The full-duplex ADM4854/ADM4855/ADM4856/ADM4857 transceivers have dedicated differential line driver outputs and receiver inputs.

The parts have a 1/8-unit-load receiver input impedance, which allows up to 256 transceivers on one bus. Because only one driver should be enabled at any time, the output of a disabled or powered-down driver is three-stated to avoid overloading the bus.

The receiver inputs have a true fail-safe feature, which ensures a logic high output level when the inputs are open or shorted. This guarantees that the receiver outputs are in a known state before communication begins and when communication ends. 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 by output shorting is prevented with a thermal shutdown circuit.

The parts are fully specified over the commercial and industrial temperature ranges and are available in 8-lead SOIC, LFCSP (ADM4850/ADM4851/ADM4852/ADM4853), and MSOP (ADM4850 only) packages.

FEATURES

EIA RS-485-/RS-422-compliant

Data rate options

ADM4850/ADM4854: 115 kbps

ADM4851/ADM4855: 500 kbps

ADM4852/ADM4856: 2.5 Mbps

ADM4853/ADM4857: 10 Mbps

Half- and full-duplex options

Reduced slew rates for low EMI

True fail-safe receiver inputs

5 μA (maximum) supply current in shutdown mode

Up to 256 transceivers on one bus

Outputs high-Z when disabled or powered off

?7 V to +12 V bus common-mode range

Thermal shutdown and short-circuit protection

Pin-compatible with the MAX308x

Specified over the ?40°C to +85°C temperature range

Available in 8-lead SOIC, LFCSP, and MSOP packages

Qualified for automotive applications

APPLICATIONS

Low power RS-485 applications

EMI-sensitive systems

DTE-DCE interfaces

Industrial control

Packet switching

Local area networks

Level translators