ADM3491E: 3.3 V, ±15 kV ESD-Protected, Full-Duplex Transceiver Featuring Enable Inputs for the Driver & Receiver

The ADM3486E/ADM3490E/ADM3491E are 3.3 V low power data transceivers with ±15 kV ESD protection suitable for fulland half-duplex communication on multipoint bus transmission lines. They are designed for balanced data transmission and comply with TIA/EIA standards RS-485 and RS-422. The ADM3486E is a half-duplex transceiver that shares differential lines and has separate enable inputs for the driver and receiver. The full-duplex ADM3490E/ADM3491E transceivers have dedicated differential line driver outputs and receiver inputs. The ADM3491E also features enable inputs for the driver and receiver.

The devices have a 12 k receiver input impedance which allows up to 32 transceivers on a bus. Since 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 driver outputs of the ADM3486E are slew rate limited in order to reduce EMI and data errors caused by reflections from improperly terminated buses. The receiver has a failsafe feature which ensures a logic high output when the inputs are floating. 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 narrow 8-lead and 14- lead (ADM3491E) SOIC packages.

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