5V的ESD保护的半双工RS-485/RS-422收发器adm485e/adm487e/adm1487e

　　The ADM485E/ADM487E/ADM1487E are 5 V， low power data transceivers with ±15 kV ESD protection suitable for halfduplex communication on multipoint bus transmission lines. They are designed for balanced data transmission and comply with Telecommunication Industry Association/Electronics Industries Association （TIA/EIA） standards RS-485 and RS-422. The ADM487E and ADM1487E have a 1/4 unit load receiver input impedance that allows up to 128 transceivers on a bus， whereas the ADM485E allows up to 32 transceivers on a bus. Because only one driver is enabled at any time， the output of a disabled or power-down driver is three-stated to avoid overloading the bus. 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 output shorting is prevented with a thermal shutdown circuit. The parts are fully specified over the industrial temperature ranges and are available in 8-lead SOIC packages.