The ADM4850/ADM4851/ADM4852/ADM4853/ADM4854/ ADM4855/ADM4856/ADM4857 are differential line transceivers suitable for high speed， half-duplex 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 devices have a 1/8-unit load receiver input impedance， which allows up to 256 transceivers on one bus. Because only one driver must 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.