SN75178B

The SN75177B and SN75178B differential bus repeaters are monolithic integrated devices each designed forone-way data communication on multipoint bus transmission lines. These devices are designed for balancedtransmission bus line applications and meet EIA Standard RS-422-A and RS-485 andCCITTRecommendations V.11 and X.27. Each device is designed to improve the performance of the datacommunication over long bus lines. The SN75177B and SN75178B are identical except for the complementaryenable inputs, which allow the devices to be used in pairs for bidirectional communication.

The SN75177B and SN75178B feature positive- and negative-current limiting 3-state outputs for the receiverand driver. The receiver features high input impedance, input hysteresis for increased noise immunity, and inputsensitivity of ±200 mV over a common-mode input voltage range of 7 V to 12 V.

The driver SN75178B features thermalshutdown for protection from line fault conditions. Thermal shutdown is designed to occur at a junctiontemperature of approximately 150°C. The driver is designed to drive current loads up to 60 mA maximum.

The SN75177B and SN75178B are designed for optimum performance when used on transmission busesemploying the SN75172 and SN75174 differential line drivers, SN75173 and SN75175 differential linereceivers, or SN75176B bus transceiver.