The SN75177B and SN75178B differential bus repeaters are monolithic integrated devices each designed for one-way data communication on multipoint bus transmission lines. These devices are designed for balanced transmission bus line applications and meet EIA Standard RS-422-A and RS-485 and CCITT Recommendations V.11 and X.27. Each device is designed to improve the performance of the data communication over long bus lines. The SN75177B and SN75178B are identical except for the complementary enable 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 receiver and driver. The receiver features high input impedance, input hysteresis for increased noise immunity, and input sensitivity of ±200 mV over a common-mode input voltage range of -7 V to 12 V. The driver features thermal shutdown for protection from line fault conditions. Thermal shutdown is designed to occur at a junction temperature 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 buses employing the SN75172 and SN75174 differential line drivers, SN75173 and SN75175 differential line receivers, or SN75176B bus transceiver.

• Meets EIA Standards RS-422-A and RS-485 and CCITT Recommendations V.11 and X.27
• Designed for Multipoint Transmission on Long Bus Lines in Noisy Environments
• 3-State Outputs
• Bus Voltage Range . . . -7 V to 12 V
• Positive and Negative Current Limiting
• Driver Output Capability . . . 60 mA Max
• Driver Thermal Shutdown Protection
• Receiver Input Impedance . . . 12 k Min
• Receiver Input Sensitivity . . . ±200 mV
• Receiver Input Hysteresis . . . 50 mV Typ
• Operates From Single 5-V Supply
• Low Power Requirements