The SN75ALS171 and the SN75ALS171A triple differential bus transceivers are monolithic integrated circuits designed for bidirectional data communication on multipoint bus transmission lines. They are designed for balanced transmission lines, and each driver meets ANSI Standards EIA/TIA-422-B and RS-485 and both the drivers and receivers meet ITU Recommendation V.11. The SN75ALS171A is designed for FAST-20 SCSI and can transmit or receive data pulses as short as 30 ns with a maximum skew of 5 ns.

The SN75ALS171 and the SN75ALS171A operate from a single 5-V power supply. The drivers and receivers have individual active-high and active-low enables, respectively, which can be externally connected together to function as a direction control. The driver differential output and the receiver differential input pairs are connected internally to form differential input/output (I/O) bus ports that are designed to offer minimum loading to the bus when the driver is disabled or VCC is at 0 V. These ports feature wide positive and negative common-mode voltage ranges making the device suitable for party-line applications.

The SN75ALS171 and the SN75ALS171A are characterized for operation from 0°C to 70°C.

H = high level, L = low level, ? = indeterminate, X = irrelevant, Z = high impedance (off)

• Three Bidirectional Transceivers
• Driver Meets or Exceeds the Requirements of ANSI EIA/TIA-422-B and RS-485 and ITU Recommendation V.11
• Two Skew Limits Available
• Designed to Operate Up to 20 Million Data Transfers per Second (FAST-20 SCSI)
• High-Speed Advanced Low-Power Schottky Circuitry
• Low Pulse Skew...5 ns Max
• Designed for Multipoint Transmission on Long Bus Lines in Noisy Environments
• Features Independent Driver Enables and Combined Receiver Enables
• Wide Positive and Negative Input/Output Bus Voltages Ranges
• Driver Output Capacity...±60 mA
• Thermal Shutdown Protection
• Driver Positive- and Negative-Current Limiting
• Receiver Input Impedances...12 k Min
• Receiver Input Sensitivity...±300 mV Max
• Receiver Input Hysteresis...60 mV Typ
• Operates From a Single 5-V Supply
• Glitch-Free Power-Up and Power-Down Protection