What this transceiver does on the bus
The SN75ALS171ADW is a half-duplex transceiver supporting both RS422 and RS485 protocols, with three independent driver and receiver pairs on one chip. It runs off a 5V nominal supply (4.75V to 5.25V) and includes 60 mV of receiver hysteresis to reject noise on long cable runs. The commercial temperature range (0°C to 70°C) suits indoor control panels, PLC interfaces, and building automation — not outdoor or under-hood environments.
Package and mounting for the rework bench
Housed in a 20-SOIC wide-body package (0.295" body width, 7.50 mm), surface-mount only — no socket option, so plan for soldering with a fine-tip iron or hot-air station. The 20-SOIC wide footprint is common enough that a stencil and reflow profile for standard lead-free solder will work; no exposed pad to worry about.
