STMicroelectronics' STR485LVQT is a low-power differential line transceiver for data transmission standard RS485 applications in half-duplex mode. Data and enable signals are compatible with 1V8 or 3V3 supplies. Bus signal supply is connected to 3.3 V ±10%. Each driver output and receiver input is protected against ±4 kV electrostatic discharge (HBM), ±8 kV contact discharge, and ±16 kV air discharge shocks without latch-up. Two speeds are selectable through SLR pin: fast data rate up to 20 Mbps or slow data rate for extended cable runs at 250 kbps. Excessive power dissipation caused by bus contention or faults is prevented by a thermal shutdown circuit that forces the driver outputs into a high impedance state. The receiver has a fail-safe feature which guarantees a high output state when the inputs are left open, shorted, or idle.