RS-485/RS-422 full-duplex transceiver for 3.3 V industrial buses
5 Mbps data rate and 50 mV hysteresis — bus margin at speed
At 5 Mbps the SN65HVD31DG4 handles Profibus and similar industrial fieldbus rates without stretching the bit time. The 50 mV of built-in receiver hysteresis means the part rejects differential noise on unterminated or lightly terminated stubs better than a plain comparator front-end — useful when the cable run exceeds a few metres in an electrically noisy environment. The full-duplex architecture keeps separate transmit and receive pairs, so no direction-control GPIO is needed; the bus is always listening.
The supply range covers the common 3.3 V rail directly, so the transceiver's logic-level I/O mates with 3.3 V UARTs and MCUs without level shifters. Dropout margin at 3.0 V minimum accommodates a regulated rail that sags under load or through a long PCB trace. The single-supply scheme simplifies the BOM compared to a 5 V transceiver that would need an extra regulator or voltage translation.