SN65HVD21D

The SN65HVD21D from Texas Instruments is an active RS-485 transceiver designed for robust performance in demanding environments. It supports half-duplex communication with a signaling rate of up to 5Mbps.

This transceiver operates over an extended common-mode voltage range of -20V to 25V, exceeding standard TIA/EIA-485 requirements. Key features include fault protection from -27V to 27V, receiver equalization for extended cable lengths, and a reduced unit load allowing for up to 256 nodes on the bus. It also offers failsafe receiver operation for open-circuit, short-circuit, and idle-bus conditions.

Packaged in an 8-pin SOIC, the SN65HVD21D is suitable for surface mounting. It operates within an industrial temperature range of -40°C to 85°C and requires a supply voltage between 4.5V and 5.5V. The device exhibits low standby supply current of 1µA and has 130mV of receiver hysteresis.

Example applications include digital motor controllers, remote sensors and terminals, industrial process control, security stations, and environmental control systems. Its design is optimized for long-cable networks and harsh environments where ordinary transceivers may not suffice.