SN65HVD11D

The SN65HVD11D from Texas Instruments is a 3.3V-powered RS-485 half-duplex transceiver designed for multipoint bus communication. Its 1/4 unit load receiver input impedance allows up to 256 transceivers on a single bus, four times the standard 32-node limit. The slew-rate-limited driver operates at 250kbps, minimizing EMI and reflections on improperly terminated cables. With ±15kV HBM ESD protection and a wide -7V to +12V common-mode input range, the SN65HVD11D is robust enough for harsh industrial environments.

The SN65HVD11D converts single-ended TTL/CMOS logic levels to differential RS-485 bus signals for half-duplex communication. The driver and receiver share the A and B bus pins, with DE and RE controls enabling either transmit or receive mode. The 1/4 unit load design reduces input current to 48uA per receiver, enabling 256 nodes on the bus without exceeding the RS-485 32 unit-load limit. The slew-rate-limited driver output slows edge rates to reduce high-frequency content, minimizing EMI and reflections on long cables.

• Industrial automation (Modbus RTU, Profibus)
• Building HVAC and lighting control networks
• Motor drive and inverter communication
• Security system access control networks
• Battery-powered remote sensor networks