The MAX3140EEI+ is a SPI/MICROWIRE-compatible UART with integrated true fail-safe RS485/RS422 transceiver in 28 pin QSOP package. It includes a single RS485/RS422 driver and receiver featuring true fail-safe circuitry which gives logic-high receiver output when the receiver inputs are open or shorted. This feature provides immunity to faults without requiring complex termination. It provides software-selectable control of half duplex or full duplex operation, data rate, slew rate, transmitter and receiver phase. The RS485 driver slew rate is programmable to minimize EMI and results in maximum data rates of 115Kbps, 500Kbps and 10Mbps. A 1/8-unit-load receiver input impedance allows up to 256 transceivers on the bus. It is used in HVAC and building control, point of sale devices, transceivers for EMI-sensitive applications, embedded systems & intelligent instrumentation.