MAX3140EEI

The MAX3140EEI from Analog Devices (Maxim Integrated) is a versatile component combining a Universal Asynchronous Receiver-Transmitter (UART) with a true fail-safe RS-485/RS-422 transceiver. This integration is achieved within a compact 28-pin QSOP package, making it suitable for applications where space, cost, and power consumption are critical.

The device supports an SPI/QSPI/MICROWIRE-compatible serial interface, which helps conserve microcontroller I/O pins. It offers software-selectable control over half- or full-duplex operation, data rate, slew rate, and transmitter/receiver phase. The RS-485 driver supports maximum data rates of 115kbps, 500kbps, and 10Mbps, with programmable slew rate control to minimize EMI. The receiver features true fail-safe circuitry, ensuring a logic-high output when inputs are open or shorted, thus eliminating the need for complex termination.

The integrated UART includes a baud-rate generator with programmable dividers for rates up to 230k baud and an 8-word receive FIFO to reduce processor overhead. It operates from a single +5V supply, consuming a typical 645µA with the receiver active and reducing to 20µA in hardware shutdown mode. The MAX3140EEI allows up to 256 transceivers on the bus due to its 1/8-unit-load receiver input impedance.

This transceiver is ideal for industrial control, local area networks, HVAC and building control, embedded systems, point-of-sale devices, and intelligent instrumentation applications requiring robust serial communication.