The MAX3130/MAX3131 combine an IrDA 1.2 compatible infrared transceiver with an RS-232 interface-all in a single 3V-powered hybrid microcircuit. The infrared transceiver supports IrDA data rates of 2.4kbps to 115kbps. The infrared receive channel provides a high-gain/low-noise PIN-diode amplifier with 100µA of ambient photodiode current rejection at a +3V supply. A high-power LED driver capable of sinking 200mA is included in the infrared transmit path. The on-board encoder/decoder (ENDEC) compresses/stretches signals to and from the external UART, allowing IrDA communication even with non-IrDA UARTs.

A 2-driver/2-receiver RS-232 transceiver supports data rates up to 120kbps. A proprietary, high-efficiency, dual charge-pump power supply and a low-dropout transmitter combine to deliver true RS-232 performance from a single +3.0V to +5.5V supply. Selectable shutdown for IR and RS-232 circuitry reduces supply current to 1µA.

The MAX3130 is optimized for applications using a single UART for both infrared and RS-232 communication. The infrared transmitter input and infrared receiver output are multiplexed with one RS-232 transmitter input and one RS-232 receiver output, respectively. The MAX3131's IrDA transceiver and RS-232 transceivers are separate and have their own data inputs and outputs.

Both these devices require a minimum of external components: four small 0.1µF capacitors, a photodiode, an infrared LED, and a current-setting resistor.