Maxim Integrated's MAX31915 translates and conditions the 24 V digital output of sensors and switches used in industrial, process, and building automation to 5 V CMOS-compatible signals required by microcontrollers. It provides the front-end interface circuit of a programmable logic controller (PLC) digital input module.

The signal voltage translation is performed in conjunc­tion with input current limiting and lowpass filtering. Input current-limiting allows a significant reduction in power consumed from the field-supply voltage, as compared to traditional discrete resistor-divider implementations.

Selectable on-chip lowpass filters allow flexible debouncing and filtering of sensor inputs based on the application. When no filtering is selected, the IC is capable of detecting pulses as short as 0.75 μs at its field inputs.

All eight input channels are translated to CMOS logic levels and are presented in parallel on the eight output pins for direct or galvanically-isolated interface with a controller ASIC or micro.

The on-chip 5 V voltage regulator can be used to power external optocouplers, digital isolators, or other external 5 V circuitry.