Schurter CPS Series illuminated switches

The Schurter CPS series switches are capacitive touch sensors that can be used as momentary push buttons (NO or NC) or as latching switches (LA) with multicolor illumination. In these switches, there is no NPN/PNP built-in. It’s different circuitry involved that directly ties the control of illumination with the switching function.

This switch is wired such that when the different wires for the RGB goes to ground, it will illuminate. For more details, please refer to its datasheet.


This switch can work with a PLC with NPN transistor outputs (open collector with the emitter tied to ground). It can be used with a microcontroller to sense inputs and drive the LED outputs as below.

This switch will turn the respective LED ON when it senses that the LED input wire is pulled down to ground, and it will turn the LED OFF when it senses that the LED input wire is left floating (internal pull-up resistor pulls the microcontroller input up to 3.3V).

An open collector NPN transistor can do this. When the transistor is OFF, it is essentially an open circuit, and when ON, it will pull the collector almost to ground (typically 0.1V to 0.2V). Below is a recommended schematic for the LED control.