Eliminate stand-by modes with low-current, self-calibrating touch and proximity switches

September 04, 2013 // By Paul Buckley
NXP Semiconductors has introduced a family of self-calibrating capacitive touch and proximity switches designed for harsh environments.

PCF8883 and PCF8885, along with the automotive-grade PCA8885 and PCA8886, enable robust sensing despite dust, moisture, grease and other types of contamination building up on the touch area, and offer high immunity to sudden temperature changes and to electromagnetic interference. Using digital signal processing to detect changes in capacitance on a remote sensing plate, NXP’s capacitive touch switches eliminate the need for a microcontroller and firmware for post-processing. With very low power consumption – typically 3 μA per channel – NXP’s capacitive touch and proximity switches can also run continuously, with no complicated power-down and wake-up schemes required.

The sampling frequency and response times are adjustable, allowing you to configure the PCF8883, PCF8885, PCA8885 and PCA8886 for a wide range of industrial and automotive applications. The single-channel PCF8883 and dual-channel PCA8886 can be used as touch switches, or as proximity sensors which wake up and reactivate the system from power-down mode. The multi-channel PCF8885 can be used as a slider, as a rotary wheel and for dedicated touch keys.      

NXP’s robust capacitive touch and proximity switches are suited to applications using touch screen control panels, including: Home appliances such as washing machines, ovens and vacuum cleaners; Building control systems for heating, ventilation and air conditioning (HVAC) and lighting; Industrial equipment such as automated teller machines (ATMs); Medical devices such as blood pressure monitors and automotive applications such as climate control units, car entertainment systems, car access systems, and mirror and sun-roof control units

For the NXP OM11057 demo board for PCF8883, PCF8885 and PCA8886: www.nxp.com/demoboard/OM11057.html