A touch-sensitive switch is a switch that is implemented as a trace on a printed circuit board (PCB). The architecture of the trace creates a capacitive element on the board, which, when touched, creates a change in capacitance. Touch-sensitive switches are found in a variety of consumer products, from home appliances to MP3 players.


This application note covers the following topics: creating a touch sensitive switch with a relaxation oscillator; adding a single or multiple touch sense switches to a design; the most effective layout patterns for a switch; and the effects on sensitivity of different types of materials used on top of the switches.