Application Note AN4313
November 2013
This application note describes the layout and mechanical design guidelines used for touch sensing applications with projected sensors.
This document describes only what is specifically related to projected sensors, designed using STM8L52/L53 microcontrollers. To have general tips and tricks for designing touch application, please refer to application note AN4312.
There is a sampling capacitor which stores the charges coming from the electrodes which form a coupling capacitor with less capacitance than the sample one. When a finger approaches, the dielectric (between the two electrodes) is modified and so the capacitance decreases. As a consequence, the time taken to load the sample capacitor will increase and this difference is used to detect if a finger is present or not.
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Related datasheets:
Electric field between 2 surface electrodes
