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Capacitive Touch Sensing Slide 4

The RO method can be implemented on devices with a comparator or the new PinOsc feature. Please note, in the diagrams shown here, the progression from the Comparator solution that requires external components and connections, to the PinOsc solution, which involves only a single device connection. Sensitivity is directly related to the measurement window (called Gate time here and in the firmware). If the user had an infinitely long gate time one could discern an infinitely small change in capacitance. Longer gate times also means greater noise immunity along with increased power consumption and slower scan rates. The final application needs will determine the tradeoff between power and sensitivity.

PTM Published on: 2012-04-16