AS1716 is an analog front end specifically designed for unbiased Capacitive Sensors, as for instance Knock Sensors in Automotive, to be interfaced with Analog Digital Converters with Sample and Hold input stages.
The device provides differential inputs, a 1st order low pass filter to cutoff the high frequency noise components, differential to single ended conversion, programmable gain stage and a 2 pole low pass Multiple Feedback Filter.
The Knock Sensor is a Piezo Electric device that generates a voltage if it is stressed. It senses knock and transmits information to the electronic engine management control unit. This influences process control in the engine, for example timing and fuel injection until knock is eliminated.
The capacitive sensor is biased via resistors to a voltage level of VDDA/2.
Analog front end for Capacitive Sensors to Analog to Digital Converters and DSP.
AS1716 Capacitive Sensor Interface Block Diagram
