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Sensor interface for automotive unbiased capacitive sensors

The interface product portfolio of austriamicrosystems is expanded by adding the AS1716, a sensor designed for interfacing to Piezo Electronic capacitive sensors. Piezo Electronic sensors are self generating and need no external excitation and they are compact and have better linearity. In automotive engine designs the knock sensor is an integral part of the engine management system helping to increase overall reliability and improve fuel efficiency. The sensor operates from a single supply 4.5V to 5.5V. The device provides differential inputs, a first order low pass filter to cut off the high frequency noise components, differential to single ended conversion, programmable gain stage and a two pole low pass multiple feedback filter. The sensor is an analogue front end specifically designed for unbiased capacitive sensors, interfacing with sample and hold input stages and analogue digital converters. The device has been EMC characterised by IEC 61967-4 (1Ohm / 150Ohm method) by IEC 62132-4 (direct power injection), is automotive qualified to AECQ100 for IC and PPAP level 3, and comes in an 8pin SOIC package.