Impact sensor.

摘要

A single-point impact sensor (10) has a fully differential capacitive sense element (12) for providing a capacitive difference which is proportional to the acceleration of the vehicle. The capacitive difference is converted into a digital pulse train signal which is pulse density modulated with variations in the capacitance. The pulse density of the pulse train is evaluated according to a hierarchy of counters and timers to determine if it is indicative of an activation worthy event. In one embodiment, a non-volatile programmable memory (140) is provided to control the operation of the impact sensor.