For side airbag systems, it is necessary to measure the acceleration within a time of less than 3 ms in order to inflate the side airbag in time. In this paper, a new generation of side airbag sensors that uses a linear accelerometer is presented. The evaluation circuit includes amplification, temperature coefficient compensation, two wire unidirectional current interface, and a zero-offset compensation. The sensing element for the measurement of acceleration is a surface micromachined accelerometer. The surface micromachined sensor element and the corresponding evaluation ASIC (Application Specific Integrated Circuit) are packaged into a standard PLCC28 housing in order to minimise the production costs. For the entire function, only few external components are necessary. During the power-on cycle, an internal selftest is carried out, and the result is transmitted to the airbag control unit. Most important results of the characterisation are presented. (A)
Samenvatting