VRS interface circuit with differential input and variable hysteresis

This paper describes a Variable Reluctance Sensor (VRS) interface circuit for automotive applications that operates on differential input signals in the range from 200 mV to 250 V. The circuit has a hysteresis that is a fixed ratio of the peak value of the input voltage. The peak voltage is stored on an external RC filter, but otherwise the circuit operation is frequency independent and preserves the timing information of the VRS signal.