An Analog/Digital Integrated Circuit Interface for Automotive Sensors

A unique and very versatile circuit is described which converts changes in physical parameters such as capacitance, resistance, and inductance into a proportional pulse width modulated digital signal. This circuit, in combination with sensors which utilize these physical parameters in their operation, can be used to provide digital inputs to microprocessors and other digital control and diagnostic systems. Advantages of this particular circuit are its potential for high reliability, accuracy, and low cost. Several applications are described and an integrated circuit version of the circuit is discussed.