Spark Ionization Controller for Vehicle Ignition Systems

This paper describes the function and performance of the A103 Ionization Control Integrated Circuit, a custom mixed technology (Bipolar/CMOS) device developed for use in a closed loop automotive ignition system. The A103 serves as a drive and control intermediary between the relatively benign world of the engine control microprocessor and the considerably harsher environment of the ignition coil and its drive transistors. With increased integration of the ignition control system onto the IC, the A103 delivers greater functionality with higher reliability at a lower component count, a smaller footprint, and at a lower cost than previous discrete solutions. The device enables accurate, real-time adjustment of ignition timing and dwell, as well as control of coil primary current and its charge time, throughout the life of the vehicle.