Automotive ignition system with adaptable start-of-dwell ring damping

Abstract

An automotive ignition system includes a control circuit ( ) operable to drive a coil current switching device ( ) connected to an ignition coil ( ) referenced at battery voltage. The control circuit ( ) includes a drive circuit ( ) and ring damping circuit ( ) producing an inhibit signal (INH) to which the drive circuit ( ) is responsive to control the state of the coil drive signal (GD). In a single pulse ignition system; i.e., an ignition system employing a single coil charging event per combustion cycle, the ring damping circuit ( ) is responsive to a spark control signal (ESTBF) to control charging and discharging of a single capacitor (C ) to define the inhibit signal (INH). In a multiple pulse ignition system; i.e., an ignition system employing multiple coil recharging cycles following a standard initial charging dwell cycle, the ring damping circuit ( ) is responsive to the spark control signal (ESTBF) and at least two mode signals (M M ) to control charging and discharging of the single capacitor (C ) throughout the initial and subsequent coil charging cycles to define the inhibit signal (INH). In either case, the drive circuit ( ) is responsive to the inhibit signal (INH) to disable current flow through the primary ignition coil ( ) when the inhibit signal (INH) is enabled, and to enable current flow through the primary ignition coil ( ) when the inhibit signal (INH) is disabled.