Igniter circuit having an adjustable over dwell time
AssigneeSemiconductor Components Industries, LLC
InventorHirotada Honma
Life of this patent
Estimating the term…
Abstract
An ignition system may include an igniter circuit to control the current in a coil supplied by a battery based on an input signal from an engine control unit. To prevent overheating, the igniter circuit may be configured to shut down the current in the coil when the input signal is held high for an over dwell period. The disclosed igniter circuit is configured with circuitry to automatically adjust the over dwell period used based on a condition of the battery to prevent overheating without prematurely shutting down. The automatic adjustment includes indirectly monitoring the battery condition based on a current or a voltage of a switching device coupled to the coil.
Claims20
A method, comprising:
- receiving an input signal to configure a switching device in an ON condition, the switching device coupled in series with a coil;
- starting a timer;
- sensing a current in the coil after the switching device is configured in the ON condition;
- measuring, based on the timer, a rise time corresponding to a time for the current to satisfy a criterion;
- calculating a soft-shutdown delay based on the rise time;
- and
- starting a soft-shutdown to reduce the current in the coil after the soft-shutdown delay.
An ignition system, comprising:
- a coil coupled at a first side to a battery;
- and
- an igniter circuit including:
- a switching device coupled to a second side of the coil;
- a current controller configured to control a current condition of the switching device;
- and
- an over dwell circuit configured to:
- measure a rise time of a current conducted by the switching device after being configured in an ON condition;
- and
- trigger the current controller to start a soft shutdown of the current after a soft-shutdown delay, the soft-shutdown delay based on the rise time of the current.
Dependencies are inferred from the claim text.