Ignition Coil Driver

The project presented here is an Ignition coil driver featuring FAN1100-F085 ignition gate driver chip and IGBT. Chip is designed to directly drive an ignition IGBT and control the current and spark event of the coil. The coil current is controlled via the input signal pin. When the input is driven high, the output of the chip is enabled to turn on the IGBT and start charging the coil. Output sink current is programable using resistor R5 (R_A). An input spike filter suppresses input signals of less than 13uS in duration. A Max Dwell timer is included in the chip which will turn off the IGBT if input stays active for longer than the programmable time. This time interval can be modified through an external capacitor on the C_SSD pin. When the Max Dwell timer is exceeded, the CHIP will enter a Soft-Shut-Down mode (SSD) slowly dropping the collector current by lowering the gate drive to the IGBT thereby discharging the coil such as to inhibit a spark event. Once the soft shutdown operation has started, any transition on the input signal is ignored until after the completion of the soft shutdown function. Chip also limits the collector current of the IGBT during charging. This is done through the sense resistor R6 in the emitter leg of the ignition IGBT developing a signal input to the V-Sense pin of the chip.