Control circuit for controlling power supplied to an igniter element and igniter system

An igniter device comprising a semiconductor igniter element and a control circuit for controlling power supplied to the semiconductor igniter element, the control circuit comprising:

• a first input for receiving an encoded input signal generated in response to the initiation of a firing mode and a diagnostic mode, the encoded input signal comprising a code portion and a power portion, the code portion comprising n pulses having substantially a predetermined frequency, where n is at least two;
• logic means for determining whether the code portion of the received encoded input signal is valid, the code portion being determined valid when the code portion meets predefined conditions within a predetermined time window and for providing an unlocking signal at an output when the code portion is determined to be valid;
• and
• a switch having a control input coupled to the output of the logic means, an input coupled to the first input of the control circuit, and an output for coupling to the igniter element, wherein the switch is enabled on receipt of the unlocking signal such that in the firing mode power, including the power portion of the received encoded input signal, at the first input of the control circuit is supplied to the output of the switch for firing the igniter element and in the diagnostic mode the power portion of the received encoded input signal is supplied to the output of the switch for energizing the igniter element.

An igniter system comprising:

• a control circuit for controlling power supplied to an igniter element, the control circuit comprising:
• a first input for receiving an encoded input signal generated in response to the initiation of a firing mode and a diagnostic mode, the encoded input signal comprising a code portion and a power portion, the code portion comprising n pulses having substantially a predetermined frequency, where n is at least two;
• logic means for determining whether the code portion of the received encoded input signal is valid, the code portion being determined valid when the code portion meets predefined conditions within a predetermined time window and for providing an unlocking signal at an output when the code portion is determined to be valid;
• and
• a switch having a control input coupled to the output of the logic means, an input coupled to the first input of the control circuit, and an output for coupling to the igniter element, wherein the switch is enabled on receipt of the unlocking signal such that in the firing mode power, including the power portion of the received encoded input signal, at the first input of the control circuit is supplied to the output of the switch for firing the igniter element and in the diagnostic mode the power portion of the received encoded input signal is supplied to the output of the switch for energizing the igniter element;
• an igniter element coupled to the output of the switch of the control circuit such that when the control circuit switch is enabled power is supplied to the igniter element;
• a power switch coupled to the first input of the control circuit and a first voltage supply, the power switch when enabled providing a power signal to the first input of the control circuit;
• a processing unit for generating the encoded input signal generated in response to the initiation of a firing mode and a diagnostic mode and for providing the encoded input signal to the first input of the control circuit, for providing a control signal to the power switch to enable the power switch in response to the initiation of the firing mode, and for monitoring a voltage signal across the igniter element in the diagnostic mode, wherein in the firing mode the power signal at the first input of the control circuit is supplied with the power portion of the encoded input signal to the igniter element when the control circuit enables the control circuit switch to fire the igniter element, and wherein in the diagnostic mode the processing unit does not enable the power switch wherein only the power portion of the encoded input signal is provided to the igniter element when the control circuit enables the control circuit switch.