Igniter, igniter control method, and internal combustion engine ignition apparatus

An igniter comprising:

• a main insulated gate transistor that controls the flow of a main current;
• a sense insulated gate transistor that is arranged in parallel to the main insulated gate transistor on the same semiconductor substrate as that on which the main insulated gate transistor is provided and detects a current value of the main insulated gate transistor;
• and
• a control circuit that calculates the current value of the main insulated gate transistor from a sense current value of the sense insulated gate transistor and controls a gate voltage of the main insulated gate transistor on the basis of the calculated current value of the main insulated gate transistor to control the current of the main insulated gate transistor,
• wherein the control circuit reduces the gate voltage output from the control circuit to limit overcurrent which flows to the main insulated gate transistor, and
• the sense current which flows to the sense insulated gate transistor is in a saturation region at a time at which the control circuit reduces the gate voltage to the gate voltage value when the current of the main insulated gate transistor reaches the predetermined upper limit of the overcurrent.

An igniter comprising:

• a main insulated gate transistor including a first semiconductor layer of a first conductivity type, a second semiconductor layer of a second conductivity type that is selectively provided in a surface layer of a first main surface of the first semiconductor layer, a third semiconductor layer of the first conductivity type that is selectively provided in the second semiconductor layer, a first gate electrode that is provided on a surface of a portion of the second semiconductor layer which is interposed between the third semiconductor layer and the first semiconductor layer, with a first gate insulating film interposed therebetween, and a first main electrode that is electrically connected to the second semiconductor layer and the third semiconductor layer;
• and
• a sense insulated gate transistor including a fourth semiconductor layer of the second conductivity type that is selectively provided in the surface layer of the first main surface of the first semiconductor layer so as to be separated from the second semiconductor layer, a fifth semiconductor layer of the first conductivity type that is selectively provided in the fourth semiconductor layer, a second gate electrode that is provided on a surface of a portion of the fourth semiconductor layer which is interposed between the fifth semiconductor layer and the first semiconductor layer, with a second gate insulating film interposed therebetween, and a second main electrode that is electrically connected to the first main electrode, the fourth semiconductor layer, and the fifth semiconductor layer,
• wherein a distance between the main insulated gate transistor and the sense insulated gate transistor is equal to or greater than 100 μm and equal to or less than 700 μm.

An internal combustion engine ignition apparatus comprising:

• an igniter,
• wherein the igniter includes:
• a main insulated gate transistor that controls the flow of a main current;
• a sense insulated gate transistor that is arranged in parallel to the main insulated gate transistor on the same semiconductor substrate as that on which the main insulated gate transistor is provided and detects a current value of the main insulated gate transistor;
• and
• a control circuit that calculates the current value of the main insulated gate transistor from a sense current value of the sense insulated gate transistor and controls a gate voltage of the main insulated gate transistor on the basis of the calculated current value of the main insulated gate transistor to control a current of the main insulated gate transistor, and
• the igniter is controlled such that, before overcurrent flows to the main insulated gate transistor and a value of the overcurrent reaches a predetermined upper limit, the control circuit calculates the current value of the main insulated gate transistor from the sense current value of the sense insulated gate transistor and reduces the gate voltage so that the current of the main insulated gate transistor reaches the predetermined upper limit of the overcurrent.