Abstract: A current leakage detection circuit that detects current leakage from a battery having a first electrode and a second electrode, which is either the positive electrode or the negative electrode opposite to the first electrode, to a chassis includes: a detection circuit including a reference voltage source terminal, a first detection terminal, and a ground terminal connected to the first electrode; a first resistor connected between the second electrode and the chassis; a second resistor connected between the chassis and the first detection terminal; and a third resistor connected between the first detection terminal and a predetermined terminal. When the first electrode is the positive electrode, the predetermined terminal is the reference voltage source terminal. When the first electrode is the negative electrode, the predetermined terminal is the first electrode. The detection circuit detects an occurrence of current leakage based on a voltage of the first detection terminal.

Abstract: A power supply protection circuit is a circuit that controls a protection switch provided on a power supply line connecting a direct current power supply and a load circuit. The power supply protection circuit includes: circuitry connected to the protection switch; and a controller that switches an operation state of the circuitry between a first state and a second state. The first state is an operation state in which driving of the protection switch is enabled when the protection switch is a first semiconductor switch having a control terminal connected to a semiconductor layer of a first conductivity type. The second state is an operation state in which driving of the protection switch is enabled when the protection switch is a second semiconductor switch having a control terminal connected to a semiconductor layer of a second conductivity type that is different from the semiconductor layer of a first conductivity type.

Abstract: A driver circuit which is supplied with a positive power supply voltage, a negative power supply voltage, and an input signal, and drives a switching element including a control terminal according to the input signal includes: a first output terminal connected to the control terminal via a first impedance circuit, and outputs the positive power supply voltage or the negative power supply voltage according to the input signal, to charge the control terminal and put the switching element into an ON state; a negative power supply terminal supplied with the negative power supply voltage; a negative voltage switch having a first end connected to the negative power supply terminal; a third output terminal connected to a second end of the negative voltage switch and to the control terminal via a second impedance circuit; and a first discharge switch disposed between the negative power supply terminal and the first output terminal.

Abstract: A power supply protection circuit is a circuit that controls a protection switch provided on a power supply line connecting a direct current power supply and a load circuit. The power supply protection circuit includes: circuitry connected to the protection switch; and a controller that switches an operation state of the circuitry between a first state and a second state. The first state is an operation state in which driving of the protection switch is enabled when the protection switch is a first semiconductor switch having a control terminal connected to a semiconductor layer of a first conductivity type. The second state is an operation state in which driving of the protection switch is enabled when the protection switch is a second semiconductor switch having a control terminal connected to a semiconductor layer of a second conductivity type that is different from the semiconductor layer of a first conductivity type.

Abstract: A driver circuit which is supplied with a positive power supply voltage, a negative power supply voltage, and an input signal, and drives a switching element including a control terminal according to the input signal includes: a first output terminal connected to the control terminal via a first impedance circuit, and outputs the positive power supply voltage or the negative power supply voltage according to the input signal, to charge the control terminal and put the switching element into an ON state; a negative power supply terminal supplied with the negative power supply voltage; a negative voltage switch having a first end connected to the negative power supply terminal; a third output terminal connected to a second end of the negative voltage switch and to the control terminal via a second impedance circuit; and a first discharge switch disposed between the negative power supply terminal and the first output terminal.