Patent ID: 8780517

Claim:
A semiconductor apparatus comprising: a power transistor that is placed between an input terminal and an output terminal; a temperature detection diode that has a cathode connected to the input terminal and an anode connected to the output terminal; a current amplifier that outputs a detection current generated by amplifying a backward leakage current flowing from the cathode to the anode of the temperature detection diode; a first conversion resistor that outputs an overheat detection signal generated by converting the detection current into a voltage; a gating circuit that performs gating of a control signal according to the overheat detection signal: a driver circuit that outputs a drive signal to a control terminal of the power transistor based on an output signal of the gating circuit; and an overvoltage protection circuit configured to prevent breakdown current flowing to the temperature detection diode when a drain-source voltage of the power transistor becomes equal to or higher than a breakdown voltage, wherein the current amplifier includes a second conversion resistor that is connected between the cathode of the temperature detection diode and the input terminal and generates a leakage voltage by converting the backward leakage current into a voltage, wherein the overvoltage protection circuit comprises: an overvoltage protection diode that has a cathode connected to the input terminal and an anode connected to the output terminal; a fourth conversion resistor that is placed between the input terminal and the cathode of the overvoltage protection diode and generates an overvoltage detection signal by converting a current flowing through the overvoltage protection diode into a voltage; and an overvoltage protection transistor that is placed between the cathode of the overvoltage protection diode and the second conversion resistor of the current amplifier and has a conduct state controlled based on the overvoltage detection signal.