Short-circuit protection circuit, semiconductor device, and short-circuit protection method

A semiconductor device comprising:

• a semiconductor switch element;
• a voltage dividing circuit that divides a power supply voltage supplied from a power supply connected to one end thereof;
• a semiconductor rectifying element, one end of which is connected between resistance elements of the voltage dividing circuit and the other end of which is connected onto a path of a conductive wire connected to a current-inflow-side terminal of the semiconductor switch element, the connection being made such that a direction from the one end to the other end becomes a rectifying direction;
• an RC parallel circuit connected to the other end of the voltage dividing circuit;
• and
• a drive unit that turns off the semiconductor switch element when it is detected that a short-circuit current flows through the conductive wire, on the basis of a voltage of a capacitor element included in the RC parallel circuit, in a case in which the semiconductor switch element is turned on,
• wherein the voltage dividing circuit includes a resistance element of which one end is directly connected to the power supply, wherein the one end of the semiconductor rectifying element is connected to the other end of the resistance element, and wherein, in a case in which a resistance value of the resistance element is R1, a voltage value of the power supply voltage is VCC, a capacitance of the capacitor element of the RC parallel circuit is C1, a voltage change between the current-inflow-side terminal of the semiconductor switch element and a current-outflow-terminal of the semiconductor switch element is dVds/dt, and the stray capacitance of the semiconductor rectifying element is Cd1,
• Cd1 satisfies a conditional expression of 1/{(3×dVds/dt×R1)/VCC−1/C1}>Cd1.

A short-circuit protection method,

• wherein a voltage dividing circuit divides a power supply voltage supplied from a power supply connected to one end thereof,
• wherein a capacitor element included in an RC parallel circuit connected to the other end of the voltage dividing circuit is charged on the basis of a current supplied,
• wherein, a semiconductor rectifying element in which a direction from one end to the other end becomes a rectifying direction, and in which the one end is connected between resistance elements of the voltage dividing circuit and the other end is connected onto a path of a conductive wire connected to a current-inflow-side terminal of a semiconductor switch element to be protected and which conducts a current in the rectifying direction in a case in which a voltage at the one end thereof is higher than a voltage at the other end thereof, and wherein a drive unit turns off the semiconductor switch element when it is detected that the short-circuit current flows through the conductive wire, on the basis of a voltage of the capacitor element included in the RC parallel circuit, in a case in which the semiconductor switch element is turned on
• wherein the voltage dividing circuit includes a resistance element of which one end is directly connected to the power supply, wherein the one end of the semiconductor rectifying element is connected to the other end of the resistance element, and wherein, in a case in which a resistance value of the resistance element is R1, a voltage value of the power supply voltage is VCC, a capacitance of the capacitor element of the RC parallel circuit is C1, a voltage change between the current-inflow-side terminal of the semiconductor switch element and a current-outflow-terminal of the semiconductor switch element is dVds/dt, and the stray capacitance of the semiconductor rectifying element is Cd1,
• Cd1 satisfies a conditional expression of 1/{(3×dVds/dt×R1)/VCC−1/C1}>Cd1.