Patent ID: 8971071
Filing Date: 2015-03-03
Classification: H02H,H02M,H03K

Abstract:
1. A driver circuit that includes a first switching element having a pair of input-output terminals, one end of which is connected to a first power-supply voltage, and a second switching element connected in series to the other end of the pair of input-output terminals of the first switching element, and that outputs a voltage of an intermediate node between the first switching element and the second switching element, the first and the second switching elements including wide-gap semiconductor, and having a normally-on characteristic, the driver circuit comprising: a third switching element having a normally-off characteristic, and having a pair of input-output terminals, one end of which is connected to one end, not connected to the first switching element, of the input-output terminals of the second switching element, and the other end of which is connected to a second power-supply voltage lower than the first power-supply voltage; a first control circuit that outputs a first control signal for controlling on/off of the first switching element to a control terminal of the first switching element based upon an input signal; a second control circuit that outputs a second control signal for controlling on/off of the second switching element to a control terminal of the second switching element based upon an input signal; a third control circuit that outputs a third control signal for controlling on/off of the third switching element to a control terminal of the third switching element; and a control-circuit power supply that supplies an operating voltage required for operations of the first control circuit and the second control circuit, wherein the third control circuit compares the operating voltage with a predetermined value, and when the operating voltage is insufficient for an operation of the control circuit as a result of the comparison, the third control circuit turns off the third switching element.