Patent ID: 7538531

Claim:
A drive circuit for driving a first switch having a first terminal, a second terminal, and a control terminal, wherein a direct-current voltage from a first direct-current power supply is applied to the first terminal, the drive circuit comprising: a capacitor which is charged when the first switch is in the OFF state, and applies a charged voltage between the control terminal and the second terminal of the first switch when the first switch is in the ON state; a second direct-current power supply; a second switch which is connected between a positive terminal of the capacitor and a positive terminal of the second direct-current power supply, and goes to the ON state when the first switch is turned OFF; a third switch which is connected between a negative terminal of the capacitor and a negative terminal of the second direct-current power supply, and goes to the ON state when the first switch is turned OFF; a fourth switch which is connected between the positive terminal of the capacitor and the control terminal of the first switch, and goes to the ON state when the first switch is turned ON; and a fifth switch which is connected to the negative terminal of the capacitor and the second terminal of the first switch, and goes to the ON state when the first switch is turned ON.