Patent ID: 8179106

Claim:
A synchronous-rectifier type DC-DC converter comprising: a high-side main switch element; a low-side rectifying switch element including a rectifying transistor element and a rectifying diode element connected in antiparallel with the rectifying transistor element; and a control drive circuit configured to control an ON/OFF state of the main switch element and the rectifying transistor element, wherein the control drive circuit detects an input voltage to the main switch element and determines the input voltage or a rate of increase in the input voltage, and when the determined value exceeds a predetermined reference value, the control drive circuit releases a complementary ON/OFF operation of the main switch element and the rectifying transistor element and sets a state where both the main switch element and the rectifying transistor element are kept OFF for a time period that is longer than a dead-time during the complementary ON/OFF operation.