DC-DC converter

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.