Patent ID: 7821236

Claim:
A DC-DC converter performing pulse width modulation or pulse frequency modulation and outputting an output voltage via a choke coil, the DC-DC converter comprising: a first transistor receiving an input voltage; a second transistor coupled to the first transistor, the choke coil being coupled to a node between the first and second transistors; a drive control circuit, coupled to the first and second transistors, generating a first drive signal and a second drive signal activating and inactivating the first transistor and the second transistor in a complementary manner; a reversed flow detection circuit detecting current flowing to the second transistor and generating a detection signal controlling activation and inactivation of the second transistor; and a detection signal invalidation circuit, coupled to the reversed flow detection circuit and the drive control circuit, invalidating the detection signal in response to an operation switch signal during the pulse width modulation.