Patent ID: 7304459

Claim:
A synchronous rectification mode DC-to-DC converter power supply device, comprising: a first switching power supply circuit; and a second switching power supply circuit for carrying out synchronous rectification based on a drive pulse of the first switching power supply circuit, wherein the first switching power supply circuit comprises: an oscillation control circuit operating by a DC input power supply and outputting a drive pulse; a first drive circuit for outputting a drive voltage based on the drive pulse from the oscillation control circuit; a first switching element being driven by the output of the first drive circuit; a first rectifying circuit having a positive electrode being grounded and a negative electrode being connected to the output of the first switching element; and a first coil being connected to the output of the first switching element; and the second switching power supply circuit comprises: a second drive circuit for outputting a drive voltage based on the drive pulse from the oscillation control circuit; a second switching element being driven by the output of the second drive circuit; a second rectifying circuit having a positive electrode being ground and a negative electrode being connected to the output of the second switching element; a third switching element being connected in parallel to the second rectifying circuit and driven by the output of the first drive circuit; and a second coil being connected to the output of the second switching element; and wherein the third switching element is turned on during an OFF period of the first switching element and turned off during an ON period of the first switching element.