Patent ID: 7474543
Filing Date: 2009-01-06
Classification: H02M,Y02B

Abstract:
1. An isolated DC-DC converter comprising: a transformer including an electromagnetically coupled primary coil, secondary coil, and tertiary coil; a main switching device arranged on a side of the primary coil of the transformer to control energy supplied from an external power supply to the primary coil by a switching operation to control a voltage generated in the primary coil; a secondary-side rectifying and smoothing circuit arranged to rectify and smooth an output voltage from the secondary coil corresponding to the voltage of the primary coil of the transformer and output a rectified and smoothed voltage to an external load; a tertiary-side rectifying and smoothing circuit arranged to rectify and smooth an output voltage from the tertiary coil to produce a direct-current voltage, and detect and output the direct-current voltage as a detected voltage of the output voltage from the secondary-side rectifying and smoothing circuit; and a control circuit arranged to control the switching operation of the main switching device on the basis of the detected voltage output from the tertiary-side rectifying and smoothing circuit so that the output voltage from the secondary-side rectifying and smoothing circuit is stabilized; wherein the secondary-side rectifying and smoothing circuit includes a rectification-side synchronous rectifier and a commutation-side synchronous rectifier that perform a switching operation in synchronization with the switching operation of the main switching device to rectify the output voltage from the secondary coil; and the tertiary-side rectifying and smoothing circuit includes a commutation-side synchronous rectifier to rectify the output voltage from the tertiary coil, the commutation-side synchronous rectifier being arranged to be switched on when the main switching device is turned off.