| 摘要 |
PROBLEM TO BE SOLVED: To provide a synchronous rectifying and driving circuit having the high efficiency and a simple circuit configuration. SOLUTION: A transformer T2 is installed in an output smoothing section of a switching power supply wherein synchronous rectification is applied and the driving voltage is supplied to a FET for current circulation of the transformer. As a result, a FET for rectification and the FET for circulation are alternately turned on and off and therefore, there is no period wherein the driving voltage for the FET for circulation becomes zero. Consequently, there is no period wherein a body diode of the FET for circulation is turned on, thereby maintaining the high efficiency.
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