| 摘要 |
PROBLEM TO BE SOLVED: To provide a flyback type power supply unit capable of unfailingly controlling the operation of a synchronous rectifier element synchronously with the changeover of a primary side operation, and reducing the number of parts and reducing a mounting area. SOLUTION: The flyback type power supply unit 10 having the synchronous rectifier element SW12 includes an off-timing detecting circuit 21 for detecting a voltage vibration generated in a secondary winding N12 of a transformer T11 when a switching element SW11 of a primary side is turned on by an action of a leakage inductance generated in a secondary winding L12 of the transformer T11 and outputting an off-trigger signal. Then, the synchronous rectifier element SW12 is turned off based on the off-trigger signal. COPYRIGHT: (C)2010,JPO&INPIT
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