| 摘要 |
PROBLEM TO BE SOLVED: To provide a circuit for suppressing noise and loss by adopting a partially resonant technique in a switching power supply having a separately excited control circuit for detecting voltage generated in the wiring of a transformer for outputting pulses. SOLUTION: A separately excited switching power supply detects the falling signal of a flyback voltage in first feedback wiring 1c for generating pulses, and has a pulse generation circuit 7 for performing feedback control to the width of the pulse so that an output voltage becomes constant. In the switching power supply, delay circuits 11, 12 are inserted so that the falling signal of the flyback voltage in the first feedback wiring 1c enters a pulse generator 7 after a prescribed period; a series circuit comprising a second switching element 13 and a first capacitor 14 is connected in parallel with a first switching element 2; second feedback wiring 1d, which is turned on/off in an opposite phase to the on/off of the first switching element 2, is connected to the control electrode of the second switching element 13; and a second capacitor 15 is connected in parallel with the second switching element 13. COPYRIGHT: (C)2006,JPO&NCIPI
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