| 摘要 |
PROBLEM TO BE SOLVED: To reduce switching loss at the time of normal mode, and noise due to switching operation, while dealing with instantaneous peak load.SOLUTION: A switching power supply device includes a bottom detection circuit (2) outputting a first control signal for turning a switching element (Q) on, at such a timing as the resonance voltage based on the resonance of a primary winding (PP1) and a capacitor (Cr) exhibiting a bottom, and a switching period limit circuit (3) outputting a second control signal for turning the switching element (Q) on, at such a timing as the switching period of the switching element (Q) reaches a predetermined upper limit.SELECTED DRAWING: Figure 1 |
