| 摘要 |
A switching power source apparatus has a switching element being connected with a DC power source through a primary winding of a transformer in which parasitic capacitance exists between terminals of the switching element. A voltage V 4 of free oscillation appears at a gate of the switching element after a flyback period due to the parasitic capacitance. Based on the free oscillation voltage, the switching power source apparatus detects timing synchronized with a period of the free oscillation, outputs a trigger signal V 10 based on the detected timing, uses the trigger signal to estimate bottom timing when the free oscillation reaches a bottom level the second time, outputs an ON start signal V 9 synchronized with the bottom timing, uses the ON start signal to output an ON control signal to turn on the switching element, and drives the switching element in response to the ON control signal.
|
