| 摘要 |
PROBLEM TO BE SOLVED: To provide a control circuit for a switching power-supply circuit, which improves responsiveness of control at a light load and achieves stability of control at a heavy load. SOLUTION: The control circuit for the switching power-supply circuit is driven by either a light-load mode having a relatively small load current IOUT and a heavy-load mode having a relatively large load current. The control circuit for the switching power-supply circuit has a capacitor C1 for compensating the phase of an error amplifier 1, the capacitor C2 connected in parallel with the capacitor C1 through a switching element SW1 and a voltage adjusting means I adjusting the charge voltage of the capacitor C2 so as to be equal to that of the capacitor C1. The control circuit for the switching power-supply circuit has also a state decision circuit 8 detecting whether the light-load mode or the heavy-load mode is selected and compensating the phase using the capacitor C1 by turning off the switching element SW1 in the light-load mode, while compensating the phase using the capacitor C1 and the capacitor C2 by turning on the switching element SW1 in the heavy-load mode. COPYRIGHT: (C)2010,JPO&INPIT
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