| 摘要 |
<p>PROBLEM TO BE SOLVED: To suppress an output voltage fluctuation at the shift of an operation mode.SOLUTION: In a step-up shift period shifting from step-down mode operation to step-up mode operation, a power control circuit 4 is operated in a fixed-duty step-up mode for driving a step-up transistor T2 at on duty fixed to 5%, irrespective of the control of an error amplifier 13. In a step-down shift period shifting from the step-up mode operation to the step-down mode operation, the power control circuit 4 is operated in a fixed-duty step-down mode for driving a step-down transistor T1 at on duty fixed to 95% irrespective of the control of the error amplifier 13.</p> |
