| 摘要 |
PROBLEM TO BE SOLVED: To obtain a switching power supply stabilized over a wide range of fluctuation for different loads and supplying power stably even for dynamic fluctuation of a load. SOLUTION: In a switching power supply 10, a microcomputer 13 calculates a gain correction coefficient g (=PWMn-1/Ifb) based on a previous PWM duty PWMn-1 and an output value thereof, i.e., a current detection value Ifb and corrects a control gain G with the gain correction coefficient to determine a corrected control gain (=G/g). When the corrected control gain (=G×g) exceeds a predetermined value GSL, a corrected valueΔof PWM duty is calculated by substituting the predetermined value GSL for the corrected control gain (=G×g) and then the previous PWM duty PWMn-1 is corrected based on the corrected valueΔof PWM duty thus determining a PWM duty PWMn.
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