| 摘要 |
PROBLEM TO BE SOLVED: To attain satisfactory control with precision with a structure having a small number of parts. SOLUTION: This control circuit includes a comparator 3, detecting whether the output of a current detector 2 exceeds a peak detection level, a comparator 4 detecting whether the output of the current detector 2 falls below trailing edge detection level an RS latch 5 in which a Q terminal is connected to the gate of FETQ1, an on-timer 6 disposed between the output terminal of the comparator 3 and the R terminal of the RS latch 5, and an off-timer 7 disposed between the output terminal of the comparator 4 and the S terminal of the RS latch 5. The on-timer 6 is formed out of a reference voltage circuit 61 switching between first lower limit reference voltage and first upper limit reference voltage for output, a capacitor C6, a charging/discharging circuit 62 of charging/discharging it, and a comparator 63. The off-timer 7 is formed a reference voltage circuit 71 switching from second lower limit reference voltage and second upper limit reference voltage for output, a capacitor C7, a charging/ discharging circuit 72 of charging/discharging it, and a comparator 73.
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