| 摘要 |
PROBLEM TO BE SOLVED: To reduce current which is consumed by control of a chopper-type charging circuit. SOLUTION: A comparator COM1 generates a signalϕP1 so that a P-channel FET P1 is turned on, when voltage of an output terminal AG1 of an AC generator AG exceeds voltage of power Vdd. A comparator COM4 generates a signal CN2 becoming a high level, when the voltage of the output terminal AG1 exceeds a reference voltage Vref. An N-channel FETN2 is on/off-controlled through a logic circuit OR2. When the signal CN2 or the output signal of an inversion circuit CN2 becomes the high level in a period when a clock signal CLK becomes the low level, the N-channel FETN2 is turned on. Consequently, even if the operational speed of the comparator COM4 is slow, the N-channel FETN2 is turned on, when the P-channel FETP1 is turned on and current (i) can be charged.
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