| 摘要 |
PROBLEM TO BE SOLVED: To provide a rush current limiting/noise reducing circuit for PFM control charge pump in which erroneous operation of other circuits connected with the same power supply as a PFM control charge pump circuit is prevented by suppressing generation of rush current and noise. SOLUTION: A circuit 8 for detecting an input voltage is provided in a PFM control charge pump circuit 15, and gate voltage control circuits 7 and 7a suppress gate voltage of a switching transistor in a charge pump by receiving a signal from the input voltage detecting circuit 8. Potential difference is reduced between the gate terminal and the source terminal. Consequently, the level of a rush current is suppressed and the current is reduced, thus preventing generation of noise. COPYRIGHT: (C)2003,JPO
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