| 摘要 |
PROBLEM TO BE SOLVED: To reduce switching loss under light load by prolonging charging time during intermittent operation, and to shorten the starting time simultaneously. SOLUTION: Immediately after the power supply is turned on, the voltage of an auxiliary power supply terminal VDD does not reach a threshold value voltage Vchgoff which makes the switching circuit (PchMOSFETP12) of a current control circuit 14 nonconductive, charging current is supplied to the auxiliary power supply terminal VDD from a first and a second current sources to start charging a capacitor C3 connected to the terminal. When the capacitor C3 is charged and the terminal voltage of the auxiliary power supply terminal VDD reaches the upper limit of the threshold value voltage Vchgoff of a hysteresis comparator 141, the switch circuit becomes nonconductive, permitting the capacitor C3 to be charged only with the charging current from the first power supply due to the separation of the second power supply (PchMOSFETP11) from the auxiliary power supply terminal VDD. COPYRIGHT: (C)2005,JPO&NCIPI
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