| 摘要 |
PROBLEM TO BE SOLVED: To shorten the time, from start to when a constant voltage output becomes available, in a DC-DC converter circuit of a chopper-type PWM method that is equipped with a soft start circuit. SOLUTION: Between a capacitor C13, constituting an integration circuit 30 and the GND, a charging time shortening circuit 40 is provided, which reduces the charging time with the capacitor C13 of the integration circuit 30 during the period; while a CS terminal voltage (control voltage of soft-start circuit) of PWM control circuit IC1 rises, up to near the operation start voltage of the soft start circuit from the time point, when an input voltage Vin is applied. The charging time shortening circuit 40 comprises a diode D2 for shortening the charging time, of which the anode is connected to the negative side of capacitor C13, while the cathode is connected to GND so that the forward current will flow, as the input voltage Vin is applied. COPYRIGHT: (C)2006,JPO&NCIPI
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