| 摘要 |
PROBLEM TO BE SOLVED: To control a rush current during the start-up of a switching power supply circuit with a simple configuration. SOLUTION: An AC voltage of an AC power supply 11 is converted into a DC current by a rectifier smoothing circuit 13. A DC voltage outputted from the rectifier smoothing circuit 13 is supplied to a primary coil L1 of a transformer T so as to turn on/off a switching transistor Q connected to the primary coil L1 in series. A voltage converted into an AC current is fed into a secondary coil L2 of the transformer T. A control part 16 supplies the DC voltage as a DC voltage Vcc of the rectifier smoothing circuit 13 so as to supply a switching signal based on the DC voltage Vcc to the transistor Q. When a DC voltage for operating the control part 16 during the start-up is 12 V, the DC voltage is supplied to the rectifier smoothing circuit 13 via a resistor R1 for suppressing a rush current. When the DC voltage for operating the control part 16 is 18 V, the rush current is suppressed by bypassing the resistor R1. COPYRIGHT: (C)2009,JPO&INPIT
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