| 摘要 |
PROBLEM TO BE SOLVED: To simplify circuitry and further reduce power loss by series- connecting a starting voltage supplying capacitor for supplying a starting voltage to a control circuit with a smoothing capacitor for smoothing the input power supply of a switching regulator. SOLUTION: A starting circuit 19 is provided with a protective element 16 parallel-connected with a starting voltage supplying capacitor 15 for supplying a starting voltage V1 to a control circuit 10. For the reason, there is not a transistor for starting, a starting resistor or a Zener diode provided and the circuitry is simple. Power loss due to these elements does not occur and consideration to damage to the transistor for starting is unnecessary. Since the staring voltage supplying capacitor 15 is series-connected with the smoothing capacitor 14, starting power V1 supplied to the control circuit 10 is determined by the output voltage V0 from a rectifier 13, the capacitance C1 of a smoothing capacitor 14, and the capacitance C2 of the starting power supplying capacitor 15.
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