| 摘要 |
PROBLEM TO BE SOLVED: To prevent malfunction by noise components with a simple configuration regarding a current detection circuit in a switching power supply. SOLUTION: A series circuit consisting of a first resistor Rs, a second resistor Rt or a zener diode having a smaller resistance as compared with that of the first resistor Rs, and a capacitor Cs is connected in parallel with the secondary winding of a choke coil L for smoothing or a transformer. A voltage Vcs at both the ends of the series circuit of the second resistor Rt or the zener diode, and the capacitor Cs is inputted to a differential amplifier 4 in a switching control section 3 as a current detection voltage having the same phase as a current I flowing to the secondary winding of the smoothing choke coil L or the transformer to control a switching transistor Q in comparison with an error component Ve of an output voltage Vout. COPYRIGHT: (C)2004,JPO&NCIPI
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