| 摘要 |
PROBLEM TO BE SOLVED: To provide a switching power circuit capable of controlling power consumption corresponding to a load state by a simple circuit structure on the secondary side of a high-frequency transformer. SOLUTION: This switching power circuit comprises a field effect transistor F and a high-frequency transformer T connected to the field effect transistor F, and supplies power to a load connected to the secondary side of the high-frequency transformer T, and comprises a resistor R4 for detecting a current for detecting a current change based on the load state, and a voltage-changing means for changing an output voltage between a first voltage and a second voltage which is lower than the first voltage and for changing an output voltage from the first voltage into the second voltage when the current detected by the resistor R4 for detecting the current reaches a predetermined value or smaller. COPYRIGHT: (C)2005,JPO&NCIPI
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