| 摘要 |
PROBLEM TO BE SOLVED: To improve drooping characteristics of an output voltage of a power supply circuit when executing constant-current control on the basis of a current flowing in the primary side of the power supply circuit. SOLUTION: The power supply circuit 31 includes a transformer 37, in which a voltage converted from a DC current into an AC current by MOSFETs 32-35 is applied to a primary-side coil 37-1, diodes 39, 40 for rectifying output of the transformer 37, and a coil 41 and a capacitor 42 for smoothing the rectified voltage. A control circuit 1 controls each operation of the MOSFETs 32-35 so that an output voltage Vout of the power supply circuit becomes constant. When an output current Iout converted from a current flowing in the primary side exceeds a prescribed current Ir, the control circuit controls each operation of the MOSFETs 32-35 such that the output voltage Vout is reduced in response to an increase of an addition result between the output current Iout and a correction value based on the output voltage Vout. COPYRIGHT: (C)2009,JPO&INPIT
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