| 摘要 |
PROBLEM TO BE SOLVED: To provide a converter for controlling an output voltage steadily in accordance with input voltages in a wide range and load variations. SOLUTION: The converter includes a primary side drive circuit 20 with a high frequency switching, a voltage transformer 30 driven by the switching, an output rectifying circuit 40 connected on the secondary side, a detection circuit 50 for detecting the output voltage thereof, a control type judgment circuit 60 for carrying out frequency modulation or time-ratio modulation according to the detection signal, a frequency modulation circuit 90 for determining the operation frequency or the time ratio of the primary side drive circuit 20 according to the judgment signal or a control type switch circuit 80 for switching the operation of a time ratio modulation circuit 100, and a time ratio limiting circuit 70 for changing into a frequency modulation method and carrying out a time ratio limiting.
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