| 摘要 |
A power factor correction circuit is provided to compensate for the distortion of the input current by using the second coil voltage or by directly sensing the input voltage and by differently setting up the turn-on period of the switch according to the input voltage. The power factor correction circuit is prepared. The second coil (Naux) is coupled with the first inductor. The second coil voltage is inducted by the first inductor. The output voltage of the output terminal of the second coil voltage and the power factor correction circuit are input. Then the current flowing in the first inductor becomes from the positive to the zero. At this time the switch the turn on with the second coil voltage. If the switch is turned on, the first control voltage corresponding to the output voltage is controlled according to the second coil voltage and the second control voltage is produced. The switching controller compares the second control voltage with the reference voltage and performs the control turning the switch off.
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