Patent ID: 7800354
Filing Date: 2010-09-21
Classification: H02M,Y02B

Abstract:
1. A switching power supply comprising: rectifying means for rectifying an AC power supply; boosting means including a switching device for boosting an output of the rectifying means; smoothing means for smoothing an output of the boosting means; first voltage detecting means for detecting a voltage between main terminals of the switching device as a voltage obtained by dividing the voltage between the main terminals; selecting means for selecting only the voltage by which the switching device is in an on-state among voltages detected by the first voltage detecting means, and setting voltages other than the selected voltage to a GND potential; amplifying means for amplifying the voltage selected by the selecting means and outputting the same as a current corresponding value of a current to flow in the switching device; second voltage detecting means for detecting an output voltage of the smoothing means; and driving means which form a pulse signal based on the current corresponding value and the output voltage, for driving the switching device by the pulse signal, wherein a GND potential of a control circuit that includes the selecting means, the amplifying means, and the driving means is the same potential as a low potential side of the switching device.