| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a power factor improving circuit which can output an abnormal signal to a load circuit when a fault occurs and the circuit is stopped, and to provide a switching power supply which can improve safety. <P>SOLUTION: The power factor improving circuit includes a control circuit 20 for turning on/off a switching element Q1 based on an output voltage by inputting the output voltage from a voltage detecting element a; detection holding means 23, 24 for stopping the switching element by detecting the fault, if the fault occurs in the power factor improving circuit, holding a stop state and outputting a holding signal; an abnormal operation signal output means 30 for outputting the voltage of a predetermined voltage or higher as an abnormal operation signal to the voltage detecting terminal a based on the holding signal from the detection holding means 23, 24; and an abnormal signal detecting means 40 for detecting that the voltage detecting element a becomes the voltage of the predetermined voltage or higher based on the abnormal operation signal from the abnormal operation signal output means 30 and outputting the abnormal signal to the load circuit 10. <P>COPYRIGHT: (C)2006,JPO&NCIPI |
