| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a power factor improving circuit which can achieve higher efficiency in full load range, without enlarging the circuit scale, in a switching power source. <P>SOLUTION: A multiplier 113 integrates voltage MULT which is obtained by dividing input voltage and voltage which is obtained via a comparator 117 from the voltage MO being obtained by dividing the output voltage. A comparator 112 compares the voltage CS geared to the current flowing to a MOS-FETQ1 with the multiplication results of the multiplier 113. An RS flip flop 115 takes a set reset action, based on the voltage which is obtained via a comparator 116 from the signal z/c signal outputted from the auxiliary winding Nc of the transformer T1 and the comparison results in the comparator 112, and performs the ON/OFF control of the MOS-FETQ1 via a driver 111. An OFF setting circuit 118 selects a current critical action or a current continuous action, based on the output voltage VGS and the z/c signal via an OSMV120. <P>COPYRIGHT: (C)2007,JPO&INPIT |
