| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a power-factor improvement circuit capable of keeping an output voltage at a high value for a long time even if the capacity of an output capacitor is small. <P>SOLUTION: During a low input, MOSFET23 turns on and MOSFET21 turns off. When a drive voltage from a PFC control unit 11 is at a high level, MOSFET7 turns on and a voltage is induced in a secondary winding 25b, so that an input current Iin flows through a choke coil 6 and excited energy is stored. When a drive voltage is at a low level, MOSFET7 turns off and MOSFET24 turns on. The excited energy in the choke coil 6 is discharged in superposition with the output capacitor 9b, by which an output capacitor 9a is charged at a higher voltage than an input voltage Vi and the voltage is output from output terminals 12, 13. <P>COPYRIGHT: (C)2006,JPO&NCIPI |
