SWITCHING POWER SUPPLY DEVICE

摘要

PROBLEM TO BE SOLVED: To suppress downward fluctuation in the output voltage Vout of a secondary-side rectifying and smoothing unit 4 immediately after synchronous rectifiers 5 and 6 start to turn on during a period in which soft start is carried out to gradually increase the output voltage Vout when the power is turned on. SOLUTION: An inductance circuit 9 is constituted as a variable inductance circuit whose inductance value is increased when the energization current of the circuit 9 becomes smaller than a preset value. The inductance circuit 9 has a sufficiently small inductance value to avoid saturation during normal operation. When the energization current is small, the inductance value is varied to a sufficiently large value to suppress downward fluctuation in the output voltage Vout. COPYRIGHT: (C)2004,JPO&NCIPI