Patent ID: 6815939
Filing Date: 2004-11-09
Classification: H02M,H03F,Y02B

Abstract:
A switching power supply unit, comprising:a switching circuit for switching on and off an input voltage in response to an instruction signal received; a smoothing coil connected to the output end of said switching circuit for smoothing the switching output of said switching circuit; an output condenser connected to the output end of said smoothing coil and charged to the output voltage of said power supply unit, a pulse signal generator for generating a periodic pulse signal having a duty factor in accord with the difference between a reference voltage and a feedback voltage associated with said output voltage; and a delay-control unit receiving said pulse signal from said pulse signal generator and a light-load determination signal indicating whether the load connected to the switching power supply unit is light or not to output as said pulse signal said instruction signal as it is when said load is not light, but otherwise output said pulse signal after widening the pulse width thereof.