US 2003/0201760 A1 · Switching power supply unit

Abstract

A switching power supply unit generates a pulse signal having a duty factor based on the voltage associated with the difference between a reference voltage and the output voltage of the unit, and the voltage associated with the current flowing through a smoothing coil. Upon receipt of the pulse signal and a light-load determination signal, a delay-control unit of the power supply unit outputs as an instruction signal supplied to the switching circuit the pulse signal as it is when the light-load determination signal indicates that the load is not light, but otherwise outputs the pulse signal after delaying and widening the pulse width thereof. Thus, when the load is light, the switching power supply unit may hold its switching frequency substantially low and constant without rendering the frequency bursting discontinuously.

Claims17

Dependent claims

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 said 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.

3 more elements

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 first 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 signal-thinning control unit receiving said first periodic pulse signal 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 instruction signal said first periodic pulse signal when said load is not light, but otherwise output a second periodic pulse signal that are generated by thinning said first periodic pulse signal.

3 more elements

Dependencies are inferred from the claim text.

Switching power supply unit

Life of this patent

Switching power supply unit

Life of this patent

Abstract

Claims17