Switched-mode power supply using variable bias current

摘要

There is provided a switched-mode power supply including: a PWM control unit generating a clock signal having pulse widths of the clock depending on a load to provide a path switching signal; a clock counter counting the clock signal to generate a control signal; a current source generating a current; a current mirroring circuit unit having a plurality of upper side current mirroring units respectively mirroring the current from the current source to create a current having a predetermined amplitude; a first current adjusting unit individually selecting a portion of the plurality of upper side current mirroring units according to the control signal; and a path switching circuit unit switched according to the path switching signal so as to select a charging path between the first current adjusting unit and a power switch or a discharging path between the power switch and the ground.

主权项

1. A switched-mode power supply comprising:
a pulse width modulation (PWM) control unit generating a predetermined clock signal and varying pulse widths of the clock signal depending on a load to provide a path switching signal; a clock counter counting the clock signal to generate a control signal; a current source generating a predetermined current; a current mirroring circuit unit connected to a first operating voltage terminal, and having a plurality of upper side current mirroring units respectively mirroring the current from the current source to create a current having a predetermined amplitude; a first current adjusting unit individually selecting a portion of the plurality of upper side current mirroring units according to the control signal; and a path switching circuit unit switched according to the path switching signal so as to select a charging path between the first current adjusting unit and a power switch or a discharging path between the power switch and the ground.