SWITCHING MODE POWER SUPPLY USING VARIABLE BIAS RESISTOR

摘要

The present invention relates to a switching mode power supply comprising: a PWM control unit which generates a predetermined clock and provides a path switch signal by varying the pulse width of the clock according to loads; a clock counter which generates a control signal by counting the clock; a variable current source which generates a current determined according to predetermined constant voltage and adjustable resistance and varies the adjustable resistance according to the control signal; a current mirror circuit unit which is connected to an operating voltage terminal to mirror the current of the variable current source into a predetermined size; and a path switch circuit unit which is switched according to the path switch signal to connect a charging path between the current mirror circuit unit and a power switch or a discharging path between the power switch and a ground.