Patent ID: 7348766

Claim:
A switching power supply device comprising: a first source voltage supply arrangement operable to supply a first supply voltage; a PWM signal generator operable to generate a PWM signal; a first switching arrangement operable to switch the first supply voltage based on the PWM signal; a converter operable to convert the switched first supply voltage to a second supply voltage; a difference signal detector operable to output the difference between the second supply voltage and a predetermined reference voltage as a difference signal; an intermittent controller operable to stop the switching operation of the first switching arrangement when the difference signal is less than or equal to a first threshold value; a current converter operable to convert the difference signal to a current signal; and a voltage converter operable to convert the current-converted difference signal to a voltage signal; wherein the PWM signal generator varies the pulse width of the PWM signal based on the voltage-converted difference signal and generates the PWM signal.