Patent ID: 8330442

Claim:
A direct current (DC) to DC converter comprising: a control circuit receiving and comparing a DC output voltage, wherein when the DC output voltage lower than a first threshold voltage, the control circuit outputs a pulse width modulation (PWM) signal with a first frequency, when the DC output voltage higher than the first threshold voltage, the control circuit outputs the PWM signal with a second frequency, and the second frequency is higher than the first frequency, the control circuit comprises: an error amplifier receiving the DC output voltage and a reference voltage for generating a compensation signal; a comparator receiving the first threshold voltage and the DC output voltage, wherein when the DC output voltage is lower than the first threshold voltage, the comparator outputs a first level signal, and when the DC output voltage is higher than the first threshold voltage, the comparator outputs a second level signal; a signal generator connected to the comparator, wherein when the comparator outputs the first level signal, the signal generator outputs a wave signal with the first frequency, and when the comparator outputs the second level signal, the signal generator outputs the wave signal with the second frequency; and a modulator receiving the compensation signal and the wave signal to generate the PWM signal; a gate driver circuit receiving the PWM signal and converting the PWM signal to a first driving signal and a second driving signal; and a power stage circuit converting a DC input voltage to the DC output voltage according to the first driving signal and the second driving signal.