Voltage converting circuit and method

A voltage converting circuit for converting an input voltage into an output voltage, the voltage converting circuit comprising:

• a switching unit switched on and off alternately to adjust an input current corresponding to the input voltage to regulate the output voltage;
• a modulation signal generator receiving a feedback signal corresponding to the output voltage to generate a pulse width modulation (PWM) signal when the output voltage is different from a target voltage;
• a comparator receiving and comparing the feedback signal with a reference signal to generate a comparing signal when the output voltage is different from the target voltage;
• and
• a logic unit for performing a logical conjunction of the PWM signal and the comparing signal to generate a control signal for alternately switching on and off the switching unit.

A method for converting an input voltage into an output voltage, comprising:

• generating a feedback signal corresponding to the output voltage;
• generating a pulse width modulation (PWM) signal according to the feedback signal;
• comparing the feedback signal with a reference signal to generate a comparing signal;
• performing a logical conjunction of the PWM signal and the comparing signal to generate a control signal;
• and
• alternately switching on and off a switching unit with the control signal to adjust an input current corresponding to the input voltage to regulate the output voltage.