Patent ID: 7279870

Claim:
A DC-DC converter for converting an input voltage to an output voltage, the DC-DC converter comprising: a first output transistor for receiving the input voltage; a second output transistor connected in series to the first output transistor; and a control unit for generating a drive signal that controls activation and inactivation of the first output transistor and the second transistor and for providing the first output transistor and the second transistor with the drive signal, the control unit changing duty of the drive signal in accordance with the output voltage, the control unit including: a plurality of resistors for generating a divided voltage from the output voltage; an error amplifier for comparing the divided voltage with a reference voltage to generate an error signal; an offset circuit for changing voltage of the error signal by an offset voltage that is in accordance with a control signal to generate an offset signal; a PWM comparator for comparing the offset signal with a triangular wave signal and generating the drive signal to have a duty that is in accordance with the comparison result; and an offset controller, connected to the offset circuit, for comparing the output voltage and the input voltage and generating the control signal in accordance with the comparison result.