Patent ID: 7285941

Claim:
A DC-DC converter to convert a DC power input from an external source into a predetermined DC power required for an electric load and supply the converted DC power to the electric load, the DC-DC converter comprising: a switch part in which each of a pair of switches connected in series is connected with at least one switch in parallel and that cuts or supplies the input DC power to the electric load; a current sensor to sense a load current flowing through the electric load; and a controller to control the switch part changing a number of the switches to be enabled to cut or supply the DC power to the electric load, according to an intensity of the load current sensed by the current sensor, wherein the controller generates a PWM signal to drive the switches and selectively supplies the PWM signal to the switches to change the number of the switches to be enabled according to the intensity of the load current, and the controller comprises: a PWM controller to generate the PWM signal and enable/disable signals to enable/disable the switches according the intensity of the load current; a PWM signal line to transfer the PWM signal generated from the PWM controller to a first predetermined number of switches; and at least one logic operator to logically operate the PWM signal and the enable/disable signals generated by the PWM controller and to output the operated result to a second predetermined number of the switches.