Patent ID: 8373397

Claim:
A DC-DC converter configured to turn off at least an unnecessary circuit part of the DC-DC converter when operating in a light load mode, the DC-DC converter comprising: a first MOS transistor connected at a first terminal to a power supply and connected at a second terminal to a first node; a second MOS transistor connected at a first terminal to the first node and connected at a second terminal to ground; a coil connected at a first terminal to the first node and connected at a second terminal to an output terminal; a capacitor connected at a first terminal to the second terminal of the coil and connected at a second terminal to ground; a voltage divider configured to divide a voltage at the output terminal and to output the divided voltage; an error amplifier configured to receive the divided voltage and a reference voltage, wherein the error amplifier is configured to output a voltage based on comparison of a reference voltage to the divided voltage; a filter connected at a first terminal to the output of the error amplifier and connected at a second terminal to ground, wherein the filter is configured to compensate for a phase of the voltage signal output by the error amplifier; a control circuit configured to turn the first MOS transistor and the second MOS transistor on and off in a complementary manner by outputting control signals to gates of the first MOS transistor and the second MOS transistor, the control signals being pulse signals; a mode comparator configured to receive the voltage output from the error amplifier and a threshold voltage, wherein the mode comparator is configured to output a normal mode signal when the voltage output from the error amplifier is greater than the threshold voltage, and to output a light load mode signal when the voltage output from the error amplifier is less than the threshold voltage; and an assisting circuit configured to assist boosting of the voltage output from the error amplifier when the output signal of the mode comparator changes from the light load mode signal to the normal mode signal.