Patent ID: 7995363

Claim:
A DC-DC converter comprising: a charge pump unit that precharges a boost node in response to a precharge clock pulse and boosts the boost node to a boosted voltage in response to a pump clock pulse; a clock pulse generator unit that generates the precharge clock pulse and the pump clock pulse in which corresponding pulse widths increase over time during a plurality of time intervals; and a pulse-width controller that outputs a plurality of pulse-width control signals for shortening turn-on times of the precharge clock pulse and the pump clock pulse at an initial operation time, and lengthening the turn-on times by the pulse widths for corresponding durations of the time intervals, after storing the pulse widths and corresponding durations according to the time intervals, wherein the charge pump unit comprises: a plurality of first switches that precharge a first node and a second node to a first voltage by connecting the first and second nodes, and precharge a third node to a second voltage, in response to the precharge clock pulse; a plurality of second switches that connect the first and third nodes, and that connect the second node to a fourth node, in response to the pump clock pulse in the charge pumping operation; a first pump capacitor, connected between the first node and the third node, that performs a charge pumping operation for the first node and the second node precharged to the first voltage, in response to the pump clock pulse; and a second pump capacitor, connected between the fourth node and the second voltage, that outputs the boosted voltage by receiving a pumped voltage of the second node through the fourth node precharged to the second voltage when the plurality of second switches are turned on, and wherein the clock pulse generator unit comprises: a plurality of pulse generators that generate and selectively output precharge clock pulses and pump clock pulses having pulse widths increasing according to the plurality of time intervals, in response to the plurality of pulse-width control signals, based on a clock signal.