A DC-DC converter including a first power supply including a first converter outputting a first power voltage, a first sensor detecting a panel current from an output of the first converter; and a first output group including a plurality of inverting converters outputting a second power voltage based on the panel current; a second power supply including a second converter outputting the first power voltage, and a second output group including a plurality of inverting converters outputting the second power voltage based on the panel current; and a first phase controller controlling operations of the inverting converters included in each of the first and second output groups based on the detected panel current. The second power supply operates when the panel current exceeds a predetermined enable value.