Output voltage adjustable dc-dc conversion circuit

The present invention provides a DC-DC converter circuit, comprising a DC power, a DC-DC converter, a power management chip and a load, wherein the load may be a backlight of the liquid crystal display. The power management chip controls the DC-DC converter converts the DC voltage of the DC power supplied into an output voltage to supply the load, and according to the minimum voltage variation of the actual load required for controlling the DC to DC converter to adjust its output voltage the actual output voltage reaches the minimum voltage required by the load.