In a display apparatus having a backlight unit, a light unit includes plural light source strings commonly connected to an output terminal of a boosting circuit to generate light in response to a light source driving voltage. The light source strings are grouped into plural light generating groups. Plural driving circuits are respectively connected to the light generating groups, and each driving circuit sequentially outputs feedback voltages from the light source strings of a corresponding light generating group. A minimum voltage detecting circuit compares the feedback voltages with each other from the driving circuits to detect a minimum voltage and outputs a control signal according to the detected minimum voltage. A voltage control circuit controls a voltage level of the light source driving voltage in response to the control signal. Accordingly, although the number of the driving circuits increases, power consumption used in each driving circuit may be reduced.