Disclosed are a power supplying apparatus, a backlight assembly and an LCD apparatus having the same. A control section outputs a switching signal so as to control an output of a constant current supplied to a lamp unit in response to on and/or off signals and a dimming signal and a switching section controls an output of a direct current voltage source in response to the switching signal. A power outputting section provides an alternating current voltage source having a constant voltage to the lamp unit. A sensing section senses variation of a power supplied to the lamp unit and a detecting section compares a sensing signal with a predetermined reference signal to output a detecting signal to the control section, thereby maintaining the constant current to be supplied to the lamp unit. Accordingly, the LCD apparatus may prevent deterioration of an image and damage of circuit thereof.