A flat panel display device, LCD controller and associated method is provided. The flat panel display device includes a display panel, a lamp for providing a backlight source for the display panel, a power transformation module for providing a power source for the lamp, a non-volatile storage unit for storing program code, and a display controller. The display controller includes an image processing module for processing image data and outputting processed results to the display panel, and a digital pulse width modulation module for adjusting on and off time of the power transformation module with reference to a synchronization signal.