Provided are a display device and a method of controlling a power integrated circuit (PIC) thereof. The display device in one embodiment includes a controller for generating a switch pulse signal synchronized with an input image and initializing the switch pulse signal during a frame blank period in which the input image is not present; and a power integrated circuit (PIC) driven according to the switch pulse signal to generate power of a display panel. A duty ratio of the switch pulse signal is aligned to be greater than 0 and equal to or less than 3% during an alignment period set within a frame blank period, compared with a normal period. Thus, a change in the duty ratio of the switch pulse signal within the frame blank period is controlled to be minimized to prevent a degradation of image quality due to the variation of power.