A display device of the present invention includes a display driving integrated circuit and an application processor. The display driving integrated circuit provides an internal synchronization signal based on an internal clock signal. The application processor calculates a time offset which is a differential between an actual time and the internal synchronization signal based on the synchronization signal, and provides the calculated time offset to the display driving integrated circuit. The display driving integrated circuit independently calculates a display time in its own time display mode based on the time offset and an actual time provided by the application processor, and displays the calculated time on a display panel.
