A digital driving system for a display includes a scan driver adapted to supply scan signals serially to scan lines of the display, a data driver adapted to supply a first data signal and a second data signal to data lines of the display, a timing controller adapted to control the scan driver and the data driver in accordance with a main clock, and to supply external data to the data driver, and a vertical synchronizing signal synchronizing circuit adapted to synchronize an internal vertical synchronizing signal and an external vertical synchronizing signal.