A driving device for a display and a display using same, and a driving method of the display are provided. The display includes a display panel on which an image is displayed, and at least one optical sensor (photodetector) to detect the intensity of ambient (external) light incident upon the display panel. An external-brightness detector outputs an external-brightness signal based on the intensity of external (ambient) light and a backlight brightness controller changes the brightness of the image displayed (or backlight) on the display panel according to the external-brightness signal. The driving device may be implemented on an integrated circuit adapted to be connected to external-light photodetectors of type 1 or of type 2. The driving device may be may be dynamically configured to generate the external-brightness signal by sensing a voltage level of the light detecting node in a first mode of operation and may be reconfigured to generate the external-brightness signal by sensing a current level of the light detecting node in a second mode.