DRIVING DEVICE, DISPLAY DEVICE having the same and DRIVING MATHOD of the same

The present invention relates to a drive device for a display device including a plurality of pixels that are connected to data lines, a gradation voltage generating unit for generating a plurality of gray voltages, a voltage selector selecting an output voltage from the gray voltages, the voltage selection unit changing the level of the output voltage the voltage level conversion unit is applied to the data line, the voltage level converting units the voltage selection unit and a first switching unit for connecting the data line, and directly connected to the data line and the voltage selector claim and including a second switching, operates the first switching unit and the second switching unit at different times. Therefore, when charging or discharging the data voltage to the data line, and does not use such a separate discharging transistor or discharging amplifier, while reducing the power consumption, it is possible to reduce the area of ​​the data driver. A liquid crystal display device, a data driver, the output buffer, the data line, the transistors