Digital to analog convert and driving method for display device

A digital-to-analog converter (DAC) includes a decoder unit for receiving an external digital data signal operating over a first predefined voltage range (i.e., 0-5V); a resistor array for generating a plurality of gray voltages defined across a second voltage range that is substantially wider than the first predefined voltage range, and a voltage selecting unit for selecting one of the gray voltages based on an output of the decoder unit, wherein the decoder unit includes a plurality of decoder stages and first and second boost circuits for generating output signals operating over a third voltage range (i.e., 0-7V) that is substantially wider than the first predefined voltage range while not requiring an additional power supply for producing voltages of the third voltage range (i.e., 0-7V).