A data driver includes a ramp signal generator generating a first ramp signal and a second ramp signal, a counter generating a count signal based on a clock signal, and channels each generating a data signal based on the first ramp signal, the second ramp signal, and the count signal. Each channel includes a latch circuit dividing the image data into a first partial data and a second partial data and latching the first and the second partial data, a duplication driver generating first and second reference signals by duplicating the first and second ramp signals, a digital-analog converter generating a driving signal corresponding to a first partial data based on the first and second reference signals, and an output circuit sampling the driving signal by comparing the second partial data with the count signal to output the data signal.