A mobile terminal, comprising: a display panel in which pixel arrays include pixels disposed in a matrix form according to an intersection structure of data lines (DL) and gate lines (GL), the pixel arrays divided into a main display unit and an auxiliary display unit both on a common substrate; a display driver; a mobile industry processor interface, hereinafter referred to as MIPI; and a host system configured to transmit data of an input image and watch data to the display driver through the MIPI, wherein the display driver comprising: a data driver configured to supply a data voltage to the data lines (DL); a first gate driver connected to gate lines (GL) of the main display unit; and a second gate driver connected to gate lines (GL) of the auxiliary display unit, wherein, in a full display mode, the first gate driver is configured to supply gate pulses to the gate lines (GL) of the main display unit and the second gate driver is configured to supply gate pulses to the gate lines (GL) of the auxiliary display unit, wherein the gate pulses are pulses alternating between a gate high voltage (VGH) and a gate low voltage (VGL); and in an always-on mode, the first gate driver is configured to fix a voltage of the gate lines (GL) of the main display unit to the gate low voltage (VGL) less than a ground voltage (GND), wherein the ground voltage (GND) is equal to 0 V, and the second gate driver is configured to supply the gate pulses to the gate lines (GL) of the auxiliary display unit, wherein the auxiliary display unit is configured to display data in the full display mode and the always-on mode, and the main display unit is configured to stop operation in the always-on mode; wherein the mobile terminal comprises a DC-DC converter configured to generate the gate high voltage (VGH) to be greater than or equal to a threshold voltage of TFTs formed in the pixel array, and configured to generate the gate low voltage (VGL) to be less than the threshold voltage of the TFTs, wherein the gate low voltage (VGL) is less than the ground voltage (GND) and the ground voltage (GND) is less than the gate high voltage (VGH); wherein the data driver is configured to, in the full display mode, receive watch data corresponding to a clock image to be displayed on the auxiliary display unit through the MIPI; wherein the data driver is configured to, in the always-on mode, generate watch data for display by the auxiliary display unit , rather than using watch data communicated through the MIPI; wherein the data driver comprises an internal data generating unit configured to generate watch data corresponding to the clock image to be displayed on the auxiliary display unit without communication between the host system and the display driver through the MIPI in the always-on mode, and wherein the internal data generating unit comprises a counter memory and a font memory, and the internal data generating unit is configured to generate the watch data with font data read from the font memory, and configured to update the watch data by counting a clock received from the host system ; wherein the data driver is configured to display the watch data generated by the internal data generating unit on the auxiliary display unit in the always-on mode. <EOS>