In a method of driving a light source, light generated by a light source is sensed in order to detect color coordinates of a red color, color coordinates of a green color and color coordinates of a blue color. A light source color space formed by the color coordinates of the red, green and blue colors is compared with a reference color space formed by red reference color coordinates, green reference color coordinates and blue reference color coordinates. Then, color temperature of the light generated by the light source is controlled so that the light source color space covers the reference color space.