High efficiency and/or low cost LED backlight system for color sequential technique in color filter-less LCD system

This paper proposes a design methodology for implementing a high efficiency and/or a low cost RGB backlight module in color sequential notebook computers' display. A RGB LED driver composed of an asynchronous 1.5MHz DC/DC boost converter with dual loop control is fabricated by TSMC 0.25 mu m BCD 40V to generate 17V or 21V output voltage to turn on more than 6 series-red, 6 series-green, or series-blue LEDs at the same time for the notebooks' backlight. Besides, charge-recycling technique is used to restore extra energy at the output node when switching to different forwarding light emitting diodes (LEDS) and release the energy new time. The total power consumption of a 15.4' LCD panel of a notebook computer can be reduced from 5W to about 2-3 W.