Boost DC-DC converter with charge-recycling (CR) and fast reference tracking (FRT) techniques for high-efficiency and low-cost LED driver

A charge-recycling (CR) technique and fast reference tracking (DRT) are proposed for implementing a high efficiency and low cost RGB backlight module in color sequential notebook computerspsila display. A RGB LED driver composed of an asynchronous 1.5 MHz DC/DC boost converter with FRT and CR techniques was fabricated in TSMC 0.25 mum BCD 40 V to generate 17 V for 6-series red LEDs or 21 V for 6-series green, or blue LEDs. The CR technique stores extra energy at the output node when the output voltage is switched from low to high voltage level and releases the reserved energy back to the output node at next period. Furthermore, the output voltage can be rapidly switched between two different voltage levels by FRT technique without wasting much power owing to the CR technique.