A highly efficient switched-capacitor LED driver with switching frequency hopping technique

Author

Yin, Liang ; Wu, Xiaobo ; Zhao, Menglian

Author_Institution

Inst. of VLSI Design, Zhejiang Univ., Hangzhou, China

fYear

2010

Firstpage

521

Lastpage

523

Abstract

A novel frequency hopping technique is proposed to increase the efficiency in a switched-capacitor LED driver, based on analyzing the dependence of power loss on switching frequency. LEDs´ load current is featured uniquely by jumping periodically from a constant value (20mA) to zero for dimming function. Developed on an improved VCO, the hopping technique makes the switching frequency vary discretely at pre-defined levels in accordance with load current, whose basic principle is that heavier the load, higher the frequency (200KHz to 1MHz). By elimination of current-sensing resistors and other optimization measures, the efficiency is further improved. The circuit is designed and simulated in TSMC 0.35μm CMOS process. Simulation results show the overall efficiency is increased by 5% on average in comparison with fixed high frequency ones.

Keywords

CMOS integrated circuits; driver circuits; light emitting diodes; switched capacitor networks; voltage-controlled oscillators; CMOS process; VCO; current-sensing resistors; dimming function; frequency 200 kHz to 1 MHz; optimization measures; power loss; size 0.35 mum; switched-capacitor LED driver; switching frequency hopping technique; Converters; Light emitting diodes; Pulse width modulation; Resistors; Switches; Switching frequency; Switching loss;

fLanguage

English

Publisher

ieee

Conference_Titel

Solid-State and Integrated Circuit Technology (ICSICT), 2010 10th IEEE International Conference on

Conference_Location

Shanghai

Print_ISBN

978-1-4244-5797-7

Type

conf

DOI

10.1109/ICSICT.2010.5667352

Filename

5667352