SAR-Controlled Adaptive Off-Time Technique Without Sensing Resistor for Achieving High Efficiency and Accuracy LED Lighting System

Author

Liu, Chao-Hsuan ; Hsieh, Chun-Yu ; Hsieh, Yu-Chiao ; Tai, Ting-Jung ; Chen, Ke-Horng

Author_Institution

Dept. of Electr. & Control Eng., Nat. Chiao Tung Univ., Hsinchu, Taiwan

Volume

57

Issue

6

fYear

2010

fDate

6/1/2010 12:00:00 AM

Firstpage

1384

Lastpage

1394

Abstract

A successive approximation register (SAR) is utilized to control adaptive off-time in order to regulate accurate light-emitting diode (LED) current and improve efficiency of LED driver. The proposed SAR-controlled adaptive off-time technique without the external sensing resistor can sense the current flowing through LEDs during the turning on of the N-type power MOSFET, as well as provide adaptive off-time depending on the input voltage and the numbers of LED, to obtain an accurate LED current. Experimental results show the inductor current ripple is kept within ±15% of the DC current. As a result, line regulation is guaranteed in this proposed design.

Keywords

light emitting diodes; power MOSFET; LED lghting system; N-type power MOSFET; SAR; controlled adaptive off-time technique; successive approximation register; Adaptive off-time; hysteretic current control (HCC); on-chip low-side current sensing; peak current control (PCC); pulsewidth modulation (PWM) dimming; successive approximation register (SAR);

fLanguage

English

Journal_Title

Circuits and Systems I: Regular Papers, IEEE Transactions on

Publisher

ieee

ISSN

1549-8328

Type

jour

DOI

10.1109/TCSI.2009.2028643

Filename

5356207