Title :
An adaptive on-time controlled boost LED driver with high dimming ratio
Author :
Liu, Sheng ; Wu, Xiaobo ; Yuan, Fenjie ; Zhao, Menglian
Author_Institution :
Inst. of VLSI Design, Zhe Jiang Univ., Hangzhou, China
Abstract :
A high efficiency high dimming ratio boost LED driver without color shift issue is presented in this paper. The boost converter is controlled by an adaptive on-time (AOT) controller, using improved control stratagem based on constant on-time (COT) control, so as to realize fast transient response to achieve high dimming ratio. With AOT control, the operation frequency maintains constant under continuous current mode (CCM) and the output voltage ripple could be reduced. In addition, Pulse frequency modulation (PFM) is implemented automatically under discontinuous current mode (DCM) to improve the system efficiency. The chip was designed and implemented in 1.5 μm bipolar-CMOS-DMOS (BCD) process. The simulation and experimental results showed that the minimum dimming on-time could be reduced to 1.2 μs, which means a dimming ratio of 2000:1 is available at dimming frequency of 400 Hz.
Keywords :
CMOS integrated circuits; adaptive control; driver circuits; light emitting diodes; pulse frequency modulation; AOT controller; BCD process; CCM; COT control; DCM; PFM; adaptive on-time controlled boost LED driver; bipolar-CMOS-DMOS process; constant on-time control; continuous current mode; discontinuous current mode; frequency 400 Hz; high efficiency high dimming ratio boost LED driver; improved control strategy; output voltage ripple; pulse frequency modulation; size 1.5 mum; time 1.2 mus; transient response; Adaptive On-Time; Boost; High Dimming Ratio; LED Driver; PWM Dimming;
Conference_Titel :
IECON 2012 - 38th Annual Conference on IEEE Industrial Electronics Society
Conference_Location :
Montreal, QC
Print_ISBN :
978-1-4673-2419-9
Electronic_ISBN :
1553-572X
DOI :
10.1109/IECON.2012.6388806
