SEMICONDUCTOR INTEGRATED CIRCUITS

Improvements in performance and reliability for segmented linear LED drivers

Cong Liu1, 2, , Xinquan Lai1, 2 and Hanxiao Du1, 2

+ Author Affiliations

 Corresponding author: Liu Cong, Email: liucong4213@163.com

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Abstract: Several improvements have been made to the conventional segmented linear light-emitting diode (LED) driver topology to enhance the performance and reliability of the system. A compensation technology is proposed to adaptively adjust the impedance of the sensing circuit to keep the output luminance constant in case of line voltage variations. Based on the proposed technology, an active over temperature protection technique is presented to constrain the averaged LED current according to the junction temperature to prevent the driving IC from overheating. Otherwise, a pulse width modulation dimming circuitry which is compatible with input logic level ranging from 1.8 to 20 V is proposed. The proposed technologies are implemented in a 1.0 μm 5/20/500 V BCD technology with three high voltage MOSFETs integrated on chip. The experimental results show that within 220±15% V, 50 Hz AC line-voltage variation, the output luminance is restrained to 4% in total. The output luminance can also be effectively controlled by the PWM dimming circuitry, and a dimming range of 95% is achieved with good linearity.

Key words: segment linear LED driverline regulationPWM dimmingactive OTP



[1]
[2]
[3]
[4]
[5]
[6]
[7]
Yu D J, Ning N, Wu S Y, et al. A high power factor AC LED driver with current glitch eliminated. Analog Integrated Circuits and Signal Processing, 2015
[8]
Kim J, Lee J, Park S. A soft self-commutating method using minimum control circuitry for multiple-string LED drivers. Proc IEEE ISSCC, 2013:367
[9]
Dayal R, Modepalli K, Parsa L. A direct AC LED driver with high power factor without the use of passive components. Proc IEEE ECCE, 2012:4230
[10]
[11]
[12]
Wang C, Xi J, He L. A linear constant current LED driver with no off-chip inductor or capacitor. Proc IEEE ISIE, 2014:2524
[13]
[14]
Park C, Rim C T. Filter-free AC direct LED driver with unity power factor and low input current THD using binary segmented switched LEDs rings and linear current regulator. Proc IEEE APEC, 2013:870
.  Functional block diagram of the proposed technology.

.  $I_{\rm LED}$ duty cycle drift due to AC line variation.

.  AC analysis of the proposed control loop. (a) Equivalent small signal model. (b) Bold diagram.

.  Proposed active OTP and PWM dimming circuitry.

.  Typical waveforms of the active OTP and PWM dimming technologies.

.  Photographs of the proposed IC and driving circuitry.

.  (Color online) Tested results for line compensation technology under different AC line-voltages. (a)) Input current waveforms. (b) Output luminance curve.

.  Experimental results of (a) active OTP and (b) PWM dimming technologies.

.   Performance summary and comparison

DownLoad: CSV
[1]
[2]
[3]
[4]
[5]
[6]
[7]
Yu D J, Ning N, Wu S Y, et al. A high power factor AC LED driver with current glitch eliminated. Analog Integrated Circuits and Signal Processing, 2015
[8]
Kim J, Lee J, Park S. A soft self-commutating method using minimum control circuitry for multiple-string LED drivers. Proc IEEE ISSCC, 2013:367
[9]
Dayal R, Modepalli K, Parsa L. A direct AC LED driver with high power factor without the use of passive components. Proc IEEE ECCE, 2012:4230
[10]
[11]
[12]
Wang C, Xi J, He L. A linear constant current LED driver with no off-chip inductor or capacitor. Proc IEEE ISIE, 2014:2524
[13]
[14]
Park C, Rim C T. Filter-free AC direct LED driver with unity power factor and low input current THD using binary segmented switched LEDs rings and linear current regulator. Proc IEEE APEC, 2013:870
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    Received: 26 October 2015 Revised: Online: Published: 01 July 2016

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      Cong Liu, Xinquan Lai, Hanxiao Du. Improvements in performance and reliability for segmented linear LED drivers[J]. Journal of Semiconductors, 2016, 37(7): 075004. doi: 10.1088/1674-4926/37/7/075004 C Liu, X Q Lai, H X Du. Improvements in performance and reliability for segmented linear LED drivers[J]. J. Semicond., 2016, 37(7): 075004. doi: 10.1088/1674-4926/37/7/075004.Export: BibTex EndNote
      Citation:
      Cong Liu, Xinquan Lai, Hanxiao Du. Improvements in performance and reliability for segmented linear LED drivers[J]. Journal of Semiconductors, 2016, 37(7): 075004. doi: 10.1088/1674-4926/37/7/075004

      C Liu, X Q Lai, H X Du. Improvements in performance and reliability for segmented linear LED drivers[J]. J. Semicond., 2016, 37(7): 075004. doi: 10.1088/1674-4926/37/7/075004.
      Export: BibTex EndNote

      Improvements in performance and reliability for segmented linear LED drivers

      doi: 10.1088/1674-4926/37/7/075004
      Funds:

      The authors thank Hui-Sen He and Long-Jie Zhong for their insightful contributions.

      More Information
      • Corresponding author: Liu Cong, Email: liucong4213@163.com
      • Received Date: 2015-10-26
      • Accepted Date: 2015-11-05
      • Published Date: 2016-07-25

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