An Improved LCLC Current-Source-Output Multistring LED Driver With Capacitive Current Balancing

Xiaohui Qu, Siu Chung Wong, Chi Kong Tse

Research output: Journal article publicationJournal articleAcademic researchpeer-review

78 Citations (Scopus)


Passive or active current balancing circuits are usually used to mitigate current imbalance in driving multiple light-emitting-diode (LED) strings. Passive current balancing schemes adopting capacitors with high reliability, small size and low cost are very popular in many applications. However, the high reactive power of the capacitive balancing scheme with variable frequency control will bring high power stress on the VA rating of the main switches which drive this passive current balancing circuit and decrease the overall efficiency. Fixed frequency control does not permit zero-voltage switching (ZVS) under load variations. Hence, this paper proposes a current-source-output LED driver based on LCLC resonant circuit to provide a constant output current regardless of variations in LED parameters. In the LCLC circuit, the number of additional capacitors is scalable with the number of LED strings for current balancing. Moreover, the input impedance of the improved LCLC circuit is designed to be resistive at the operating frequency to minimize reactive power. The conventional duty cycle control can easily incorporate ZVS. The analysis, implementation and verification are detailed in this paper.
Original languageEnglish
Pages (from-to)5783-5791
Number of pages9
JournalIEEE Transactions on Power Electronics
Issue number10
Publication statusPublished - 1 Oct 2015


  • constant current source
  • current balancing
  • LED driver
  • passive circuit

ASJC Scopus subject areas

  • Electrical and Electronic Engineering


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