A low-cost method for minimizing the chromaticity shift of dc-driven phosphor-converted white LEDs by thermal design

Ka Hong Loo, Y. M. Lai, Chi Kong Tse

Research output: Chapter in book / Conference proceedingConference article published in proceeding or bookAcademic researchpeer-review

2 Citations (Scopus)

Abstract

Most commercial white LEDs are made from blue LEDs coated with YAG phosphor. They generally produce emission spectra that shift in opposite directions under the influences of current amplitude and junction temperature changes. By using a commercial white LED sample, LUXEON K2, the effects of current amplitude and junction temperature on the chromaticity shift of white LEDs over dimming, during which both parameters are known to assert their influences simultaneously, are studied experimentally. The impact of driving/dimming by dc current is discussed through a graphical analysis and verified by experimental measurement. Due to the counteracting influences of current amplitude and junction temperature changes, driving/dimming white LEDs by dc current offers a more superior chromaticity stability compared to PWM. By means of selection of a heat sink's thermal resistance estimated from an analytical equation derived in this paper, it is found that the overall chromaticity shift of white LEDs over dimming can be minimized at low cost.
Original languageEnglish
Title of host publication8th International Conference on Power Electronics - ECCE Asia
Subtitle of host publication"Green World with Power Electronics", ICPE 2011-ECCE Asia
Pages515-519
Number of pages5
DOIs
Publication statusPublished - 31 Aug 2011
Event8th International Conference on Power Electronics - ECCE Asia: "Green World with Power Electronics", ICPE 2011-ECCE Asia - Jeju, Korea, Republic of
Duration: 30 May 20113 Jun 2011

Conference

Conference8th International Conference on Power Electronics - ECCE Asia: "Green World with Power Electronics", ICPE 2011-ECCE Asia
CountryKorea, Republic of
CityJeju
Period30/05/113/06/11

Keywords

  • AM driving
  • chromaticity shift
  • color stability
  • thermal design
  • White LED

ASJC Scopus subject areas

  • Electrical and Electronic Engineering

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