On driving techniques for LEDs: Toward a generalized methodology

Ka Hong Loo, Wai Keung Lun, Siew Chong Tan, Y. M. Lai, Chi Kong Tse

Research output: Journal article publicationJournal articleAcademic researchpeer-review

110 Citations (Scopus)


LEDs must be externally driven by power sources to emit light. One problem associated with driving LEDs is its inherent nonlinear relation between the emission intensity and the forward current. Thus, the light output obtained from an LED is strongly dependent on the actual current waveforms employed to drive it. It is found that driving an LED with dc produces light output that surpasses all other techniques including the commonly used pulse-width modulation (PWM) technique. On the other hand, for dimming function, it is found that the PWM technique offers greater dimming flexibility in comparison to dc technique. In this paper, a generalized methodology for driving LEDs inheriting the features of both of these techniques is proposed. It employs a pulsating current switching between two discrete current levels, where the current levels and their durations can be concurrently varied for a more precise mapping of the driving conditions to the light output. The existing dc and PWM techniques can be viewed alternatively as being special cases of this more general approach.
Original languageEnglish
Article number5233853
Pages (from-to)2967-2976
Number of pages10
JournalIEEE Transactions on Power Electronics
Issue number12
Publication statusPublished - 1 Dec 2009


  • Bi-level driving
  • Dc
  • Diode I-V characteristic
  • High-brightness LED
  • Lighting system
  • Luminous efficacy
  • Pulsewidth modulation (PWM)

ASJC Scopus subject areas

  • Electrical and Electronic Engineering

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