Please use this identifier to cite or link to this item: http://hdl.handle.net/10397/13568
Title: On driving techniques for LEDs : toward a generalized methodology
Authors: Loo, KH 
Lun, WK
Tan, SC
Lai, YM 
Tse, CK 
Issue Date: 2009
Source: IEEE transactions on power electronics, 2009, v. 24, no. 12, 5233853, p. 2967-2976
Abstract: 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.
Keywords: Bi-level driving
Dc
Diode I-V characteristic
High-brightness LED
Lighting system
Luminous efficacy
Pulsewidth modulation (PWM)
Publisher: Institute of Electrical and Electronics Engineers
Journal: IEEE transactions on power electronics 
ISSN: 0885-8993
EISSN: 1941-0107
DOI: 10.1109/TPEL.2009.2021183
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