High hot/cold factor boosts HB-LED efficacy
Philips’ new Luxeon Rebel HB LEDs (high-brightness light-emitting diodes) have a 0.93 hot/cold factor—the ratio of junction temperatures at 100 and 25°C.
By Margery Conner, Technical Editor -- EDN, October 8, 2009
’ new Luxeon Rebel HB LEDs (high-brightness light-emitting diodes) have a 0.93 hot/cold factor—the ratio of junction temperatures at 100 and 25°C. The new devices thus beat typical specs for production LEDs, whose hot/cold factors range from 0.8 to 0.85. These factors are important in applications such as light-fixture luminaires, which spend most of their time operating at temperatures of 80 to 110°C—much higher than the 25°C junction temperature that most HB-LED spec sheets give as the light output. As its junction temperature increases, an LED’s light output and efficacy decrease.
This article originally appeared as an entry in the PowerSource blog.
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What it presumably means is that the luminous flux output of the LED die decreases by 7 percent when the device is operated at 100 degrees C junction temperature compared to test measurements performed at 25 degrees C.
Indignant comments about sloppy journalism suppressed.
ian Ashdown - 2009-19-10 13:20:00 PDT -
That's ridiculous! The ratio of their junction temperatures at 100 C and 25 C
is the ratio of these temperatures in
Kelvins, or 373/298 = 1.251. They must
mean something else.
Michael Riordan - 2009-8-10 15:25:00 PDT
