LED life
LED life
(OP)
Can anybody suggest a good LED reference? I am specifically concerned about degradation of the LED over time. What would a curve of luminous vs time look like? I expect to run the LED's at about 12-15mA.
Thanks
scoreb
Thanks
scoreb
RE: LED life
I know that blue LEDs don't last anywhere near as long as red LEDs. High brightness LEDs run at about 1/3 maximum current, give the same brightness as a run-of-the-mill LED when operated at a nominal 15 ma, but will last at least twice as long. You have to play with the curves.
What brightness level at what lifetime are you looking for?
RE: LED life
Normally you would be sseing a LI ( Luminious intensity)
degradation of about 15 to 30 percent if you operate at Room
temp Burn in at maximum current rating of the product specs over a period of 1000 hours.
If the degradation is more than 30% eyeball judgement could
tell you cleary that the LED has degaraded and this is the
limit where most Manufacturers wouldnt want to go.
To improve the degradation (ie prevent LI loss ), I would recommend that the LED be operated at a low duty cycle 10%
to 20% with high current levels not exceeding the peak forward current of the product spec. Osram Semiconductors may include degradation curves in their product spec.
Joy to you.
RE: LED life
If this is a serious concern, press the manufacturer of your device for details and life test data for the part you are planning to use.
Even though red GaAs LEDs have (in general) become pretty stable over the years, some more exotic LEDs, especially the white types, can have pretty dramatic degradation curvers. Again, the only way to answer the question is to work with the manufacturer.