Lifetime
of LEDs
LEDs do not burn out like conventional bulbs or tubes.
Instead,
the lifetime of LEDs is characterized by
aging of chip and phosphor.
Aging of
the chip results in gradual decrease of
brightness while aging of the phosphor will shift the light color
towards blue.
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For the
chip aging the main factor is the
temperature. SMD LEDs have a clear advantage because of their cooling
possibility.
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Phosphor
aging is a quality issue, good
phosphors can stand 100,000 hours and more with only little
degradation.
End of life
for LED lighting is therefore
defined as the time when the brightness decreases below 70% (L70) or
50% (L50)
of its initial value.
