LED SPEC
LED lifetime
LED LIFETIME is the declared period of time for which a LED light source maintains its high
quality and efficiency. Unlike traditional light sources, LEDs do not burn out suddenly – their
luminous flux gradually decreases over time. LED lifespan is most often defined as the number
of operating hours after which the luminous flux drops to a specific level, such as L70 – meaning
the fixture still emits at least 70% of its initial light output. In practice, L80 standard is applied
the most often.
LxxByy – What does it mean?
Lxx – Luminous Flux Maintenance
xx indicates the percentage of the initial luminous flux that remains after a specified operating time.
Example:
L70 → the diode emits at least 70% of the initial luminous flux
L80 → the diode emits at least 80% of the initial luminous flux
Byy – Parameter Spread (Non-Uniformity)
yy indicates the maximum percentage of diodes that may not meet the Lxx criterion. Example:
B10 → a maximum of 10% of the LEDs may have a flux lower than the specified level (e.g., L70)
B50 → up to 50% of the LEDs may fall below this value
Examples in practice
L70B10 60,000 hours
After 60,000 hours:
At least 90% of the LEDs operate at a brightness ≥ 70% of their initial value
L80B50 50,000 hours
After 50,000 hours:
Half of the LEDs retain at least 80% of their initial flux
LUMINOUS FLUX
TIME
70%
100%
Draw L70B10: after the specified operating time, 90% of
LED diodes emit at least 70% of the initial luminous flux.
L70B10
At least 90% of the LEDs maintain 70% of the initial luminous flux
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