LEDs life time?

[Aleksandar Stancic]

Hi everybody!

I'm using a LITE-ON LED diode LTL307EE.

Tha datasheet says:
Absolute maximum ratings at Ta=25C:
Continuous Forward Current = 30mA

Does that mean that the LED will not lose it's brightness
even after years and years of work (at 25C)?

Thank you!

 

[Spehro Pefhany]

Hi everybody!

I'm using a LITE-ON LED diode LTL307EE.

Tha datasheet says:
Absolute maximum ratings at Ta=25C:
Continuous Forward Current = 30mA

Does that mean that the LED will not lose it's brightness
even after years and years of work (at 25C)?

No, it means that they don't guarantee it will last a second at 31mA
and 25°C ambient. It says nothing about the life at the abs. max.
current, but one may guess it will be a fair bit less than it would be
at, say, 10mA and 20°C.

Best regards,
Spehro Pefhany

 

[Don Klipstein]

Hi everybody!

I'm using a LITE-ON LED diode LTL307EE.

Tha datasheet says:
Absolute maximum ratings at Ta=25C:
Continuous Forward Current = 30mA

Does that mean that the LED will not lose it's brightness
even after years and years of work (at 25C)?

Look up thermal resistance data for your LED or a similar one.

Many LEDs have thermal resistance of approx. 250 degrees C per watt, in
terms of temperature rise of the junction above the temperature 5 mm
outside the case on the lead that the chip is mounted on.

For really good life expectancy (at least half the original light output
after 100,000 operating hours) I advise having the junction not exceed 85
degrees C (some may tolerate a little more like 100 degrees C), maybe also
do not exceed 20 mA or not by much.
Keep in mind that violet and UV LEDs have shorter life expectancy, and
ones with phosphors (white, pink, purple, and Nichia's yellow) also have
shorter life expectancy at "full power".

- Don Klipstein ([email protected])

 

[Jim Adney]

Hi everybody!

I'm using a LITE-ON LED diode LTL307EE.

Tha datasheet says:
Absolute maximum ratings at Ta=25C:
Continuous Forward Current = 30mA

Does that mean that the LED will not lose it's brightness
even after years and years of work (at 25C)?

No, that just means that you should be able to put this much current
thru it without its dying rather quickly.

In general, LEDs which are run continuously at their max current
rating lose about half of their light output in one year of operation.
I assume that the rate of loss is much less if they are worked well
below their max.

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