Luxeon Star...

[Elmie]

Just wondering, what is the life span of the luxeon star rated at?

Cause for the nichia led's they say that they last for 100,000 under normal use.

Just wondering how the two compare in that department.

 

[The_LED_Museum]

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by Elmie:
Just wondering, what is the life span of the luxeon star rated at?<HR></BLOCKQUOTE>

White, blue, blue-green, green LS:
At 8,000 hours, the output will degrade up to 20%.
At 80,000 hours, this loss (from new value) is at 30%.

For red & amber LS, it looks like a 20% loss at around 5,000 to 7,000 hours, and a 36% loss at around 85,000 to 90,000 hours.

A common figure given for 5mm LEDs like Nichia is a 50% degradation at 100,000 hours.

These figures assume the LS is driven at 350mA (white, green, blue-green, blue) or 385mA (amber, red).
Degradation will probably be much less pronounced at lower values - even taking 50mA off will probably cut the total intensity loss to 10%-15% or so over 70,000+ hours; though I have no direct evidence to support this theory.

 

[vcal]

Stingmon, that's still a heckava lot of 1000s of hours.

 

[PeLu]

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by Stingmon:
A common figure given for 5mm LEDs like Nichia is a 50% degradation at 100,000 hours.

These figures assume the LS is driven at 350mA (white, green, blue-green, blue) or 385mA (amber, red).
Degradation will probably be much less pronounced at lower values - even taking 50mA off will probably cut the total intensity loss to 10%-15% or so over 70,000+ hours;<HR></BLOCKQUOTE>

AFAIK both of them assume that you keep their heatsink at 25°C, which is only possible in a laboratory. And if you overdrive/underdrive them, every 10K hlafs/doubles the lifetime (or the time to a specific point) as a rule of thumb. As we know the thermal data, we could easily calculate (ok, estimate) it.

 

[PeLu]

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by Elmie:
Just wondering, what is the life span of the luxeon star rated at?
<HR></BLOCKQUOTE>

The usual 100,000 hours for Nichia gives only a very, very rough figure. Luxeon is much more honest tehre and explains their life expectancy.

Luxeon says that for a 70°C junction temperature (which is a very realistic number when beeing careful) light output should decrease for some -20% at 4,000 hours and -30% at 40,000 hours.

When driving this led with 350mA you have to keep the backplane at some 50°C to keep the junction at 70°C.

Luxeon LEDs do not contain any epoxy, so they are not affected by epoxy degradation (like others).
I know a person who managed to overdrive a white Nichia LED so it came down to 50% brightness or less in 100 hours. Have to look what the current was.

Also light output drops when the junction temperatur rises (and vice versa).