# Cree Achieves Highest Efficacy from a High-Power LED



## Juctuc (Sep 13, 2007)

There is it http://www.cree.com/press/press_detail.asp?i=1189687350946

Is it just luck, here is another from this day also: http://www.led-professional.com/content/view/756/29/


So...is it K2 next??


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## LightForce (Sep 13, 2007)

Soooo basing on earlier Cree news it would be a 136 [email protected] and 1000 [email protected]  :duck:


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## jtr1962 (Sep 13, 2007)

135.7 lumens at 129 lm/W equals 1.052 watts. At 350 mA that means Vf is only 3.006V. This is much lower than previous XR-Es (3.25V is typical). Apparently a good portion of the efficiency increase then is just getting Vf down. According to Cree's binning system these would be R4. Considering that release of the R2s is probably imminent, I'd guess we'll be seeing these for sale in 6 months or so. I continue to be amazed at the rapid progress Cree is making. A year ago 75 lm/W was state of the art. Today we're pushing 100 lm/W. By this time next year we'll probably be at 130-140 lm/W.


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## LightForce (Sep 14, 2007)

Not only the Vf will be lowering, but we will see the improvement in the maximum current capability. The P4 Cree must to dissipate 3 watts of heat at 1000 mA and 3.55V. This is the slight barrier to pushing it further, considering its best lifespan.

R4 bin with lower Vf and much higher efficiency will dissipate 3 watts at 1200 mA, having only 3.3 Vf.

But the most incredible will be the brightness gain.
P4 at 1000 mA had 186 lm
R4 at 1200 mA will have impressive 335 lm
Near two times brighter!

Still dissipating 3W of heat...

R4 at 1000 mA will dissipate not 3W, but 2.4W of heat.
And it will have round 300 lm
Lossing 80% energy that P4 lossed...

R4 at 520 mA will have the same light output as P4 at 1000mA
This is the half power!
This is double runtime...

Future really looks bright 
Future looks cool
Future looks long-running 

Damian


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## HumanLumen (Sep 14, 2007)

Looks like the die is question is more revolution than evolution - see 

http://www.ledsmagazine.com/news/4/9/9

Quote "...John Edmond, who confirmed that the results are based on a next generation chip in which almost all aspects if technology – from epitaxial layer design to optical extraction to phosphor conversion – are not currently in production. A mix of evolutionary improvements and brand new, innovative approaches have been used. Individually, each of these improved technologies will begin to appear in production devices in the next 1-2 years.


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## frenzee (Sep 15, 2007)

These are exciting times indeed for us LED afficianados and modders.


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## 3rd_shift (Sep 16, 2007)

frenzee said:


> These are exciting times indeed for us LED afficianados and modders.


Yup.


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## TorchBoy (Sep 20, 2007)

Juctuc said:


> Is it just luck, here is another from this day also: http://www.led-professional.com/content/view/756/29/
> 
> So...is it K2 next??



From that article:


> With its upgraded packaging, Acriche is the only semiconductor lighting source capable of withstanding 4-watt level of high power.


What do they mean by that? My K2 does 5.8W.


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## J.D. (Sep 20, 2007)

Another interesting thing about this article:
" The warm-white (2,950 K) LED produced 104.2 lumens of light output and achieved 99 lumens per watt efficacy "

If the warm-white XR-E´s will become more efficient, they would be very interesting for the usage in flashlights.

Remember the outdoor problems (spooki, flat looking) of cold white leds compared to ican....


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## Free (Sep 20, 2007)

How about this array. Wonder what they are using:

http://www.enfis.com/news/press_releases16.htm


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## 3rd_shift (Sep 20, 2007)

A focussable led flashlight mod at 1300+ lumens might get quite interesting with this animal.


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## Calina (Sep 20, 2007)

TorchBoy said:


> From that article:
> 
> What do they mean by that? My K2 does 5.8W.


 
The Acriche works directly with an AC source instead of DC like all the other LEDs.


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## TorchBoy (Sep 21, 2007)

Calina said:


> The Acriche works directly with an AC source instead of DC like all the other LEDs.


Yes, but that's not what they said. You're likely right on what they meant, tho.


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## Martini (Sep 22, 2007)

So, do you guys think this large die will actually go to market? If so, then it's back to the drawing board with reflectors. A larger die would be okay, so long as the radiation pattern is wider (lambertian would be nice). That way, with reflectors of similar depth, the new die wouldn't lose throw as compared to the XR-E.

And if the XR-E is going to be replaced in the near future, it may well be worth waiting a few months for the higher bins (R3, R4) since they could be the last LEDs made to fit our current XR-E reflectors. Change happens fast.


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## Oznog (Sep 22, 2007)

frenzee said:


> These are exciting times indeed for us LED afficianados and modders.



No, annoying as hell. You bust your *** to put together the coolest, most advanced flashlight evar and then you find out it's going to be obsolete a few months later.


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## HumanLumen (Sep 23, 2007)

I don't think the die will be that much larger; if we assume for a moment that the die was 1.2mm per side rather than the aprox 1mm, then the area would be 1.44 times greater, thus 136 lumens (at 350mA) divided by 1.44 would be 94.4 lumens/mm squared (at 350mA) - this is less than the current XR-E and thus may appear to be a step backwards in surface brightness. Based on this sort of reasoning, I think we assume that we are not talking about large differences in geometry. However, I would appreciate the larger die as it would be usefull for aspheric lenses which project an image of the die - I am currently using a short focal length lens (15mm) which gives a reasonable size hotspot, albeit at lower brightness than a longer focal length lens with a more compact image (but still achieving 17,100 lux at 1m at 917mA with a Q4 with a 30mm lens). A larger die would be most welcome!


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