# Cree announces 276 lumens per watt!!! (okay just in a lab setting)



## foxtrot824 (Feb 13, 2013)

I just saw this press release

http://www.cree.com/news-and-events/cree-news/press-releases/2013/february/276-lpw

Looks like they achieved that at 4401K at a drive current of 350mA. I'm sure it will be a while until we see it in a package but still encouraging.


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## Stephen7372 (Feb 13, 2013)

foxtrot824 said:


> I just saw this press release
> 
> http://www.cree.com/news-and-events/cree-news/press-releases/2013/february/276-lpw
> 
> Looks like they achieved that at 4401K at a drive current of 350mA. I'm sure it will be a while until we see it in a package but still encouraging.



Hooooooooorayyyyyyyyyyyy !!!


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## LEDAdd1ct (Feb 13, 2013)

1 watt / .350 amps = 2.857 forward voltage

Is that right?

2.857 volts at 350mA = 276 lumens and at _4401K_?!

Nuts!


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## awenta (Feb 13, 2013)

A while may be an understatement but awesome nonetheless!


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## 2xTrinity (Feb 13, 2013)

foxtrot824 said:


> I just saw this press release
> 
> http://www.cree.com/news-and-events/cree-news/press-releases/2013/february/276-lpw
> 
> Looks like they achieved that at 4401K at a drive current of 350mA. I'm sure it will be a while until we see it in a package but still encouraging.



Makes sense that we'd see higher efficacy (lm/watt) at a lower color temperature. 4400k white has a lot more power density in the green where the eyes are much more sensitive.


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## Led_Blind (Feb 14, 2013)

Great, now when will they be released?


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## jtr1962 (Feb 14, 2013)

I'd love to know the WPE of the blue emitter here. Based on the numbers it looks like it might be pretty close to 100%.


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## LEDAdd1ct (Feb 14, 2013)

Wall Plug Efficiency:

"Wall-plug efficiency, a term in the optics field, typically refers to the effectiveness of converting electrical to optical power."

Source


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## BigRiz (Feb 14, 2013)

.. time for the usual R&D efficacy achievement chart


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## uk_caver (Feb 14, 2013)

That chart would be even better with curves for announced production efficacy (and available-to-buy device efficacy, though that might rely on various people's memories/records of when they first managed to get hold of a particular output bin).


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## BigRiz (Feb 14, 2013)

Well I agree with you but I don't have that information at hand, although I'll try to collect it one day..

btw judging by the trends, production is around 3-4 years behind R&D, and R&D efficacy has doubled in the last ~5 years. For how long this can go on is anyone's guess. I believe the theoretical maximum efficacy for white LED's is 260 - 300 lumens per watt.. so we might be hitting a wall very soon


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## awenta (Feb 14, 2013)

That may turn in to a crazy busy chart. 

R&D may hit a wall soon but we won't get that product for a long time. We just have to pretend we don't know and enjoy the emitters they release in the meantime.


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## WeLight (Feb 14, 2013)

CREE typically commercialise R&D into product in around 18 months


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## uk_caver (Feb 14, 2013)

Has that time lag been getting longer recently?
XPG-2s seemed to be available around the middle of last year, and they seem to be roughly 160lm/W, not far off 4 years behind the 'lab setting' curve.


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## awenta (Feb 14, 2013)

It's like that with everything. Have to milk everything you can.


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## Hooked on Fenix (Feb 15, 2013)

I wonder, with a cheaper and easier to produce l.e.d. and platform than in the past (SiC vs. chip based), won't we be seeing these l.e.d.s sooner than 18 months?


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## BigRiz (Feb 15, 2013)

I wouldn't hold my breath in expecting this within 18 months. As far as I can remember, production was always around 4 years behind R&D, and it will probably continue to be so. That's still good news however. With the current trend, we should be expecting to have LED's that exceed 200 lumens per watt within a year.


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## awenta (Feb 15, 2013)

Just imagine you didnt read this and be amazed as new emitters are released!


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## IMSabbel (Feb 15, 2013)

Hooked on Fenix said:


> I wonder, with a cheaper and easier to produce l.e.d. and platform than in the past (SiC vs. chip based), won't we be seeing these l.e.d.s sooner than 18 months?



Don't forget that this is two effects at play here.

In addition to the technology delay, this is also a single LED, the best hand picked from certainly quite a few wavers. If you want to compare it with production LEDs, you would need to buy a couple of thousand of the highest bin LEDs available and only take the best one.


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## uk_caver (Feb 15, 2013)

IMSabbel said:


> If you want to compare it with production LEDs, you would need to buy a couple of thousand of the highest bin LEDs available and only take the best one.


As long as the criteria used to work out 'average best retail available' or something like that are consistent over time, they'd be a reasonable basis for comparison even if they don't find the absolute best retail record breaker.

I'm not interested in the absolute best LED Cree released for sale, since I'm unlikely to buy it even in the absence of premium customers with first dibs on the very best products.

What I am _personally_ interested in is roughly the best LED I might expect to end up with if I go to Cutter or similar and buy a few dozen of the highest output bin LEDs available in a non-unpleasant colour, assuming I don't need them instantly and can afford to wait a week or two if what I _ideally_ want isn't in stock.
Other people may well have different criteria.


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## jtr1962 (Feb 15, 2013)

BigRiz said:


> I wouldn't hold my breath in expecting this within 18 months. As far as I can remember, production was always around 4 years behind R&D, and it will probably continue to be so. That's still good news however. With the current trend, we should be expecting to have LED's that exceed 200 lumens per watt within a year.


The best bin MK-Rs, which are being released around April of this year, will have ~200 lm/W efficiency at a 1 watt drive level. We'll probably have LEDs >250 lm/W at higher drive levels in 3 or 4 years if the delay between lab result and production holds at its current level.


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## uk_caver (Feb 15, 2013)

Do announced lab test figures (as in the Cree press release) all relate to some 'standard' die size, or could a manufacturer effectively boost the claimed output somewhat by making a physically larger test device?


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## jtr1962 (Feb 15, 2013)

uk_caver said:


> Do announced lab test figures (as in the Cree press release) all relate to some 'standard' die size, or could a manufacturer effectively boost the claimed output somewhat by making a physically larger test device?


Cree's lab test results all seem to be at the 1 watt drive level. I can't answer the question about die size, but I do know that as LEDs become more efficient the gains are smaller from increasing die size (or running at a lower power level). Back in the days of the Luxeon, you might see a 60% or 70% efficiency increase running at 20 mA compared to 350 mA. Now you're lucky to gain an extra 20%.


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## Dave44 (Jul 27, 2013)

Be aware that "record" lm/W numbers are usually obtained by pulsing the LED for very short times. This is so they can separate intrinsic efficiencies from effects associated with self heating - the so called Droop...

One reason for doing this is to avoid having to exquisitely heat sink each test LED for what is really a R/D LED...


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## bshanahan14rulz (Jul 29, 2013)

Dave44 said:


> Be aware that "record" lm/W numbers are usually obtained by pulsing the LED for very short times. This is so they can separate intrinsic efficiencies from effects associated with self heating - the so called Droop...
> 
> One reason for doing this is to avoid having to exquisitely heat sink each test LED for what is really a R/D LED...



I think it states that in the datasheets for their current LEDs, the published specs are under that condition as well, but always good to keep that in mind, since that is not how we use them.


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## jtr1962 (Jul 29, 2013)

Dave44 said:


> Be aware that "record" lm/W numbers are usually obtained by pulsing the LED for very short times. This is so they can separate intrinsic efficiencies from effects associated with self heating - the so called Droop...
> 
> One reason for doing this is to avoid having to exquisitely heat sink each test LED for what is really a R/D LED...


This LED was operating at ~1 watt power input. At the stated efficiency of 276 lm/W, at worst it was generating 0.2 watts of waste heat. This isn't enough to raise junction temperatures by more than a degree or two. The effect of this small of a temperature rise on efficiency would be close to nil.


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