# Is the Cree MC-E K-bin or Seoul P7 C-bin more efficient?



## AvPD (Sep 30, 2008)

I'm having trouble getting exact and equivalent specs and was wondering if someone could answer this authoritatively.


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## TexLite (Oct 2, 2008)

According to the datasheets;

The MC-E K bin is a _minimum_ 370lm @ 4.48W or 82.59 lm/W
(350ma and 3.2V typical,going by the datasheet)

The P7 C bin is _typical_ 400lm @ 4.62W or 86.58 lm/W
(1400ma @ 3.3V,again,going by the datasheet.)

Quite honestly,I think its a wash.

Some things to bear in mind;

The datasheet for the P7 list typical Vf as 3.6 @ 2800ma.The C bins that are currently available are a maximum of 3.5 Vf at 2800ma.So it seems the available product will actually be more efficient than the datasheet would indicate.

The same seems to hold true for the MC-E as well,the samples that have been tested so far have been below the datasheet spec of 3.4V @ 700ma.McGizmo tested one at 3.3Vf @ 700ma,again,better than the datasheet would suggest.

This,coupled with the fact they use the same die,leads me to speculate they will be equal as far as efficiency.

As a side note,the D bin P7's are widely available now,and the M bin MC-E has also shipped from Cree.

-Michael


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## AvPD (Oct 2, 2008)

I just downloaded the latest P7 spec sheet for pure white that doesn't even mentioning binning (just says 700lm typical, 900lm max). 700 lumens from 3.6V x 2.8A = 10.08 watts is only 69.4 lumens per watt, so that would mean that the efficiency drops off quite a bit above 1400mA.

If they're basically the same efficiency than Cree's only advantage would the smaller size and individually addressable dies.


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## orbital (Oct 2, 2008)

TexLite said:


> According to the datasheets;
> 
> The MC-E K bin is a _minimum_ 370lm @ 4.48W or 82.59 lm/W
> (350ma and 3.2V typical,going by the datasheet)
> ...



Good post Michael!...


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## Oznog (Oct 2, 2008)

The effect of the thermal solution is more significant than that spec sheet difference. P7 is kinda hurting because of the greater power density in that device. If you have a 6C/W MCPCB then it's running cooler thus more efficient with 5W than 10W (or whatever). 30C right there.

The MC-E also has an electrically neutral thermal path- which will have very favorable effects on the thermal resistance IF you don't use MCPCB. The mounted solution they sell is still an MCPCB from what I saw so it's not taking advantage of that feature.


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## TexLite (Oct 3, 2008)

AvPD said:


> I just downloaded the latest P7 spec sheet for pure white that doesn't even mentioning binning (just says 700lm typical, 900lm max). 700 lumens from 3.6V x 2.8A = 10.08 watts is only 69.4 lumens per watt, so that would mean that the efficiency drops off quite a bit above 1400mA.


 
Download the P7 _binning and labeling _pdf,the standard spec sheet dosen't have the binning info.

A P7 CSWOI for instance,would have a max Vf of 3.5.At 2800ma(9.8W),while producing between 700lm-800lm.The _lowest_ possible efficieny with that emitter would be 71.4 lm/W,using 3.5Vf and 700lm.

If you used middle of the road figures of 750lm,and 3.375Vf(I bin is 3.25Vf-3.5Vf),works out to 79.36 lm/W.Still pretty impressive.



AvPD said:


> If they're basically the same efficiency than Cree's only advantage would the smaller size and individually addressable dies.


 
Along with the electrically neutral thermal pad that Oznog has mentioned,thats the way I see it.



orbital said:


> Good post Michael!...


 
Thanks orbital,kindly appreciated.

-Michael


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## AvPD (Oct 3, 2008)

TexLite said:


> Download the P7 _binning and labeling _pdf,the standard spec sheet dosen't have the binning info.


I'm not _that_ lazy (had a copy on my HD, and have re-downloaded it from http://acriche.com/en/product/prd/zpowerLEDp7.asp) and I have not been able to find any of the figures you have quoted from it. Only that general spec sheet had a voltage and amperage figure.

By the way I appreciate your input, I feared the thread would fade away unanswered.


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## jirik_cz (Oct 3, 2008)

TexLite said:


> A P7 CSWOI for instance,would have a max Vf of 3.5.At 2800ma(9.8W),while producing between 700lm-800lm.The _lowest_ possible efficieny with that emitter would be 71.4 lm/W,using 3.5Vf and 700lm.



I think that Vf binning is for 1400mA current (350mA per die) not for 2800mA.


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## TexLite (Oct 4, 2008)

AvPD said:


> I'm not _that_ lazy


 
In no way did I intend to imply that,I wanted to clarify which datasheet the information I had posted came from.

The screenshot below is from page 5 of the Binning and Labeling datasheet.








AvPD said:


> By the way I appreciate your input, I feared the thread would fade away unanswered.


 
Your welcome,it was a good question and deserved an answer.I think some people are hesitant to answer around here because of combative posters.



jirik_cz said:


> I think that Vf binning is for 1400mA current (350mA per die) not for 2800mA.


 
Heres the info below,from page 4 of the standard W724C0 datasheet,notice the forward current at the top,2800mA.The 700lm-900lm and 3.6Vf-4.2Vf correspond to that current.Listed below those figures are the flux output and Vf at 1400mA.In short,binning(Vf and flux) are done at 2800mA.






-Michael


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## AvPD (Oct 4, 2008)

I hope I didn't come across as combative (just want to know for sure which is more efficient), regarding the figures it looks like the hours I keep might be catching up to me.
Looks like the only piece of information missing is the MC-E's lumens at 700mA per die/2.8A total

I am impressed with the humble C-bin P7's performance at lower wattages, I assumed they were battery hogs...


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## TexLite (Oct 4, 2008)

AvPD said:


> I hope I didn't come across as combative


 
No you didn't.I was referring to the length of time the thread had set with no answers.What I meant was I think people are hesitant to answer because of other posters being argumentative,not that your question was combative.



AvPD said:


> Looks like the only piece of information missing is the MC-E's lumens at 700mA per die/2.8A total


 
The cutsheet shows 790lm @ 700mA.The figures below would be between the specs listed in the datasheet,which has the latest updates.See the second capture for an explanation.





According to the below info from the datasheet,the flux output at 700mA would be around 1.75 times the output at 350mA.Using the M bin output of 430lm-490lm at 350mA,would put it at 750lm-850lm at 700mA,again right about the D bin P7 output of 800lm-900lm at the same power level.





-Michael


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