COB efficiency Spreadsheets

Greengenes707

Greengenes707

Well-Known Member
It took me and supra about 3 different occasions to actually figure out the discrepancy between the data sheet and and the PCT with the CX lines.
Here you go below VVVVV
SupraSPL said:
That may be the answer (a 30C discrepancy at test current), the fact that the PCT is ignoring the difference between Tsp/Tc and Tj, if the PCT is showing us lumens based on Tsp/Tc, when we select 85C that is actually a Tj of ~115. So if we correct it by selecting 55C (actual Tj of 85C) the PCT returns a figure higher than the minimum lumens.

If so, another way to put it the PCT is based on Tc rather than Tj. You can see from the PDF that at 1.9A a Tc of 55C = Tj of 85C

View attachment 3463681
Click to expand...
As well as cree uses min figures in the PCT.

Here was where we kind of pinpointed it...
https://www.rollitup.org/t/ppfd-what-sort-of-performance-for-this-setup-and-space.877135/page-2#post-11768359
 
JorgeGonzales

JorgeGonzales

Well-Known Member
Greengenes707 said:
It took me and supra about 3 different occasions to actually figure out the discrepancy between the data sheet and and the PCT with the CX lines.
Here you go below VVVVV


As well as cree uses min figures in the PCT.

Here was where we kind of pinpointed it...
https://www.rollitup.org/t/ppfd-what-sort-of-performance-for-this-setup-and-space.877135/page-2#post-11768359
Click to expand...
Which is a terrible thermal resistance if that is true, which I have assumed it is up until this point. Yet @guod says Cree has thermal resistance inline with Bridgelux, but I don't see how both things can be true at the same time.
 
V

voon

Well-Known Member
View attachment 3707503 View attachment 3707200
Greengenes707 said:
It took me and supra about 3 different occasions to actually figure out the discrepancy between the data sheet and and the PCT with the CX lines.
Here you go below VVVVV


As well as cree uses min figures in the PCT.

Here was where we kind of pinpointed it...
https://www.rollitup.org/t/ppfd-what-sort-of-performance-for-this-setup-and-space.877135/page-2#post-11768359
Click to expand...
if I understand correctly .. according SupraSPL and datasheets to CXB3070 by matching the correct value should be used in the testing and the corresponding curve in the graph at 100% light output @ 1900 mA Tc55 ° C, although the specified test Tj 85 ° C?
Tj 85 °C = Tc 55 ° C
Tj = Tc -30 ° C
Tj25 ° C = Tc -5 °C :-D
however i used the configurator, have a value of about 3% deviation .. it is a deviation assigned by the manufacturer?
 

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JorgeGonzales

JorgeGonzales

Well-Known Member
voon said:
if I understand correctly .. according SupraSPL and datasheets to CXB3070 by matching the correct value should be used in the testing and the corresponding curve in the graph at 100% light output @ 1900 mA Tc55 ° C, although the specified test Tj 85 ° C?
Tj 85 °C = Tc 55 ° C
Tj = Tc -30 ° C
Tj25 ° C = Tc -5 °C :-D
however i used the configurator, have a value of about 3% deviation .. it is a deviation assigned by the manufacturer?
Click to expand...
That tool is useless if you trust SupraSPL, it's current droop is also inaccurate once you step outside of Tj 85 = Tc 55, just compare them at different currents and you'll see. Just ignore it or trust it completely, that's what I say.
 
Stephenj37826

Stephenj37826

Well-Known Member
Greengenes707 said:
It took me and supra about 3 different occasions to actually figure out the discrepancy between the data sheet and and the PCT with the CX lines.
Here you go below VVVVV



As well as cree uses min figures in the PCT.

Here was where we kind of pinpointed it...
https://www.rollitup.org/t/ppfd-what-sort-of-performance-for-this-setup-and-space.877135/page-2#post-11768359
Click to expand...
This is another point I was trying to make in the phosphor conversion thread. As Cree PCT/Data sheet gives us our bin such as cxb3590 3500k 80ra CD bin it bugs me that cxb3590 4000k/5000k 80 Ra also falls into CD bin as well. If I'm understanding what's happening with the phosphor conversion then I can comfortably say that there is no way that 3500k will have the same luminous flux on average vs the 4000k/5000k. Sphere testing is needed to clarify a few questions in my head. Not doubting Crees nor Supras numbers just want to know where in the bin these different CCTs land. Just a thought
 
V

voon

Well-Known Member
Stephenj37826 said:
This is another point I was trying to make in the phosphor conversion thread. As Cree PCT/Data sheet gives us our bin such as cxb3590 3500k 80ra CD bin it bugs me that cxb3590 4000k/5000k 80 Ra also falls into CD bin as well. If I'm understanding what's happening with the phosphor conversion then I can comfortably say that there is no way that 3500k will have the same luminous flux on average vs the 4000k/5000k. Sphere testing is needed to clarify a few questions in my head. Not doubting Crees nor Supras numbers just want to know where in the bin these different CCTs land. Just a thought
Click to expand...
I surrender .. I'm not able to compare and find the correct value Tj or Tc PCT cree .. It seems that this is the most CXB3070 similarity with the data in datasheets
datasheet Tj = 85 ° C = Tc = 55 ° C and in PCT = Tj = 61 ° C = Tc
datasheet Tj = 25 ° C = Tc = 25 ° C and in PCT = Tj = 12 ° C = Tc
... In PCT Tj = Tc?
Who is in it can make sense? .. It seems like just very inaccurate and incorrect
.. Unable to find a match nor SupraSPL
 

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flexy123

Well-Known Member
Does someone have the actual *spreadsheet* for the CXB3590,36V, 3500K, CD bin? (and not just the images)

Thanks! :)
 
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