# cree XLamp CXA3050 erray



## wellmonster (Sep 21, 2013)

Hi guys,

first post here, so I'd like to say hi and hello and I hope the community can help me. now ivevonly recently discovered these LED's and im shocked to see these are aproaching hid intensity :O up to 9000 lumens. so what im trying to do is make a erray of these leds toalling about 300 watts and try and get it running at almost ambient temperature. 

So I fugured to keep the temperature In check and intensity high I would need a decent heat sink. something like a cpu heatsink with a fan attached comes to mind. I could get many of these at a cheap price, holes would be tapped and the leds screwed down with some arctic silver 5 or something. 

So, having never used this type of led nor have I done anything using such a high wattage. I was hoping to get some guidance for this build. im not sure about what psu to use or led driver/resistors if necessary, here are the specs on the LED.

Size (mm x mm) 27.35 x 27.35
Maximum drive current (A) 2.5
Maximum power (W) 100
Light output (lm) 5000 – 10000
Typical forward voltage @ 1.4 A (V), 85°C 37
Viewing angle (degrees) 115
Binning 85°C, ANSI White, 2- and 4-Step EasyWhite®
RoHS and REACH-compliant Yes

I was looking to use the 2700 -3000k color spectrum.

thanks in advance,

wellmonster


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## foxtrot824 (Sep 21, 2013)

Welcome to the CPF!

The larger CXA arrays are fun. You should look into some serious cooling for these if you plan on making an array of these. Depending on the life you expect and the exact application you will need to work out a few details. Will you be running these from line power AC (120v-277) or from a battery? As for drivers I'd recommend looking into Meanwell drivers, something in the constant current offering. As for attaching them to the heat sink currently the only mechanical holder specific to the 3050 is one made by Ideal Industries. Not sure if they are sold in small quantities. You mentioned thermal paste, that will be extremely necessary to prevent the chip from going up in smoke. 

Good luck with your build and please post pictures of the build if you have a chance.


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## wellmonster (Sep 21, 2013)

foxtrot824 said:


> Welcome to the CPF!
> 
> The larger CXA arrays are fun. You should look into some serious cooling for these if you plan on making an array of these. Depending on the life you expect and the exact application you will need to work out a few details. Will you be running these from line power AC (120v-277) or from a battery? As for drivers I'd recommend looking into Meanwell drivers, something in the constant current offering. As for attaching them to the heat sink currently the only mechanical holder specific to the 3050 is one made by Ideal Industries. Not sure if they are sold in small quantities. You mentioned thermal paste, that will be extremely necessary to prevent the chip from going up in smoke.
> 
> Good luck with your build and please post pictures of the build if you have a chance.



thanks ror your reply, the plan would to yes use ac power and I uad a look at the meanwell drivers and the CEN-100-42 looks to be the go. now I've never had the opportunity to use these drivers before. are they simple enough to use? the heat sink will take some looking but esthetics arnt important here. im sure I can find a large one and find a nice fan for it. 

I will definitely take pictures when the day comes, any suggestions to help optimize this would be great. ambient temperature shouldn't exceed 20 degrees Celsius.


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## foxtrot824 (Sep 21, 2013)

Let's start with heat sinks. There is a company called Nuventix based out of TX. They sell active cooling solutions LED lighting, Future Electronics sells their products. The only "issue" with the Synjet is that it wants to see constant voltage of 5v or 12v so you'll need an additional driver or regulator. The next step will be the mechanical attachment to the heat sink, if you are just making one or two of these I'd recommend "making you own holder" using a TE Connectivity holder. The Meanwell driver looks just fine, the current is adjustable via a small pot (just use a small screw driver to turn it). If you were doing a DC driver (off a 12v or 24v power supply, really anything up to about 33v) you would be looking for a boost driver. 80w-100w is a lot for an off the shelf driver so that might be a little tricky. As for pictures you can look for a image hosting sight that will automatically resize the images and give you a link to just paste in the post.


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## DIWdiver (Sep 21, 2013)

That Meanwell supply looks pretty close to ideal. It should be VERY easy to use. Put a power plug on one end, an LED on the other, and plug it in. It may not have enough voltage to drive the LED to full brightness until it warms up (the LED, not the supply). And it can't push the absolute max current through the LED, but that just keeps you from blowing it up too quick. 

You might want to turn the voltage adjustment all the way up and the current adjust all the way down before starting, and monitor the LED temperature carefully to make sure it's not overheating. Then turn up the current adjust as you see fit. 

I don't know much about CPU heatsinks, but I know that this one http://www.mouser.com/ProductDetail/Wakefield/557-140AB/?qs=sGAEpiMZZMttgyDkZ5Wiuita4PD18Ap7PEDmVbrAyv4%3d with a tornado blowing across it (high velocity fan carefully ducted so ALL the air goes through the heatsink) is good to about 60W. It's almost twice the size of a Pentium heatsink. To handle 100W, a heatsink would need quite a bit more surface area, very good airflow, and probably should be made of copper, unless it's quite a bit bigger than this one. Some CPU fan/heatsink combos would meet those requirements, some would not. I have a combo off an old motherboard that was getting scrapped, it's a copper heatsink with lots of fins and an integrated fan. It looks like it might do 100W and keep the junction temp below 90C, which is the max allowable at 2.25A, which is the max you can get out of the Meanwell. I'd love to play with it, but there's just so much time in the day...


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## wellmonster (Sep 21, 2013)

ok, thanks for the pointers, im glad to hear the driver is ideal enough. I had a look for heat sinks and found this http://www.silentpcreview.com/article186-page1.html that is a big *** heat sink lol and designed for 120mm fan which run very quiet. what do you guys think? I would get 4 of these and bind them together with some aluminum strips and hope to got its good enough. I expect to test it for a long time. last thing I need is this burning my house down. 

can any of you suggest a good place to pick these LED's up from? im here in Australia so online store im guessing is my only option. 

thanks again guys.


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## wellmonster (Sep 22, 2013)

check this out. http://www.circuitsathome.com/diy-2/high-power-led-grow-light-a-build-log 
this gus has done virtually the same thing I want to do. but with smaller xlamp. this is promising news just looking at the specs on his heatsink and comparing them. he has the lamps at 48w with cpu heatsink rated for 70w load. hes getting temps just above ambient. I think ill go woth four leds in a square fassion and probly wont run them as hard as I can. im thinking this will be far more useful then going hid.


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## wellmonster (Sep 22, 2013)

just curious, is it viable to stick these LED's to the heatsink with some kind of thermal epoxy? to avoid drilling the heatsink?


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## IMSabbel (Sep 22, 2013)

wellmonster said:


> ok, thanks for the pointers, im glad to hear the driver is ideal enough. I had a look for heat sinks and found this http://www.silentpcreview.com/article186-page1.html that is a big *** heat sink lol and designed for 120mm fan which run very quiet. what do you guys think? I would get 4 of these and bind them together with some aluminum strips and hope to got its good enough. I expect to test it for a long time. last thing I need is this burning my house down.
> 
> can any of you suggest a good place to pick these LED's up from? im here in Australia so online store im guessing is my only option.
> 
> thanks again guys.


Thats an ACIENT heatsink. Like a decade old.

There are TONS of cheap CPU heatsink that can easily deal with anything that LED array can put out. Remember, those things are designed to deal with 100W AND keep the CPU below 80C or so (often FAAR below, to allow overclocking), while still being pretty silent.

http://geizhals.eu/cooler-master-hyper-212-evo-a684731.html?v=l
http://geizhals.eu/arctic-cooling-freezer-xtreme-rev-2-ucaco-p0900-csb01-a411061.html?v=l
http://geizhals.eu/ekl-alpenfoehn-gross-clockner-rev-c-84000000018-a972105.html?v=l
These should all be plenty fine alone by themselves, and are all very affordable.

Are the leds available at cutters? that would be the first to come to my mind for getting them in australia...


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## DIWdiver (Sep 22, 2013)

Wow, that's a big heatink! If money is no object, it should do quite well. 

It should be possible to use epoxy. 
I wouldn't trust the temperature measurements in that build log. I don't believe that with ~40W going into the heatsink, that it didn't even get warm, even 1 degree above ambient. That's simply ridiculous. He probably used an infrared thermometer, which can't read on bare aluminum. If you want a good reading, you have to put something on it with decent emissivity, like a piece of black electrical tape. Even a simple sanity check, like putting you finger on the heatsink, would have told him his measurement was wrong.


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## wellmonster (Sep 22, 2013)

> There are TONS of cheap CPU heatsink that can easily deal with anything that LED array can put out. Remember, those things are designed to deal with 100W AND keep the CPU below 80C or so (often FAAR below, to allow overclocking), while still being pretty silent.
> 
> http://geizhals.eu/cooler-master-hyp...84731.html?v=l
> http://geizhals.eu/arctic-cooling-fr...11061.html?v=l
> ...




haha yea it is ancient i guess, looks liek most of the recent ones would work no prob most of the new cpu's are 125w and i mean my pc at 100% load hits 50 maby with prime95. and thanks! they are at cuters  $50 each tho. Still a store bought 400w led grow light is like $1k and they usually use 3-5 watt red blue and white led's and pathetic heatsinks. 



> It should be possible to use epoxy.
> I wouldn't trust the temperature measurements in that build log. I don't believe that with ~40W going into the heatsink, that it didn't even get warm, even 1 degree above ambient. That's simply ridiculous. He probably used an infrared thermometer, which can't read on bare aluminum. If you want a good reading, you have to put something on it with decent emissivity, like a piece of black electrical tape. Even a simple sanity check, like putting you finger on the heatsink, would have told him his measurement was wrong.



As much as i hope your wrong about the temps i suspect your right. I thought it sounded a bit fishy. when i'm testing i'll try the black tape. So is this what i need for the LED's ? http://www.cutter.com.au/proddetail.php?prod=cut827 

cheers.


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## wellmonster (Sep 22, 2013)

These heat-sinks are rated for 115 W and are $19 and also not that bulky, which will be handy in small spaces. what do you think? $80 on heat-sinks is much more desirable then $200.


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## eatkabab (Oct 14, 2013)

[FONT=Arial, Helvetica, sans-serif]I've been looking at these new LED 'pads' and was hoping you guys could help me with a few questions.

I'm coming from the world of XPG, XPE, XPC... and specifically looking at the CXA1304 with the 6mm die. It appears they say on the datasheet 9v and 37v with adjusted current such that both are around ~3.65w, but there aren't different versions right? As in, the same one can do 9v through 37v and pulls the according current it needs, correct?

From what I know with the XPG and such, their voltage/current curves are tied. If you feed 3v into an XPG, it draws 400ma or whatever. If you feed it 3.3v, it draws ~800ma. If you limit it's current to 400ma, it only draws 3v even if it's got plenty of voltage headroom. Do these work the same way? The numbers don't seem to support this theory however. It seems very counter intuitive that the CXA will drop it's current draw as you move from 9v-37v.

This leads me to believe that either there are two different versions, or this LED pad is extremely unregulated and just sucks up power unless it's carefully regulated. If there are in fact two voltage versions, the 9v version has a range from 8.5-11v as indicated by the datasheet, but the purple line on the chart which I believe represents the high CRI warm white version cuts out at 9.75v. What exactly does that mean? Don't push it past that because the thermal junction can't support it?


CXA1304 datasheet:
[/FONT]https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=2&ved=0CDgQFjAB&url=http%3A%2F%2Fwww.cree.com%2F~%2Fmedia%2FFiles%2FCree%2FLED%2520Components%2520and%2520Modules%2FXLamp%2FData%2520and%2520Binning%2F20130621CLDDS73CXA1304Rev0.pdf&ei=dY5cUob0DpCLkAeq7IGwBw&usg=AFQjCNGr537CPg2k39WmyLme1f0QkxRiAA&sig2=3xIskCM0AYjLiuU_b0z_-g&bvm=bv.53899372,d.eW0


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## langham (Oct 14, 2013)

Not sure why no one has said this yet, but in order to design your heatsink you should calculate the amount of waist heat generated by led inefficiency. You do this by multiplying the total power of the led by its efficiency. This will tell you how many watts are light and how many are being discipated in the form of heat. Some of that heat does get projected forward, but most of it is directly thought the back of the led. I read mention of the fact that single leds are mounted to stars and the thermal conductivity of the tin/lead in the solder, well most of the time that is not the major concern. Most of the time you are talking about a layer of tin/lead that is microscopic, the bigger issue is when the material that you are mounting the led to has a thermal barrier. For example if you buy a cheap chinese MCPCB you will notice that there is no electrical conductivity between the top of the thermal pad and the bottom of the star. That is because it is a lot easier to just have one piece of continuous insulation to seperate the positive and negitive leads from the electrically conductive heat sink.

You will see major efficiency gains if you use direct copper mounting. That is the only way to do what you want to do, the trick is not to keep the temperature of the heatsink down. It is actually the opposite you want the heatsink to be as hot as possible to allow for excellent heat trasfer. The temperature you are worried about is Tj which is at the led. The best way to get rid of heat from the led is with copper. Copper holds twice the energy per unit mass as alluminum does, and will allow it to store more energy prior to dissipation. You should use a liquid cooling system for your application with direct copper mounted leds, and active cooling. I am in the buisness of getting a lot of performance from my leds and I drive an XM-L2 at 6A with no problems, using this method. I use artic silver 5 to mount my copper heatsinks to the pills of the flashlights that I build and I see excellent performance.

Take a look at this http://www.candlepowerforums.com/vb...adlight-formerly-quot-flying-searchlight-quot it is a cool project that had some of the same issues. There is an equation for calculating active cooling surface area per watt of heat input, you should be able to find it with a simple search. To be honest the first thing that comes to mind for me is the DX SKU: 168525 or SKU: 213009. I don't know if that is what you are looking for, but they are cheap, and you could put a bigger fan on there if you would like. Something else you could do is just mount the leds to a pure copper bar, like a grounding bar or a peice of bus work and then attach the heat-sink to that, and then it wouldn't matter what type of heatsink you used as long as it could handle the total energy. Good luck I will look in to see your progress, and :welcome:


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## Steve K (Oct 15, 2013)

The idea that a hot heatsink will help keep the LED cool is rather misguided. It does increase the heat transfer to the air, but it also means that the LED is hot (since it will always be hotter than the heatsink). Of course, that doesn't mean that a cool heatsink is always better, since it could just mean that there is too much thermal resistance between the the LED and the heatsink. Basically, the lesson is that the heatsink temperature isn't what you need to be worrying about.... it's the LED junction temperature that matters.

As a primer, I'd recommend becoming familiar with Cree's application note on thermal magagement.. 
http://www.cree.com/~/media/Files/C... Application Notes/XLampThermalManagement.pdf
In particular, the concept of thermal resistance is important, as is the ability to run the calculations yourself.


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## langham (Oct 20, 2013)

So what you are saying is that my statement is incorrect, but you need to be worried about Tj, kind of like I said? Like I said the temperature of the heat-sink should be as high as possible to allow for better heat transfer. The way you keep Tj down is buy using good materials with minimum thermal resistance. The thermal efficiency of any heat engine is directly proportional to the difference in temperature between the heat source and the heat sink. Although it is hard to conceptualize what the actual heat-sink is. In this case the heat sink for the led is the star that it is mounted to, or the copper/aluminum. That will set up the first part of your design and then you will have a second heat-sink for the star (the cpu cooler) or the air. You can raise the amount of heat that is removed using this equation Q=mc(Ts-Tsink) where Q is the thermal heat transfer, m is the mass flow rate, c is the constant for your system, and then the difference in temperature from your heat source and heat sink. Now you know that the c can only be changed in the initial design stage and after that you have to change either the mass flow rate of the air/liquid or you can change the difference in temperature. The way most CPUs are set up is to maintain the temperature below a certain value, that way the computer can be as quiet as possible and you can keep it as clean as possible (an excessive buildup of dirt makes you c value go down over time). The fan changing speeds raises your mass flow rate and the Q value, but the c value remains constant and effectively the difference in temperature will remain the same as well due to the higher heat load. In your case though you will have a constant heat load, and will most likely have a constant speed on your fan so the only variable will be ambient temperature once you know the constant for you application. You could calculate this value or you could just solve for it after you know the rest of the variables. You can look up this formula it is commonly known as mc delta t and this specific one should have a small dot over both the Q and the m.


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## Steve K (Oct 20, 2013)

I think you assuming that "better heat transfer" from the heatsink automatically means the led junction temperature will be low. This isn't true.

For example, how about a case where the ambient air is 25C and you want to keep the junction temperature no higher than 50C. If the heatsink is relatively small, you might get the heatsink temperature up to 200C, but I can fairly well assure you that the led junction temperature will not be 50C! The led junction temperature is by definition hotter than the heatsink, so if you want the junction to be no hotter than 50C, the heatsink temperature will have to be less than 50C. This will require a much larger heatsink than the case where the heatsink is 200C. The larger heatsink will have a lower thermal resistance, which also provides better heat transfer, but with the added benefit that you won't be able to boil water with the led.


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