# what's the difference between XML vs XML2 ?



## picard

what's the difference between XML vs XML2 ?

Is there big difference? 

does XML2 have tighter spot ?


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## DellSuperman

XM-L2 is the 2nd generation XM-L. 
It has better efficiency so it should produce more lumens. 
The difference stated by the manufacturer is roughly 20% improvement. 

As for hotspot brightness, it should depend on the reflector or optic rather than the emitters you mentioned. 

- JonK


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## BeastFlashlight

When do u guys think XML3 will come out? XML4? How fast do u see these LEDs evolving, maybe 1 level of improvement per year? I'm shocked that NEW lights are still coming out with XML U2 that's 2 bins back from the current best.

I hope that the voltage requirements and drivers of XMLs stay compatible down thru the years because I'd really like to be able to simply swap out my LEDs on my custom lights as they improve. I have really nice custom hosts (all with XML2)


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## maoku

XML2 20% higher than XML on the brightness, and the encapsulaiton is different


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## BeastFlashlight

And hopefully XML3 will be 20% brighter than XML2, than XML4 will be 20% brighter than XML3...


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## TEEJ

BeastFlashlight said:


> When do u guys think XML3 will come out? XML4? How fast do u see these LEDs evolving, maybe 1 level of improvement per year? I'm shocked that NEW lights are still coming out with XML U2 that's 2 bins back from the current best.
> 
> I hope that the voltage requirements and drivers of XMLs stay compatible down thru the years because I'd really like to be able to simply swap out my LEDs on my custom lights as they improve. I have really nice custom hosts (all with XML2)



There's no set amount of improvement. Sometimes, they make the die smaller, and throw is improved, sometimes they squeak some more lumens out of them, etc.

The way I see it, just get the light that does what you need it to NOW. If its working for you, you're done. If you want a light that's smaller but the same performance, or, find it WASN'T working for you...then get a better light when available, and so forth.


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## ROB21

So, does it generate the same amount of heat at the same lumen value?


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## yifu

Ok here are the improvements...
-Die shrink of around 10%
-Die change to new SiC generation (new process beginning with the XB-D)
-Binning at 85 degrees celsius(used to be 25 degrees)
-Removal of current spreaders and reduction in bond wires by 1(so we can drive it to 6A without the wires melting:devil:
-Efficiency increase of around 10% (at 85C)
-Substantial cost reductions (half the lumen per dollar cost)
-Longer L70 lifetime
-And dome is easier to remove (personal experience)...

I think it's a good upgrade.


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## Verndog

ROB21 said:


> So, does it generate the same amount of heat at the same lumen value?



If it is more efficient, then no, it would generate LESS heat at the same lumen value.


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## BeastFlashlight

TEEJ said:


> The way I see it, just get the light that does what you need it to NOW. If its working for you, you're done.


I'm pretty satisfied with my mods, but the #1 reason i will continue to upgrade the LEDs if I can will be for the improved light to heat ratio, the ideal goal being the point where they can run continuously without over heating. Like the SolarStorm that we have how great would it be for that to handle the heat continuously?


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## PocketBeam

Let's keep things on topic.

Yifu, great information. That is the first time I have seen such concise information. Was there a single source for the information? When I read the Cree documentation it didn't mention all those details.


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## bose301s

yifu said:


> Ok here are the improvements...
> -Die shrink of around 10%
> -Die change to SiC (new process beginning with the XB-D)
> -Binning at 85 degrees celsius(used to be 25 degrees)
> -Removal of bond wires (so we can drive it to 6A without the wires melting:devil:
> -Efficiency increase of 10% (at 85C)
> -Substantial cost reductions (half the lumen per dollar cost)
> -Longer L70 lifetime
> -And dome is easier to remove...
> 
> I think it's a good upgrade.


A few points that are just blatantly wrong here. Cree has always used SiC wafers for their LEDs. XM-L2 is just the 3rd gen SiC product, but nothing fundamentally different on that front. Also, the bond wires are still there, in fact instead of 3 of them there are now only 2 which is the probable reason for the Vf of the XM-L2 being higher. What was removed were the current spreaders on the top of the chip and went to a new FC style.


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## yifu

Yes, i phrased it wrong, i meant a new SiC process which reduces cost, and yeah i meant current spreaders, which tended to melt when driven very hard, even though the phosphor could take more... Now the XML2 can put out nearly 1500 lumens at 6A with good heatsinking. I will rephrase everything
_-Die shrink of around 10%_
_-Die change to new SiC process (new process beginning with the XB-D)_
_-Binning at 85 degrees celsius(used to be 25 degrees)_
_-Removal of current spreaders and reduction in bond wires from 3 to 2 (so we can drive it to 6A without the wires melting_:devil: and the aspheric beam looks nicer
_-Efficiency increase of 10% (at 85C)_
_-Substantial cost reductions (half the lumen per dollar cost)_
_-Longer L70 lifetime_
_-And dome is easier to remove (personal experience) for more throw..._


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## uk_caver

Is the lumen-per-dollar point related to what it currently costs Cree to make one device compared to the other, or is it a bit of a spurious PR thing - a comparison over time between product costs or prices at launch, not between devices at the same point in time?

LEDs used to be more expensive, but all that seems relevant for a designer at the moment is what's currently available and what the current price/performance is, and maybe what is expected to happen in the near future.


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## PocketBeam

The spec sheets say 3000mA max current. Where did you find the 6A spec?


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## RoGuE_StreaK

BeastFlashlight said:


> I hope that the voltage requirements and drivers of XMLs stay compatible down thru the years because I'd really like to be able to simply swap out my LEDs on my custom lights as they improve.


As long as you are using constant current drivers then it shouldn't matter a damn, unless for some bizarre reason the Vf jumps massively. Most are decreasing substantially, which just means you'll run with the same current for longer before the driver gets out of regulation.



PocketBeam said:


> The spec sheets say 3000mA max current. Where did you find the 6A spec?


There is no spec; this is purely through people's experimentation, you'll find here that we see max limits as a challenge rather than a rule  Note that you need seriosly good thermal dissipation to do this kind of thing. Also the spec sheets are written with a mind of reaching thousands of hours runtime; most here will never run a flashlight anywhere near that long, so can afford to push the LED further than specced.


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## yifu

PocketBeam said:


> The spec sheets say 3000mA max current. Where did you find the 6A spec?


Good manufacturers of anything ALWAYs intentionally underrate their products, i.e. McClickys rated for 3A can take around 8A before melting, hard disks with MTBF of 1 million hours can almost always take more, a lift rated for 15 people can definitely take 50 or more before snapping:devil:. The 3A rating is just the conservative suggestion made by Cree for safe operation over tens of thousands of hours, the lumen increase after that is almost linear until 5A, which means that it can take a heck of a lot more.

We CPFers around here like to take things to the next level, for instance, the DEFT-X runs an XPG2 at double its 'max current' for nearly 800 lumens out the front and half the stuff on the B/S/T are overdriven for example. The XML2 will output nearly 1700 lumens at a 6A driven current on a direct to copper setup, and if that is then dedomed you will be looking at a 200% in lux over a 3A domed XML2 in the same light. Long term stability is an issue but after running a dedomed AND overdriven LED for hundreds of hours no loss showed up on a lux meter. After that time some new LED would have come up anyways so L70 lifetime is irrelevant for flashlight use.


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## pepperdust

also , color spectrum is different.


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## CfabStudios

Is this one of the smallest and most powerful chips manufactored to date?


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## StudFreeman

I thought both XM-L and XM-L2 employ 4mm^2 dice?


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## MechE1

yifu - how do you remove the dome?


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## AJ Botha

ROB21 said:


> So, does it generate the same amount of heat at the same lumen value?



More efficient means that more energy is converted to light, thus lowering the amount of heat generated.


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## AJ Botha

Wow so I wont break my LEDs if I push them over 3A? 
At 3A measured with a thermal infrared gun I measure 60 dC at most. Guess I can push them till they reach 85dC? 
@StudFreeman the XM L2 is 5mm X 5mm thus 25mm^2.


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## RoGuE_StreaK

Really depends on your heatsinking and how long you are going to be running them at a time. If you can get the heat out before it builds up then yeah you could likely push it further than 3Amps. Recommendation would probably be for a direct-to-copper MCPCB to try to get as much heat out and spread as efficiently as possible, then figuring out your heatsink; if your path from the LED heatpad to the heatsink is restricted, then no matter how good a heatsink you have you are going to have bottlenecking issues at these higher currents.
RE: needing a passive heatsink (other thread), you might need to investigate heatpipes, but they are expensive. Cheapest source is probably from computers, see if anyone isn't using their powermac anymore 

PS. From what I've read along the way you should take the IR gun readings with a grain of salt; can't remember the specifics though. Might be to do with not being able to get a reading of the actual junction?


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## AJ Botha

Does direct-to-copper MCPCB mean the conducting material is copper in stead of the aluminum one that I currently have? 
Yeah I dont really believe the IR gun either, when I put my finger on it I can clearly feel its more than 60 degrees C!


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## RoGuE_StreaK

Direct-to-copper is the latest craze going around here; not only is it a copper board instead of aluminium, the major point is that the LED's thermal pad is actually soldered directly to the copper, rather than onto an intermediary copper plane that is bonded to the underlying board. This bonding was a bottleneck. The theory (and seemingly tests bear it out) is that there is a much more direct and unrestricted thermal path which goes directly to a copper heatspreader (the board), meaning you have a big area to transfer your heat out of into your heatsink, meaning you could be able to suck out the heat before it builds up in the junction and is detremental to performance/longevity.

NB: the ideas have been tossed around here for several years, but only really recently have some manufacturers started mass-producing them, making it a hell of a lot cheaper; you can get them for about $2 each somewhere around here, as opposed to the previous custom machining costs of say $30 a pop.


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## DIWdiver

RoGuE_StreaK said:


> Direct-to-copper is the latest craze going around here; not only is it a copper board instead of aluminium, the major point is that the LED's thermal pad is actually soldered directly to the copper, rather than onto an intermediary copper plane that is bonded to the underlying board. This bonding was a bottleneck. The theory (and seemingly tests bear it out) is that there is a much more direct and unrestricted thermal path which goes directly to a copper heatspreader (the board), meaning you have a big area to transfer your heat out of into your heatsink, meaning you could be able to suck out the heat before it builds up in the junction and is detremental to performance/longevity.


To be more specific, it isn't just the bonding, it's the thin layer of fiberglass insulation (it's actually a very thin circuit board) that causes the thermal 'bottleneck'. The conductivity of FR4 (commonly used PCB material) is about 1400 times less than copper, and about 700 times less than aluminum, so even a very thin layer has a big impact.


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## AJ Botha

So with a direct to copper board the insulating layer will only be beneath the solder pads and not beneath the heat pad in the middle? Sounds awesome, doubt that I can get those reasonably priced in South Africa though!


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## RoGuE_StreaK

AJ Botha said:


> So with a direct to copper board the insulating layer will only be beneath the solder pads and not beneath the heat pad in the middle? Sounds awesome


Yes. 'tis.



AJ Botha said:


> doubt that I can get those reasonably priced in South Africa though!


Not _in_ South Africa, but someone here (vestureofblood I believe?) is selling them for extremely reasonable prices, with only a couple of bucks shipping anywhere in the world. In fact, the pricing is much much better than actually ordering direct from the manufacturer!? :huh:


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## monkeyboy

yifu said:


> -Die shrink of around 10%



That's the first I've heard of this. Got any links to prove that?


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## Kevin Doe

Can anyone make a generalization of how a smaller die would effect the light output from an optic. For example, if you have an 10 degree FWHM optic on an XM-L, how would you expect the light output through the same optic with and XM-L2 with a smaller die to change?


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## tstartrekdude

The entire beam profile will be 10% smaller and given the same light output from the die it will have 10% higher lux. Both of which are basically unnoticeable unless directly comparing the two side by side, and even then you would have a very hard time differentiating the two. 

This would apply to any optical system you are using.


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## verysimple

But those won't come out until later next week..



BeastFlashlight said:


> And hopefully XML3 will be 20% brighter than XML2, than XML4 will be 20% brighter than XML3...


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## jakepen

*Cree xml vs cree xml2.*

What's the difference, and what do I look for to tell the difference between the two? 

Sent from my SCH-I545 using Tapatalk


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## RoGuE_StreaK

*Re: Cree xml vs cree xml2.*

v2 has a silver board, v1 has green


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## samgab

*Re: Cree xml vs cree xml2.*



jakepen said:


> What's the difference, and what do I look for to tell the difference between the two?
> 
> Sent from my SCH-I545 using Tapatalk



Difference in performance, eg:






And in appearance, at a glance; an XM-L emitter has 3 bond wires and 4 visible segments, whereas an XM-L2 has 2 bond wires and no visible segments.
It has the same mechanical and optical footprint, however.


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## RoGuE_StreaK

*Re: Cree xml vs cree xml2.*

I haven't seen a comparison layed out like that before, it's... a bit of a *****?! If you work off a CC basis, then the Vf has actually _increased_, which is NOT where I want it to go; drive it at the same current as you used to and you now need more voltage on hand. Inversely if you look at the lumens, you could say roughly that you are getting the same lumens at the same Vf, but with a lower current. A little bit of a catch 22, kinda increasing efficiencies but not in a way that lets you drive it harder?


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## LEDAdd1ct

*Re: Cree xml vs cree xml2.*



RoGuE_StreaK said:


> I haven't seen a comparison layed out like that before...



The screenshot above is from the Cree tool.

Usage of the tool has answered many of my questions without posting and stopped
me from starting countless threads.

In my opinion, the two best tools are:

Cree Tool

Runtime Tool


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## samgab

*Re: Cree xml vs cree xml2.*

Oh yeah, thanks LEDAdd1ct, I should have posted a link to -and mentioned- my source, the Cree PCT. But thanks for posting those two links. They are very useful tools.


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