# Cree Xp-G3 LED



## mds82 (Mar 14, 2016)

Update - its official, cree released this

Hi All,
I was just browing PCT.cree.com and saw there is a Cree XP-G3 LED. I dont know if this is a typo as there are no specs anywhere about this new LED. Attached is a screenshot at the highest bin. 

@ 350mA it produces 191 lumens, 193 lm/w, Vf is 2.83 and 0.99 watts used


----------



## mds82 (Mar 15, 2016)

*Re: Cree Xp-G3 LED ??*

well its no longer there today, and the xp-g2 configuration doesn't work, so maybe just a problem on their end


----------



## TexLite (Mar 17, 2016)

*Re: Cree Xp-G3 LED ??*

Hmmm, interesting. That's an awful lot of info to have for a simple mistake. The current XP-G2 datasheet doesn't even list an S5 bin, highest is S4.

Maybe it's an upcoming product that was made "live" early by mistake, one can dream right?

And wouldn't that be approaching the theoretical top end of LED efficiency? I thought I remembered reading in a paper somewhere a few years ago the theoretical top end was in the 200-250 lm/w range? Or am I mistaken?

XP-G2 is working in the selector today, but seems sluggish.

Regardless, cool find!

-Michael


----------



## degarb (Mar 20, 2016)

*Re: Cree Xp-G3 LED ??*

I don't see people here commenting on the Cree March 6, 2016 press release saying that the xpg and XML is getting, just got, %10 brighter. The release didn't elaborate.


----------



## TexLite (Mar 21, 2016)

*Re: Cree Xp-G3 LED ??*

XM-L3?

You've been here as long as I have, my favorite sub-forums have always been Modified and LED's, there doesn't seem to be as much "activity" here as there was before my recent hiatus, is it just me or has interest in those areas fallen off?

And 10% would indeed put output in the next flux bins, but why the -G3 moniker? 

-Michael


----------



## monkeyboy (Mar 25, 2016)

*Re: Cree Xp-G3 LED ??*

There's a press release dated 8th March 2016 specifically saying that the XP-G2 and XP-L are now up to 9% brighter. This suggests to me that this might just be the improvements we've seen in the last few months with higher flux bins.
No mention of an XP-G3 though so could have been a typo as the XP-G2 also goes up to S5 [172] on the Cree characterisation tool (which isn't working anymore).


----------



## ShineOnYouCrazyDiamond (Mar 25, 2016)

*Re: Cree Xp-G3 LED ??*

If they came out with a XP-G2/3 HI version I'd be interested. Otherwise, IMO, the XP-L HI has surpassed the XP-G line in terms of output, current handling and tint quality. Any XP-G based light I've upgraded to a XP-L HI has a smoother beam, a bit more throw, less beam artifacts towards the edges, no chromatic aberration, higher current handling and overall better tint.


----------



## tab665 (Mar 25, 2016)

*Re: Cree Xp-G3 LED ??*



ShineOnYouCrazyDiamond said:


> If they came out with a XP-G2/3 HI version I'd be interested. Otherwise, IMO, the XP-L HI has surpassed the XP-G line in terms of output, current handling and tint quality. Any XP-G based light I've upgraded to a XP-L HI has a smoother beam, a bit more throw, less beam artifacts towards the edges, no chromatic aberration, higher current handling and overall better tint.


+1 on a XP-G HI for insane throw. i agree with your opinion of the XP-L HI. i had a prometheus alpha upgraded from an XM-L to the XP-L HI. has a nice even tint across the beam, no random green corona or purple spill.


----------



## lucca brassi (Mar 26, 2016)

*Re: Cree Xp-G3 LED ??*

XP-L leds sometimes throw wired shadows due side cut dome ( special with lens )


----------



## ShineOnYouCrazyDiamond (Mar 26, 2016)

*Re: Cree Xp-G3 LED ??*



lucca brassi said:


> XP-L leds sometimes throw wired shadows due side cut dome ( special with lens )



Agred - not much different than the XM-L2. And they don't always work in XP-G reflectors even though the base is the same. That's why I was referring to the HI version which is great.


----------



## mds82 (Apr 12, 2016)

*Re: Cree Xp-G3 LED ??*

Yup its official now, Cree released it today


----------



## mk2rocco (Apr 12, 2016)

*Re: Cree Xp-G3 LED ??*

It looks like they have a bunch of 90+CRI emitters coming out!


----------



## PapaLumen (Apr 12, 2016)

*Re: Cree Xp-G3 LED ??*

So they did... XP-G3. - http://www.cree.com/News-and-Events...uces-the-Next-Generation-of-XLamp-XPG-Platfor

Specs - http://www.cree.com/News-and-Events...spx?_id=09A63299CEB2415BB435E17DDB55BE57&_z=z

http://www.cree.com/~/media/Files/Cree/LED-Components-and-Modules/XLamp/Data-and-Binning/dsXPG3.pdf

Ooh, max drive current increased to 2A for 777lumens...


----------



## The_Driver (Apr 13, 2016)

*Re: Cree Xp-G3 LED ??*

Not a very interesting LED (*EDIT:* for throwers) at the moment. 

At 350mA and 85°C the new XP-G3 S5 is only 4.9% more efficient than a XP-G2 S4. That is less than the usual 6% between different XP-G2 Bins. 
The thermal resistance was lowered from 4°C/W to 3°C/W. This is the reason for the higher rated maximum current of 2A. It might translate to better performance at 5A (roundabout the maximum a properly cooled XP-G2 will take).

The forward voltage at 1.5A and 85°C has been lowered from 3.1V to 2.99V. That's nice, but not really a big improvement, especially when you consider that recently produced S4-Bin XP-G2 emitters seem to have extremely high Vfs lately when overdriven.

When comparing the pictures in the datasheets it seems to me like the XP-G3 has a larger DIE compared to the XP-G2. Even small changes in the size of the DIE have a large influence on the luminance which is what cause throw (together with reflector diameter). The DIE also seems to be connected to the dome in a special way which might make de-doming hard or even impossible. Both of these things combined might cause the XP-G3 to not be the successor of the XP-G2 for powerful, modded Throwers.


----------



## monkeyboy (Apr 13, 2016)

*Re: Cree Xp-G3 LED ??*



The_Driver said:


> When comparing the pictures in the datasheets it seems to me like the XP-G3 has a larger DIE compared to the XP-G2. Even small changes in the size of the DIE have a large influence on the luminance which is what cause throw (together with reflector diameter). The DIE also seems to be connected to the dome in a special way which might make de-doming hard or even impossible. Both of these things combined might cause the XP-G3 to not be the successor of the XP-G2 for powerful, modded Throwers.



The die doesn't look any bigger to me, just that the phosphor is overlapping the edges of the die.

EDIT: It says in the press release that the lumen density is improved which means more lumens/mm^2 die area.


----------



## scs (Apr 13, 2016)

*Re: Cree Xp-G3 LED ??*

There are discussions at budgetlightforum about recent XP-G2s using larger dies.


----------



## The_Driver (Apr 13, 2016)

*Re: Cree Xp-G3 LED ??*



monkeyboy said:


> The die doesn't look any bigger to me, just that the phosphor is overlapping the edges of the die.
> 
> EDIT: It says in the press release that the lumen density is improved which means more lumens/mm^2 die area.



One needs to look really, really closely at the pictures. If the side length of the DIE is 0,05mm longer for example it already has a profound effect on the luminance (cd/mm^2). Luminance is what actually determines throw. 

Lumens density refers to the lumens per package size of the led (3,45mm*3,45mm). The XP-L for example has a higher lumen density than the XP-G2. Same size LED, but more lumens. This is what Cree means when they use that term. Higher lumens density allows manufacturers of lighting products to make their lights smaller for a given brightness (or brighter for a given size). 

The luminance of the LEDs is not given in Cree datasheets unfortunately. It needs to be measured. sma in the German TLF forum has done this with a lot of different LEDs and also other light sources. See here. He has also tested a XP-G2 S4 seperately. Because of the bigger DIE the luminance was not much higher (only 3.5%) compared to a three year old XP-G2 R5. It should have been around 18% higher.

Size of different de-domed XP-G2 DIEs:
XP-G2 R5 from 2013: 1.66mm^2
XP-G2 S4 from 2015: 2.13mm^2 - 2.22mm^2
Both are precisely measured and the size of the non-glowing bond wires (0,3mm^2) has been subtracted. The XP-G2 S4s from last year are 30% larger compared the older ones from 2012/2013!


----------



## clemence (Apr 13, 2016)

*Re: Cree Xp-G3 LED ??*

Hi all,

I think it's not developed only for the LPW, CPL, or brute output. If you look carefully further down the variants in data sheet, the XPG3 is prepared to beat the Nichia 219 market.
minimum 90CRI for 2700K up to beyond 6500K!!! Now, this is awesome!
Now we have wider selection of high CRI, not limited to just below 3000K as before.

Note: They're updating the www.pct.cree.com database. As per this post, the XPG3 is no longer listed there. Should be temporary. The XPG2 listing also has errors loading the data.

Cheers,
Clemence


----------



## psychbeat (Apr 14, 2016)

Looking forward to someone testing some samples- hopefully up to or beyond 5amps


----------



## TexLite (Apr 15, 2016)

*Re: Cree Xp-G3 LED ??*

Nice scoop mds82!

The new High CRI versions do look interesting, I've got some Streamlights they should work well in.

-Michael


----------



## degarb (Apr 15, 2016)

*Re: Cree Xp-G3 LED ??*

"By leveraging key elements of Cree’s SC5 Technology™​ Platform"

Need a translator here. Double speak alert-but-maybe not?.....I am guessing from here, that the sc5 was introduced in Oct 2014-1.5 yearish ago. Is it just a lower thermal resistance technology? Was it only used, for last 1.5 years, in the XHP, but not in the XPL or XPG2? When they add to the xpl, will it become the xpl2 or xpl3? And how soon? What about the xml2?


----------



## The_Driver (Apr 15, 2016)

*Re: Cree Xp-G3 LED ??*



degarb said:


> "By leveraging key elements of Cree’s SC5 Technology™​ Platform"
> 
> Need a translator here. Double speak alert-but-maybe not?.....I am guessing from here, that the sc5 was introduced in Oct 2014-1.5 yearish ago. Is it just a lower thermal resistance technology? Was it only used, for last 1.5 years, in the XHP, but not in the XPL or XPG2? When they add to the xpl, will it become the xpl2 or xpl3? And how soon? What about the xml2?



Here (or here) is a nice explanation from Cree. The LEDs basically just tolerate higher temperatures. This allows them to put bigger DIEs in smaller packages without them overheating. These high-lumen LEDs can replace many smaller LEDs (reducing costs) and also use smaller heatsinks (because higher temperatures are no problem). In end they make the design of lights much simpler. 

It says here that the XP-L (and XP-L HI) and the newer Bins of the XP-G2 use the SC5 technology.


----------



## tab665 (Apr 18, 2016)

*Re: Cree Xp-G3 LED ??*



clemence said:


> Hi all,
> 
> I think it's not developed only for the LPW, CPL, or brute output. If you look carefully further down the variants in data sheet, the XPG3 is prepared to beat the Nichia 219 market.
> minimum 90CRI for 2700K up to beyond 6500K!!! Now, this is awesome!
> ...


this ought to be quite the wildcard in the cool vs neutral vs warm vs HCRI endless debates.


----------



## clemence (May 20, 2016)

*Re: Cree Xp-G3 LED ??*

Cree has done updating the XPG3 database. You can now comparing the XPG3 to other Cree emitters at www.pct.cree.com
A great news: XPG3 sells lower than the XTE! XTE is well known as the cheapest XP emitters until now (lumen vs. price). With such amazing tint, higher current capability, and high CRI available XPG3 will soon goes mainstream. FYI, all the XPG3 CRI90 variants reached the R3 bin.
In terms of colour quality XPG3 is much better than XPL. S5 bin XPG3 also more efficient than V5 bin XPL up to 670mA.

Cheers,
Clemence


----------



## degarb (May 21, 2016)

*Re: Cree Xp-G3 LED ??*



ShineOnYouCrazyDiamond said:


> If they came out with a XP-G2/3 HI version I'd be interested. Otherwise, IMO, the XP-L HI has surpassed the XP-G line in terms of output, current handling and tint quality. Any XP-G based light I've upgraded to a XP-L HI has a smoother beam, a bit more throw, less beam artifacts towards the edges, no chromatic aberration, higher current handling and overall better tint.



pct.cree.com now has 346ish lumens for xpg3 v. 311 for the xpl hi. Leapfrog, until the new xpl, key elements of Cree’s SC5 Technology™​ Platform, the XP-L, is released. I wonder what the *name* will be for the new xp-l...??? If they name it the xpl2, people will think the xml3 is better. If they call it, "the xpl3", then they skipped the xpl2 monicker.

I am seeing verification that the needed heat sink goes way down once the 200lpw is hit. I am seeing a noticeable, measurable, heat difference in my three latest neutral led builds: xpl hi at 155lpw, v. xpl v6 at 187lpw, v. 138 ish lpw xml2-- all, at 700 ma. So, I am going holding my breath for the 200lpw at 700 ma, xpl v7. Hope no lasting health side effects on my vision. Though, I really don't like how yellow these 4700K all are; I may go 5500K next time.

As I recall with recent article, 240 lpw theoretical maximum for a neutral, low 300s for the cool. Probably 200 for warm? Though California and Cree are vowing to concentrate of reproducing the horrid, soul sucking, innervating incandescent yellow experience.


----------



## recDNA (May 21, 2016)

*Re: Cree Xp-G3 LED ??*



degarb said:


> pct.cree.com now has 346ish lumens for xpg3 v. 311 for the xpl hi. Leapfrog, until the new xpl, key elements of Cree’s SC5 Technology™​ Platform, the XP-L, is released. I wonder what the *name* will be for the new xp-l...??? If they name it the xpl2, people will think the xml3 is better. If they call it, "the xpl3", then they skipped the xpl2 monicker.
> 
> I am seeing verification that the needed heat sink goes way down once the 200lpw is hit. I am seeing a noticeable, measurable, difference in my three latest neutral led builds: xpl hi at 155lpw, v. xpl v6 at 187lpw, v. 138 ish lpw xml2-- all, at 700 ma. So, I am going holding my breath for the 200lpw at 700 ma, xpl v7. Hope no lasting health side effects on my vision. Though, I really don't like how yellow these 4700K all are; I may go 5500K next time.
> 
> As I recall with recent article, 240 lpw for a neutral, low 300s for the cool. Probably 200 for warm? Though California and Cree are vowing to concentrate of reproducing the horrid, soul sucking, innervating incandescent yellow experience.


I don't necessarily agree but I love the way you expressed that opinion. "Soul-sucking" great stuff! LOL


----------



## lyyyghtey (May 25, 2016)

*Re: Cree Xp-G3 LED ??*



recDNA said:


> I don't necessarily agree but I love the way you expressed that opinion. "Soul-sucking" great stuff! LOL



At first glance I was worried California was starting to demand color temperature preference, if not legally then at least by what they decided to focus on. I researched a little bit, and as I understand it (from various threads found on construction/remodel type fora) Californians had been banned from using 2700K in certain rooms because it wasn't efficient enough. (even the LEDs). So maybe this is a push to repeal that legislation as LED tech has progressed adequately now to finally smash through those efficiency barriers!

I don't personally have a color temperature preference that holds true for most situations. I use 6500K in my home just as much as 2700K (and I've had to CTO-gel 2700K 90+ CRI LEDs to get them down to 1900K for lack of affordable/dimmable LED alternatives!)

I usually EDC 2700K AND 5000K flashlights, and I'd go even cooler if there were reasonable options available at 90+ CRI. (Unfortunately I don't consider lots of little .5W or smaller SMT LEDs nor a 20V COB engine to be reasonable options for a torch! ) 

Sometimes 2700K is "soul sucking"ly horrid, and at other times 5000K is hopelessly frigid. It just depends on my needs at the time. 

I'm talking about aesthetically pleasing lighting here. Other concerns will of course dominate when you're lighting a warehouse or a city street grid and it would probably be too expensive and wasteful to use 90 CRI lighting regardless of its color temp.

I think at both ends of the CCT scale, some of the perceptions of lighting misery could be caused by inadequate CRI. Even a 80 CRI 2700K lamp can look excessively yellowish, and a 6500K source at 80CRI can appear yellow-greenish or at least lacking in reds. Sure, your eyes/brain can accommodate and tune out the deficiency over time, but it's never gonna be as good as it could be. 

Before you argue 6500K wouldn't have much red anyway, try illuminating a scene of richly varnished wood using just the un-glass-window-tinted sky light from the north before the sun rises (well over 6500K) and then try the same thing with your artificial 6500K or above source. Based on the 6500K or cooler sources typically available you're likely to be sadly disappointed! (that poor little 613 nm "red" band in triphosphor fluorescent has no hope of doing what that north sky light just did)

Not that it's even easy to FIND a 6500K LED bulb in a brick-and-mortar. Or a 4000K one for that matter, let alone in high-CRI variety! :shakehead:scowl:

So bringing it back to the OT, basically YES, I'm REALLY hoping these 90+ CRI 6500K XP-G3s come to fruition!!! :thumbsup::thumbsup::thumbsup: And I wouldn't mind if they came out with a 10,000K or 15,000K variant at 90+ CRI either!!!

OK, I admit it, I'm just weird. Enough wishful hoping.


----------



## recDNA (May 25, 2016)

I like 5000k 219b 90+ CRI and fortunately Nichia has one. XP-G3 will likely be more efficient but if it below 4500k or above 5500k I have no interest. I know what I like.


----------



## write2dgray (May 25, 2016)

I'm with you recDNA, I also still prefer the HiCRI 5000K 219B over all other options I've tried to date.


----------



## TexLite (May 27, 2016)

*Re: Cree Xp-G3 LED ??*



lyyyghtey said:


> At first glance I was worried California was starting to demand color temperature preference, if not legally then at least by what they decided to focus on. I researched a little bit, and as I understand it (from various threads found on construction/remodel type fora) Californians had been banned from using 2700K in certain rooms because it wasn't efficient enough. (even the LEDs). So maybe this is a push to repeal that legislation as LED tech has progressed adequately now to finally smash through those efficiency barriers!
> 
> I don't personally have a color temperature preference that holds true for most situations. I use 6500K in my home just as much as 2700K (and I've had to CTO-gel 2700K 90+ CRI LEDs to get them down to 1900K for lack of affordable/dimmable LED alternatives!)
> 
> ...



Even some "High CRI" LEDs are sadly lacking in their R9 value, which is what you're illustrating. There are a few other bands missing too, but the R9 seems to be the prominent or noticeable IMO.

-Michael


----------



## TexLite (May 27, 2016)

*Re: Cree Xp-G3 LED ??*



degarb said:


> I am seeing verification that the needed heat sink goes way down once the 200lpw is hit. I am seeing a noticeable, measurable, heat difference in my three latest neutral led builds: xpl hi at 155lpw, v. xpl v6 at 187lpw, v. 138 ish lpw xml2-- all, at 700 ma. So, I am going holding my breath for the 200lpw at 700 ma, xpl v7. Hope no lasting health side effects on my vision. Though, I really don't like how yellow these 4700K all are; I may go 5500K next time.
> 
> 
> As I recall with recent article, 240 lpw theoretical maximum for a neutral, low 300s for the cool. Probably 200 for warm?




Here's an interesting graph illustrating what you're seeing. The graph uses 350 LPW, and as interesting note here, Cree has already surpassed 300 LPW at 5150k, so I suppose it depends on your personal definition of "Neutral". Officially, 5000K and below is considered Neutral.

It is still cool to see the relationship between the two.







Look at the drop in waste heat going from 200 LPW to 250 LPW, doesn't seem like that much of an increase in efficiency, but the waste heat is halved.

-Michael


----------



## degarb (Jun 6, 2016)

*Re: Cree Xp-G3 LED ??*



TexLite said:


> Here's an interesting graph illustrating what you're seeing. The graph uses 350 LPW, and as interesting note here, Cree has already surpassed 300 LPW at 5150k, so I suppose it depends on your personal definition of "Neutral". Officially, 5000K and below is considered Neutral.
> 
> It is still cool to see the relationship between the two.
> 
> ...



Saving this gif to google drive.

I need to correct myself: after v6, the Cree xp-l goes to w2 and w3 bin. I don't see the lpw for the w2, on the spec sheet or the pct.cree.com. I see the w2 bin on Alibaba, and in two lights on the market. Though, I doubt these leds employ the newest SiC technology, like the xpg3-yet. Just bright, cool tint leds.


----------



## lyyyghtey (Jun 17, 2016)

*Re: Cree Xp-G3 LED ??*

That chart is quite interesting! I've seen calculations of this sort before but never a full chart. It's quite amazing how rapidly the waste heat and total power go down as efficiency approaches max theoretical. I can't remember, does anyone know at what CRI that 327 LPW was calculated? (Theoretically a more greenish-tinted light, with a lower CRI, would have a higher LPW since 555nm green maxes out at over 600 LPW as I recall from a few years back).

My other thought about that chart is that it would appear it was written while maximum allowable junction temperatures were a fair bit lower than they are now (and/or with higher junction-to-ambient), a snapshot of LED tech at the time perhaps. Either that or they're shooting for 50,000 hours life or something, which few manufacturers seem to actually do.


Regarding light preferences, although I don't have a preference which always covers every situation, I do generally prefer 5000K Nichia 219b hi-CRI for most flashlight tasks (and some home uses as well). That said, I would still very much like to carry a _supplementary_ 10,000K or 15,000K or 20,000K light _with 90+ CRI_. (see, there's my weirdness creeping in again, right?)

Yes I'm thinking specifically about the R9 values here, since it's the most noticeable deficiency of a lot of lower-CRI lighting as well as evidently being the easiest to solve (at least with LEDs). That said, I would like it if more manufacturers released violet-pump whites suitable for torches so that more of the blue band colors could be filled in/that tall blue spike squashed out, and especially the aqua bumped up a bit more.


----------



## markr6 (Jun 17, 2016)

*Re: Cree Xp-G3 LED ??*



lyyyghtey said:


> Not that it's even easy to FIND a 6500K LED bulb in a brick-and-mortar. Or a 4000K one for that matter, let alone in high-CRI variety! :shakehead:scowl:



I gave up on stores and went to amazon. Hyperikon 4000K @ 90+ CRI...and CHEAP! About $4/bulb for the 4-pack. Pretty darn amazing!



recDNA said:


> I like 5000k 219b 90+ CRI and fortunately Nichia has one. XP-G3 will likely be more efficient but if it below 4500k or above 5500k I have no interest. I know what I like.



Same here!


----------



## easilyled (Jun 21, 2016)

*Re: Cree Xp-G3 LED ??*



ShineOnYouCrazyDiamond said:


> If they came out with a XP-G2/3 HI version I'd be interested. Otherwise, IMO, the XP-L HI has surpassed the XP-G line in terms of output, current handling and tint quality. Any XP-G based light I've upgraded to a XP-L HI has a smoother beam, a bit more throw, less beam artifacts towards the edges, no chromatic aberration, higher current handling and overall better tint.



Sean, have you had any experience of the XHP35-HI just to confuse matters further.

The XHP35-HI is also a factory domeless emitter (like the XPL-HI). I'm not sure which has the smaller die, but the XHP35-HI is the emitter of choice in the ACEBEAM K70 and using only a single emitter in this light, the output is rated at 2600 lumens and the distance of the beam is rated at1300 metres.

So it appears that the XHP35-HI is capable of greater output than the XPL-HI and probably similar or better throw?


----------



## ShineOnYouCrazyDiamond (Jun 21, 2016)

*Re: Cree Xp-G3 LED ??*

My only experience with the XHP35 HI is in the ZL SC600 MkIII. In that light it does a great job. Problem is the drive voltage required. It's a 12 volt LED and I haven't been able to find a single driver which can boost a single 18650 cell to that level. ZL did some magic with their implementation.


----------



## easilyled (Jun 21, 2016)

*Re: Cree Xp-G3 LED ??*



ShineOnYouCrazyDiamond said:


> My only experience with the XHP35 HI is in the ZL SC600 MkIII. In that light it does a great job. Problem is the drive voltage required. It's a 12 volt LED and I haven't been able to find a single driver which can boost a single 18650 cell to that level. ZL did some magic with their implementation.



Ah! That explains why its not so commonly seen in single-cell lights then. It certainly seems like a breakthrough led in terms of its selection for larger Search & Rescue type lights like the Acebeam K70 and provides a great balance of throw and output.


----------



## clemence (Jun 21, 2016)

*Re: Cree Xp-G3 LED ??*

Soon it will replace some already known good throwers out there, I heard the birds.... 
Yes, it has bigger hotspot compared to XPL HI but the lumen density is almost double. The best thing about XHP35 HD/HI is the wider selection of tint and CRI. XPL tend to shift the tint too easily (from greenish to cyanish as the current rise), let's hope this XHP35 has better tint stability.
This small 3535 chip size with huge lumen capability will be a killer combo in big TIR optics. bigger hotspot size, little to none spill, with almost the same INTENSITY will shine bigger area for more useful search and rescue flashlights.


----------



## jtr1962 (Jun 21, 2016)

*Re: Cree Xp-G3 LED ??*



lyyyghtey said:


> That chart is quite interesting! I've seen calculations of this sort before but never a full chart. It's quite amazing how rapidly the waste heat and total power go down as efficiency approaches max theoretical. I can't remember, does anyone know at what CRI that 327 LPW was calculated? (Theoretically a more greenish-tinted light, with a lower CRI, would have a higher LPW since 555nm green maxes out at over 600 LPW as I recall from a few years back).
> 
> My other thought about that chart is that it would appear it was written while maximum allowable junction temperatures were a fair bit lower than they are now (and/or with higher junction-to-ambient), a snapshot of LED tech at the time perhaps. Either that or they're shooting for 50,000 hours life or something, which few manufacturers seem to actually do.
> 
> ...


Actually I'm the one who made that chart-way back in 2007. I'm glad people are still finding it useful nearly 9 years later! I took 330 lpw as a rough guide for the LER of LEDs at the time. Nowadays I'd say anything with decent color rendering will have a LER closer to 300 lpw for high CCTs, or even as low as 250 lpw for 2700K or 3000K.

And yes, the heatsinking requirements were based on the more conservative maximum allowable junction temperatures at the time. Nowadays it seems we've nearly reached the point where MCPCBs often provide all the heatsinking you need in 40W or 60W retrofits.

Don't post much here anymore but I saw this thread and wanted to address the questions on my chart.


----------

