Cree XD16 measurements

Flashlight Modding and DIY Parts
1

I was pretty excited about this LED and the possibility of making customized multi-die emitters. I ordered some from Arrow electronics. Part number: XD16AWT-H0-0000-00000BJE3. Should be S2 flux bin. I measured the output, forward voltage, and resulting intensity in a flashlight.

I made a makeshift MCPCB out of 1.6mm thick copper. I glued two pieces of the copper together with JB weld so that there was a small gap. To electrically isolate the two pieces from the shelf I used a couple thin strips of kapton tape on the bottom of the board.

Output measurements:
I measured the lux above the LED with the lux meter 0.59m from the LED. Assuming the angular light distribution is that of a Lambertian emitter I can calculate the total lumen output if I know the luminous intensity (cd) above the LED. I explain this more in this thread, and it seems to be consistent with other users’ measurements of the LEDs. The below lumen numbers are calculated using this method. I stopped the measurement at 5A because I wanted to save it for other measurements.

The output is lower than I hoped. The good news is that the whole surface of the LED appears to be lit uniformly. I don’t know if the whole area is covered by the actual die, but it did not look like the outer parts were any dimmer (like with the nichia E21A). So I think an array of these really would look like one gigantic seamless die. I did notice some blue light escaping out from the side of the package, similar to other cree flip chip LEDs if the side-phosphor is removed.

I put the LED in an eagle eye X6 and measured the beam intensity at 4A. Unfortunately the number is a bit disappointing at 51.5Kcd measured at 6.78m. The LED was in near perfect focus.

I was really excited to make a 3x3 array of these, but the performance will not be nearly as good as I hoped. The efficiency seems to be not that great, and the effective luminance is also not high, which would have been an advantage over XHP50.2 and XHP70.2. Now I’m not sure if I will continue with the 3x3 array. I hope others will measure the XD16 to make sure my measurements are not far off.

Update:
I was suspecting that the die does not reach to the end of the package so I scraped the phosphor off one to see. With my calipers, the package is 1.60mm across, and the die is 1.38mm across.

2

Thanks for posting your results… I always like reading about new LEDs…

3

Excellent info you have posted up EasyB. Thanks for the testing. :+1:

4

Thanks for the testing mate!
Its a shame it did not perform like we thought it would.
It looks different to the XPL-HI?

5

Its a very small die compared to other LEDs.

6

I’m disappointed with the performance mostly because I had high hopes for this LED. A 3x3 array would actually have comparable performance to a dedomed XHP70.2. At 12A (6V) the dedomed XHP70.2 does about 65 cd/mm^2 (I present you with Giggles, the most hardcore BLF thrower in the World. - #101 by Texas_Ace) and should output around 7000 emitter lumens (after a 10% loss from dedoming). At the equivalent current with the 3x3 XD16 array each LED is seeing 2.67A, so 6100 emitter lumens. The effective luminance at 4A in the X6 was 83 cd/mm^2, so at 2.67A it would be 64 cd/mm^2. So the 3x3 array would have comparable performance, but not as good efficiency, as the dedomed XHP70.2 and could be made 3V if one wanted.

That being said, it will be a lot of work to make a 3x3 array at this point, and I’m not sure the result would be good enough to warrant the work.

7

Thanks for testing! That is a disappointment. If one would even question your method (looks good!), the performance in the X6 tells all there is to know (and that the measured numbers must be close): for flashlight use this led does not beat what is out there already, both in output and throw.
:frowning:

8

I’ve decided I will go ahead and try to make the 3x3 array and put it in an emisar D1S. I already bought some supplies to do it and I’ve been wanting to do something with a D1S. It should pull around 24A from a high drain 18650 and do about 5500 lumens OTF and 83Kcd.

The performance might increase a bit when in array form, which it seems is the intended purpose of these LEDs. The amount of blue light escaping out the sides of a single die is significant, and I figure most of this light will become recycled and used to pump phosphor in neighboring dies in the 3x3 array. This would increase the output and luminance.

9

This is very odd. According to Cree’s PCT tool, this emitter is performing like an r2 or r3 bin. Lumen values are about 20% lower than s2 specs between one and two amps.

10

Maybe EasyB is onto something with the light recycling in an array, but I’d be quite surprised if they changed binning procedure and didn’t annotate that.

11

Also, how is the tint and beam pattern? Does that blue leakage make it into the beam?

12

I also noticed that it was below the cree spec for this bin. At 1A I measured 320 lumens so about 15% lower than the spec’ed 365 lumens.

The measurements I did to investigate the XPG3 (The XP-G3 and the mystery of the disappearing luminance) are relevant here. The XPG3 has the similar flip chip design. I measured the candela above the die just sliced and after I scraped all the phosphor from the area to the sides of the die. As in this measurement the candela above the die is proportional to the total lumen output. There is 15% decrease in output when I scrape all the phosphor off, allowing the blue light to escape out the sides. That situation is similar to with the XD16 by itself or surrounded by other XD16s, so I might expect a 15% increase in output when n in array form.

13

Yes, there was a blue corona. It was sort of a strange tint and tint shift reminiscent of the XPG3.

I will look at the beam some more later, but I think the effective die size is actually 1.6 x 1.6mm, so the beam is a bit bigger than dedomed XPG2/3

14

Those DIY board is very similar to my “twig-light”.

Based on my research with Jensen567, I predict the performance would likely to get worse in tight packed array.
E21A designed with sidewall reflector to minimize photon cross talks, big problem in general luminaire when one need to put arrays in very tight space. Even with those side wall reflector, I couldn’t close the gap narrower than 0,3mm. This phenomenon was urban legend to me until all those measurements revealed the ugly truth.

This XD16 doesn’t have any barrier (hence the blue side spill), the cross talks could be even more severe. I guess you’ll get increased luminance at the expense of much lower current capability. This should not be a problem if throw is what you’re after (hopefully it can beat the black flat). As long as the luminance gain vs. max. current net to useful numbers.

Let’s hope we have something better than XPL HI. I’m really curious about it too. Looking forward to see the result.

- Clemence

15

I’m not familiar with photon crosstalk. I looked at some of your tests. Do you just mean the edges are heated more and burn when two dies are next to each other? It seems to me that problem could be more to do with the construction of the E21A and it’s problem with phosphor cooling?

I don’t expect the XD16 to beat the black flat or XPL HI in luminance. I would expect up to a 15% increase from what I measured above, which doesn’t put it that high.

16

under the same setup the gapless design maxed in 4,8A (Jensen tested up to 5,5A). Spaced by 0,2mm made no difference. But using the alpha board spaced at 0,4mm it peaked very close to 12A.
250% max current increase.

No it’s not about phosphor cooling. Yes, the phosphor in E21A is indeed hotter than average but it still productive up to 3,2A/die. While in gapless quadtrix (4xarrays) max current was limited to only 1,2A/die.

- Clemence

17

This very well could be important for the XD16, but the extent of the effect is completely dependent on the chip design and phosphor heating. For example the edges of the E21A phosphor are probably more susceptible to burning because they are farther from the contacts leading to less cooling. I’ll keep it in mind during testing.

18

Thanks for the test! Interesting…

19

Could you explain what you believe is the mechanism causing this phenomenon then?

20

You’ll find most of the information here:

- Clemence