There was no flux bin provided as it was a pre-production sample.
White LED lumen testing
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milkyspit
Flashlight Enthusiast
In fairness to the MC-E, the sample you're using for comparison is a markedly warmer tint using less efficient phosphors... a better comparison would involve a cool white MC-E of M-flux and similar color temp... my guess is that plus identical heatsinks would give the Cree at least a 20% better result, and more importantly, it's a far more valid comparison since test conditions would be more consistent in both cases.
Still, the Phlatlight did deliver a great showing, there's no disputing that! :naughty:
jtr1962
Flashaholic
I agree 100% here. Looking at my earlier tests with the cooler binned P7s I was obtaining roughly 62-63 lm/W when driven at the 16 watt level, or roughly 1000 lumens. Add another 5% or so for the better heat sink, and that would be about 1050 lumens. An M-binned MC-E would probably slightly outperform the P7 based on the relative performance of the XR-Es and P4s, so I'd guess 1100 lumens at 16 watts on the same heat sink as the SST-90. OK, the SST-90 still beats it, but at least it's not the LED equivalent of a shut out!
You have a definite talent for understatement.
My jaw was dropping to the ground by the time the SST-90 hit 10 amps, and begged for more. If this is the way LEDs are heading, then it's going be 
.
My jaw was dropping to the ground by the time the SST-90 hit 10 amps, and begged for more.
BTW I managed to buy the last two CST-90s that are confirmed to be the top bin. These use the same die as the one I sent you but the die is directly mounted to a large piece of solid copper! They are rated up to 13A but we both know it can handle a bit more than that.:naughty: Question is can you power it up that high?
jtr1962
Flashaholic
Cool! Is your question "Do I have a power supply capable of going past 13 amps?" The answer is I do, although nothing electronically regulated like the one I usually use when testing LEDs. However, all this is giving me incentive to make some sort of current regulated switching supply which I can attach to my main supply. The power supply I was using is a linear supply I built. It can put nearly 12 amps and about 15 volts into a load. It was made mainly for testing thermoelectrics. As you can imagine, the heat sink for the MOSFETs got pretty warm powering a low voltage, high-current load like the SST-90. I think my idea of making a switching current regulator powered by the main supply makes more sense. I'm figuring I could probably design it to go past 25 amps. If huge, single-die LEDs are part of the future, then I need a better way of powering them than I do now.
Hopefully after I finish a few days of work, I'll get started. I'll obviously be using a chip which uses external MOSFETs and probably synchronous rectification. It might be a bit of a pain to design, although I suppose I'll find a ready market here if I'm able and willing to mass produce them. Anyway, were you thinking of sending me one of the CST-90s to test? I looked at the data sheet for those. They look like 16 or 17 amps should be no problem.
HarryN
Flashlight Enthusiast
Wow - very nice work. I would love to see how the rebel, MC-E and Luminus parts work at 60C as well so we can estimate real world output. Is there any way to fit that info into your test plans?
jtr1962
Flashaholic
I'll try to do that as soon as I finish up this latest round of work I need to do (building 100 regulator boards for a customer). Hopefully in a few days.
The SST-90 especially should be easy to do. I just need cut the fan speed enough to keep the heat sink at 60°C. The other two parts will need active heating over most of their operating range (although the MC-E at higher currents should produce enough heat to keep the heat sink at 60°C).
Judging by your earlier post I was not sure if you were able to test at the higher range safely. I am not the electronic wizard you are so most of what you said went over my head. I am perfectly willing to send you the CST-90 although unfortunately like the other one I will need it back as I have plans for it. I also have an MC-E M bin for you to test. I have a special little test for it as well which I will PM you about. Thanks!
jtr1962
Flashaholic
Thanks for the compliments! The thread will keep going so long as I'm alive and there are LEDs to test. As for the XP-G, I have some R4s on the way from Cutter for a bike light project, and I'll certainly be testing one of them!
Hi JTR1962This link might help http://www.national.com/an/AN/AN-1937.pdf
Thanks very much for your testing of white LEDs. I have some Light of Victory 1 Watt 10mm, and 0.5 Watt 8mm (140 degree viewing angle) white LEDs. Can I send a few to you? I tried to send a private message, but was denied access for some reason.
jtr1962
Flashaholic
Thanks for the link. Interesting IC. Not sure if I'd want to use it however due to the weird input voltage requirements.
Thanks for the compliments. I'm glad you've enjoyed the thread!
PM privileges are only given after the first few posts, which is why you were unable to PM me. I might be interested in testing the 0.5 watt 8mm. I've already tested a few narrow beam 10 mm's however, so there is probably not much to be gained by testing another. Besides that, the very narrow beam angle emitters are a major pain to test.
jtr1962
Flashaholic
Cree XP-G bin R5 (acquired October 2009)
A package containing my XP-Gs arrived from Cutter today. I had ordered R4 bins but Cutter substituted R5s. Naturally, the first thing I did after opening the package was to set up my test jig. The R5 bin is specified as 139 to 148 lumens. Color temperature of my sample appeared to be roughly 6500K. The XP-G was rather difficult to set up for testing due to its form factor. I mounted it on a PCB I had made for Rebels. It was necessary to modify the board a bit due to the different pad layout. I then thermal epoxied this on to a brass tab which was bolted onto my test jig. I'll admit the thermal path could have been a little better, but it didn't appear to affect test results very much. Here are those results:
Beam angle is 125.4°, Vf at 350 mA was only 3.01 volts, output was 145.4 lumens (well within the R5 bin), and efficiency was an amazing 137.8 lm/W! Owing to the larger die size, output and Vf scaled very well. Vf at 700 mA was 3.17 volts, output was 265.3 lumens. The corresponding numbers at 1000 mA were 3.26 volts and 351.1 lumens. Output at 1000 mA relative to 350 mA was 2.415, a bit short of the roughly 2.48 in the spec sheet. However, I'll attribute this small difference to my fairly lousy thermal path. Despite this, output continued to rise with current well past 2 amps, peaking at 546.6 lumens at 2500 mA! My previous highest result for a single die normal-sized emitter was 436.7 lumens, also at 2500 mA, for a Cree XR-E R2 mounted on a heat pipe and copper block. I've little doubt the XP-G could break 600 lumens on a similar setup. Another amazing thing was that efficiency remained above 100 lm/W until 1200 mA. Even at 2000 mA it was 77 lm/W.
It has been mentioned that the XP-G's superior performance can be attributed solely to a larger die size, as opposed to a better die. My test results also indicate a superior die. This is evidenced by the higher peak efficiency of the XP-G, as opposed to the best-binned XR-Es. My best result for an XR-E was 148.3 lm/W at 20 mA. The XP-G peaked at 157.6 lm/W between 60 and 80 mA. The chart below is further evidence of this. The red line is a plot of lumens versus current for the XP-G. The white line is a plot of lumens versus current for two XR-E R2s in parallel. Two XR-Es in parallel roughly simulates the die size of the XP-G. Note that the XR-E R2s I tested mostly likely have the larger die size Cree was using, prior to switching over to a slightly smaller size, due to the fact that I tested them in June 2008. This makes the comparison valid. Note how the XP-G outperforms two XR-E R2s in parallel up to roughly 1700 mA. Above that the XR-Es have an edge owing to their superior thermal path (heat pipe and copper block as opposed to brass tab and thermal epoxy).
Also interesting to note is that the XP-G outperforms 4-die emitters such as the MC-E up to roughly 1500 mA. Even at 2000 mA the XP-G managed 528.7 lumens, while a K bin MC-E I tested only managed slightly more, 538.5 lumens, at 500 mA per die. Granted, an M-bin MC-E would do somewhat better, but even there the difference wouldn't be huge.
Overall, the XP-G is another quantum leap in performance from Cree.
A package containing my XP-Gs arrived from Cutter today. I had ordered R4 bins but Cutter substituted R5s. Naturally, the first thing I did after opening the package was to set up my test jig. The R5 bin is specified as 139 to 148 lumens. Color temperature of my sample appeared to be roughly 6500K. The XP-G was rather difficult to set up for testing due to its form factor. I mounted it on a PCB I had made for Rebels. It was necessary to modify the board a bit due to the different pad layout. I then thermal epoxied this on to a brass tab which was bolted onto my test jig. I'll admit the thermal path could have been a little better, but it didn't appear to affect test results very much. Here are those results:
Beam angle is 125.4°, Vf at 350 mA was only 3.01 volts, output was 145.4 lumens (well within the R5 bin), and efficiency was an amazing 137.8 lm/W! Owing to the larger die size, output and Vf scaled very well. Vf at 700 mA was 3.17 volts, output was 265.3 lumens. The corresponding numbers at 1000 mA were 3.26 volts and 351.1 lumens. Output at 1000 mA relative to 350 mA was 2.415, a bit short of the roughly 2.48 in the spec sheet. However, I'll attribute this small difference to my fairly lousy thermal path. Despite this, output continued to rise with current well past 2 amps, peaking at 546.6 lumens at 2500 mA! My previous highest result for a single die normal-sized emitter was 436.7 lumens, also at 2500 mA, for a Cree XR-E R2 mounted on a heat pipe and copper block. I've little doubt the XP-G could break 600 lumens on a similar setup. Another amazing thing was that efficiency remained above 100 lm/W until 1200 mA. Even at 2000 mA it was 77 lm/W.
It has been mentioned that the XP-G's superior performance can be attributed solely to a larger die size, as opposed to a better die. My test results also indicate a superior die. This is evidenced by the higher peak efficiency of the XP-G, as opposed to the best-binned XR-Es. My best result for an XR-E was 148.3 lm/W at 20 mA. The XP-G peaked at 157.6 lm/W between 60 and 80 mA. The chart below is further evidence of this. The red line is a plot of lumens versus current for the XP-G. The white line is a plot of lumens versus current for two XR-E R2s in parallel. Two XR-Es in parallel roughly simulates the die size of the XP-G. Note that the XR-E R2s I tested mostly likely have the larger die size Cree was using, prior to switching over to a slightly smaller size, due to the fact that I tested them in June 2008. This makes the comparison valid. Note how the XP-G outperforms two XR-E R2s in parallel up to roughly 1700 mA. Above that the XR-Es have an edge owing to their superior thermal path (heat pipe and copper block as opposed to brass tab and thermal epoxy).
Also interesting to note is that the XP-G outperforms 4-die emitters such as the MC-E up to roughly 1500 mA. Even at 2000 mA the XP-G managed 528.7 lumens, while a K bin MC-E I tested only managed slightly more, 538.5 lumens, at 500 mA per die. Granted, an M-bin MC-E would do somewhat better, but even there the difference wouldn't be huge.
Overall, the XP-G is another quantum leap in performance from Cree.
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Solo Rider
Newly Enlightened
- Joined
- Feb 22, 2009
- Messages
- 8
Jtr1962.
Yeah, good post, nice work, thanks.
:twothumbs
Solo.
Yeah, good post, nice work, thanks.
:twothumbs
Solo.
Try to drive LEDs with pwm the output will be lower but you can eliminate the thermal loss.
At 1% duty cycle the output will be 100 times lower @ low currents but WILL peak FAR farther.
And finally you will calculate the lumens without the thermal effect
At 1% duty cycle the output will be 100 times lower @ low currents but WILL peak FAR farther.
And finally you will calculate the lumens without the thermal effect
HarryN
Flashlight Enthusiast
Nice work as usual Joe. I would really like to see the comparable and more realistic 60 C results for an MC-E and the XP-G when you have a chance. Droop can be a big factor in LED applications, and it would be interesting to see if Cree has really worked its way past this.
Thanks
Harry
Thanks
Harry
ICUDoc
Enlightened
Wow that efficiency at 1000mA is amazing! Now to find the right reflector...
And thanks very much again!
And thanks very much again!
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blasterman
Flashlight Enthusiast
- Joined
- Jul 17, 2008
- Messages
- 1,802
Yeah...that's pretty startling. I'm hoping we see pure blue versions of these devils because they are likely to be a quantum leap over blue P4s, and we've already discussed a significant application for those. I'll let you know in a week or two how my initial experiment is going.
Otherwise, as somebody mentioned above, we need to hold some applause for the performance of these killer emitters and awknowledge that 6500k -vs- 4500k is like benchmarking dual core processors vs single core. Hyper efficient cool-white emitters is a given, but when you move to the neutral/warm-white phosphor category the efficiency hit is quite severe. This is really what I'm waiting to see with the XP-G.
Good testing regardless.
