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First the Osram Oslon Black Flat. I bought it from Mouser, the partnr. is LUW HWQP-8M7N. It only comes in cool white. Despite the many emitter tests that I do, I'm often guessing what generation a led is and how long it has been on the market, manufacturer websites are usually unclear about this, and sometimes someone more knowledgable than me has to correct me. In this case I think that this the second generation of Oslon Black Flat, and it came on the market not long ago in 2015.
This led is interesting because it has a small 1x1mm die (like the XP-E2), it does not have a dome, and the thermal resistance looked very promising: 4.3 K/W, which is very good for such a small die and way better than the XP-E2 Torch which is the led with the highest surface brightness that I had tested sofar (9K/W for the XP-E2 Torch) (edit:I was wrong here, after a suggestion by chouster, a quick calculation learned that an S4 XP-G2 reaches a higher surface brightness when at max).
Some initial observations. The Oslon footprint is a bit smaller than the XP-leds, but can be reflowed on XP-type boards, but not too much solder paste must be used because the led does not seat itself and excess solder can not be pushed out from underneath the led.
(Oslon left, XP-led right)
The die size is equal to the Cree XP-E2:
The light comes very cleanly from just the die, around the die it is totally dark (die at 0.5mA):
A very annoying feature of Oslon Black emitters is that the led-minus is electrically connected to the central thermal pad. This requires, when the led is mounted on a DTP-board, that the ledboard is electrically insulated from the flashlight body.
The test was done like all my more recent emitter tests. I described it in detail in my XP-L test. In summary: 1) just one led was tested, reflowed on a DTP copper board (XP-Noctigon 16mm) 2) I used my larger version II integrating sphere with much higher quality luxmeter, but that should not matter for results, 3) the output numbers and voltages were measured with the led close to 'steady state' for each current, so warmed up and settled, you should be able to get these numbers in a well heatsinked flashlight. Mind that these are output numbers of the bare led, in a flashlight there will be losses from light obstructions, lens and optic, 4) output is in 'djozz-lumen' defined as 1/550 of the output of my Sunwayman D40A on high setting, which I hope is close to the real lumen, but at least is consistent over all my emitter tests done in integrating spheres.
Here's the results, presented in a graph. I plotted the led together with my test results of a dedomed XP-E2 Torch U5 bin, that test was done earlier:
Now that looks well! The output of the Oslon Black Flat up to 2A is almost the same as the 'Torch', and above 2A it leaves the Torch behind, maxing out at 4.5A, compared to 2.8A for the Torch, the brightness at max is 50% more than the Torch. It looks like there is a new surface brightness leader among my tested leds (edit: also higher than a S4 XP-G2)! Because the maximum output is obtained at over 4V, the led can be run direct drive on a single Li-ion cell.
Much encouraged by these results, I did a Brinyte B158 mod with this (very) led and a direct drive AK-47A+FET driver (ledboard glued to the pill with an as thin as I could make it layer of Arctic Alumina Adhesive to get the required electrical insulation between led-minus and pill) in the hope that it would crush the throw of the dedomed XP-G2 S4 2B led, but unfortunately it did not, I got 'only' 285kcd from the Oslon BLack Flat, with 322kcd for the S4 2B. I'm not sure why it does not get that high, the amps were good (3.65A), perhaps these small dies are not imaged well enough by larger aspheric lenses to get the spot brightness of a good XP-G2.
Time will tell what this led will do in practice for thrower flashlights.
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Next in line: An Osram Oslon SSL-80 4000K 92CRI typ. of the latest available generation, partnr. GW CS8PM1.CM-KSKU-A535-1 . I bought it from RS-online. The rs-online webpage does not list the CRI, but the datasheet does.
SSL-80 leds are special in their emission angle: 80 degrees to half intensity compared to 120 degrees for almost all other leds. This is optically achieved by using a very high and sharply curved dome and a small die, I still have to check the die size by shaving a dome off, but I expect a 1x1mm die, like the Black Flat Oslon and XP-E2. The small emission angle gives much lower light loss if used in an aspheric flashlight, and a very nice defined hotspot in reflector lights. The small die however implies that it is not a high current high output emitter, the OslonSquare/XP-G2/Nichia119/219 have a more than twice as large die, let alone the XM-L2/XP-L die size.
The led is interesting compared to one generation earlier because according to the datasheet, the thermal resistance is lower, 5.3 K/W compared to 7 K/W for the earlier generation. Not a great difference but it should be noticable I guess. Further, the Vf is 0.2V lower, considerable. The package of the latest generation looks very much like the generation before but can be visibly distinguished by the way the phosfor is deposited, it looks like it is 'poored' after the die is assembled on the base, covering part of the base too, while the older SSL80 (the last led in the first picture) has the phosfor neatly confined to the die area.
At some point I guess also the 96CRI version will be available, in the meantime this 92CRI one is pretty nice too.
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Last led is an Osram Oslon SSL-80 4500K 96CRI typ. of one generation earlier, LCW CR7P.CC-KSKU-5J7K-1 , also bought from RS-online.
It is 96CRI 4500K, so almost directly comparable to an earlier version of 96CRI 4000K that I tested before a few years ago. Unfortunately the test method was different at the time, no integrating sphere measurements but ceiling bounce measurements with a reflector on top of the led. So the output numbers are not directly comparable. It is the led on the right in the picture at the top of this post.
I have put the test results of these two emiiters in the same graph, together with two recent but earlier tested high CRI leds: a gen.2 Oslon Square 4000K 92CRI typ. (there's a gen.3 already, want to test that too but I have to order through work and can do only so many orders for private use), and the Nichia 219B V1 4000K 92CRI.
*although the older gen. 96CRI SSL-80 test from two years ago can not be compared because of the different test method, with some 'educated mind extrapolation' it is clear that the output went up, and the voltage went down since.
*As you can see the two SSL-80 leds have not the high current and output capability of the Oslon Square or even the Nichia 219B V1, also the Vf is higher, although the newest generation comes close to those up to 2A, both in output and voltage.
*I would use these leds at 2A, at 80-90% of the maximum output, the output at that current is in the same ballpark as the bigger die leds and you have the benefit of the small beam angle in particular builds.
*the newest genaration has indeed a 0.2V lower voltage, great for use with smaller batteries and longer regulation. My first build with it will be a small 14500 zoomie :-)
Conclusion. These two high CRI SSL-80 leds perform clearly better than the previous generation high CRI SSL-80 that I tested two years ago. I think these leds are great for many high CRI flashlights, I really like the 80deg beam angle for several types of flashlights. A very important test has not been done yet: the judgement of tint and colour reproduction. I'm sure both will be fine, but because I can not measure tint and CRI quantitatively, it will be a subjective test when I have build the leds into a flashlight. I will update in this thread with that impression.
Thanks for reading!