Yes it's possible and with a lot lower power, can definitely be made smaller too. However it's unlikely I'll have the time to work on it but I'm sure there are lots of other who will be :)
I don’t recall any in the 17mm size beside the KD BD8P. Which is both out of stock and unprogrammable.
Also, a small boost driver would allow to build a high-CRI EDC light using XHP LEDs.
I do have a 17mm version planned for the future, but not quite now yet!
Thank you for bringing this little experiment of yours to BLF.
I am also one that is very interested in trying one, whether building it myself with your flashed MCU or a complete driver.
Might would have to build a whole new flashlight from scratch just to honor your work on this ! 
Great work!
The idea of a boost driver for the XHP LEDs has been floating around this forum for how long now?
Someone finally has a grasp of how to get it done! 2017 is looking like a good year, in more ways than one.
Would love to put this driver into a nice host, maybe Texas Lumen’s upcoming c8-sized host?
How sweet would it be if cree decided to offer the xhp70.2 with a 3 volt option? All 4 dies would be parallel.
Just dreaming out loud. Lol
I can envision this is a smallish light with a beautifully tinted MT-G2, sure would love to see it…
I would love to try one of these out as well. I am thinking 18650 powered mini C8 with an XHP50.2. After having build one XHP50.2 in 4000k for an old SupFire I have, I have really decided that I like this new led. I would be willing to build 1 to test if I had a programmed MCU and a shopping cart list.
Looks like good work to me!
great job
i am interested too
Building this on 17mm size would probably need a sandwitch of 2 PCBs to fit all components
On the other hand you could try to bore the C8 to 20mm and use a spacer to the shelf, no retaining ring just the driver between spacer and tube
Is that something you would sell or is it for personal use only?
Realy like the output of my ee x7 xhp50.2
But the driver is….not great.
Would love to put one in a m2 or similar host.
Thanks for your kind words! I’m currently working on a write-up on this project and releasing all open-source as well as offering the boards on oshpark so everyone can build one for themselves. I do have extra boards and I can offer firmware-flashed boards with MCU at a later time, but I really will not have time to offer built drivers. I do understand it’s a bit tricky to put together and I highly recommend either a micro-soldering station with magnification for hand-assembly, or even better if you have solder paste (can apply using a needle) and reflow with an oven or hot-air. Updates will be on this thread.
I’m not quite sure if it makes sense from an electrical point of view, since there’s really not much use case for it except in flashlights (which makes up a very small % of their sales), and that it’s not electrically efficient since resistive losses go up by the square of the current.
I’m 100% sure I can fit it all onto a 17mm driver with no less functionality and with a single PCB. Just need to find some time to do it!
It takes a while to assemble this together by hand only because it’s fairly small. So I don’t really have any plans to offer these for sale as whole drivers, unless I have some help in getting this mass-produced! Otherwise I’ll be releasing more open-source so anyone can buy the PCBs themselves on OSHpark or similar and assemble it 
I'm seconding Dale's post, wow!
Very much interested in building a couple of these. Also very interested in the "New 0.4mm pitch micro programming header for ATtiny84A" you mentioned, and how to utilize it. I would like to be able to make "tweaks". I'm sure real estate is tight, but if you haven't yet, if you can add 1 to 3 pads for spare I/O pins, much appreciated. Indicator LED's is one thing I'm thinking of or possible dual e-switch support.
I'd also love to see those pics of the board blown up a bit.
What Dale and Tom said. Wow. Thanks for sharing the project with us and who knows, maybe I’ll build one that works.
Totalt understand that.
To me it would probably be morr of a pain to find all the correct components than the accual soldering.
I think if the 17mm works it would be a huge demand as there is nothing like it and lots of people want to get away from a 2×18350 setup.
I managed to get all the components on a 17mm board, I used a different digital potentiometer, so I had to change the connections to the ATTiny.
One more thing: In this design you need one wire across the board on the top side, so it’s usable, but not great…
Much more work needed for this design…
Would anyone buy these over the H1-A which is also 20mm?
If you could get a better firmware for your driver (with off time memory, etc…) then that would surely give it an advantage.
Squeezing it down to 17mm would be another big advantage for those that already use hosts with that size.
Otherwise, new builds can be done with hosts that take 20mm drivers.
Could you eliminate the air wire by using four-layer boards and running traces in the middle layers?
Sure that’s possible with blind vias and buried vias, but I’m stuck with 2-Layer designs on my software.
I think it’s even possible with 2-Layer and without an air wire, but that takes a lot of time, just positioning all the components.
Does Oshpark even do 4-layer? I think you’d need a larger minimum order from Seeed studio or someone else to get them. This is where I was thinking some of the miller’s donation/developement money should go if we want a boost design to get from open source to production.