Has anyone received their boards yet? Anyone built one yet? I've built several of these now in different configurations and have them in different lights, and I feel very confident that they work and work well.
A few more thoughts and tips:
1. Absolutely do not try to solder this by hand. You need to reflow to get these done right, especially since the thermal pad under the buck IC is critical to proper performance.
2. Make sure you get enough solder underneath the Buck IC's thermal pad. The thermal vias tend to wick up some of the solder, so you need a bit more than you would think.
3. Space your low and critical levels a bit farther apart than you normally would. For example, if you normally use 160 and 145 for your low and critical values, use 170 and 145 instead. The way that the buck driver loads the batteries is different than with a DD or linear driver single-cell setup, because the current draw actually increases on each cell as they drain instead of decreasing, so having values that are too close together leads to an immediate shutoff after the LVP is activated with no or very little "in between" time.
OshPark expects my boards to be back around 4-19. The OP was 4-5 and I ordered 4-7. That being said I don’t even have all the stuff to attempt this build yet, nor am I confident enough that I won’t screw it up.
Oh… I just assumed. I don’t plan on making enough of these to make a larger order from mouser worth it. How many parts will be shared between this one and the 20mm?
Preliminarily it is all the same except for the flyback diode and sense resistor, although maybe I’ll end up with two different 20mm boards so that those who have parts for the 17mm and don’t need more than 3.5A-4A can use the same parts.
I probably won't be offering them complete for a while because I just don't have time to build them right now. I have built a few for a customer who asked about them a few months ago, but besides that I've only built them for myself.
That said, I have two of them complete right now that I've built that are just sitting on the shelf I could sell. I will list them on the garage sale page.
Richard, do you already have enough spares for a parts kit now or would you have to order? Reason I ask is I already have a order with you that I’m sure you haven’t had time to complete. If you already have the stuff then I’d like to purchase a couple kits and have it shipped with the other order. If you would have to order it, I’d probably just place another order with mouser. I can always find more stuff to buy I don’t really need, just like shipping with you! I have a 2S UF-1405 that I had planned on putting an E2 Torch in and using a low current buck, but I’d rather push a G2 at 4a.
The Mouser parts list is putting me off a little. DigiKey I've found cheaper in the past when comparing qty 1 or 10 for example, so I've only ordered parts from DigiKey up til now. Also trying to figure qty of boards to make in this size, what lights best fit, etc. I'd probably want to use it in 1 or 2 e-switch lights, or lights with a wider driver, so, bigger board options (and higher power) of your next generation may be better for me, or take the chance with a contact board setup which you are not recommending. Dunno yet.
I shop at Mouser based on price, and price alone. For me Mouser has almost always been cheaper than Digikey.
For e-switch, you've either got to be OK with some quiescent current drain, or go to a bigger driver layout with more parts.
Hold out a little longer for the bigger boards. You have to think of the thermal path of one of these like you do with a high-powered LED---it will fry itself if pushed hard without a sufficient thermal path. We are pushing it already by making everything so small.
Hhmm - I gotta re-check part prices again then. Maybe I was just spot checking the MCU's, FET's, diodes - Hhmm: I see the ATTiny13A's are definitely cheaper at Mouser....
Yep, can't think of much I can do with a buck driver at 17mm. I have no P60 tube extensions, but think I got 1 or 2 for Convoy C8's, and pretty much all my 2S cell lights use a bigger driver. The limited 18350 capacity can't justify converting a 1 cell 18650 light over. Also 4A is very limited if driving 2S cell triple LED lights, and converting the 3 LED's to parallel - obviously 2S cells driving 3S LED's won't work with a buck driver - boost is needed.
One group that may be very interested in this driver is laser enthusiasts. Especially, if it provides pretty clean power. Most laser diodes need much less then 4amps of power and some have fairly high Vf's. They are always in search of a good boost and buck drivers. If you don't belong to Laser Pointer Forums, there are some senior LPF members here on BLF. Maybe one of them can help introduce you there to get you some street cred.
I've looked at a few drivers over there before. I think they'll be surprised to see that none of the IC markings have been sanded off and the files and information are available for free.
What does "HP" stand for? High Performance. I've got one running at 5.5A in a UF-1405 right now and it seems to be holding up well so far. I ran it on 100% for 7 minutes straight and it didn't burn up, so I think there's a good chance that it will hold up in the long run. That light finally runs like it should have from the beginning. A bit more testing is needed, but I think that is the direction I'm going now. The same design will be able to be used from 1A all the way up to 5.5A in 17mm by just changing a few components on the board.
Also, I was able to build and test a 20mm. It will be available soon. That one can also do 5.5A (or maybe even more...haven't tried it yet. The only place I'd want more would be in powering a triple or MT-G2. For an XM-L2 5.5A is sufficient).
I've got one running at 5.5A in a UF-1405 right now and it seems to be holding up well so far. I ran it on 100% for 7 minutes straight and it didn't burn up, so I think there's a good chance that it will hold up in the long run. That light finally runs like it should have from the beginning. A bit more testing is needed, but I think that is the direction I'm going now. The same design will be able to be used from 1A all the way up to 5.5A in 17mm by just changing a few components on the board. 
Good job 