5% chance of ending civilization isn't bad odds. At least nobody would be around to blame me.
Basically the same conclusion I can to, if I won’t be around to get yelled at, who cares?
I'd be inclined to advertise the merits of this thing a little more in the first post, or I could rephrase that and say to describe the functionality.
The PWMless adjustable current regulation does improve efficiency both in the LED's and even a little in the driver itself. It took a little thought to (hopefully) get right with an attiny controlling it, and it may even be a first in open-source drivers. It may be that the driver as a whole still isn't remarkable for other reasons, but that doesn't make implementation of these tricks any less meaningful.
Oh I did update the parts list by removing the bleeder and the jumper and giving pointers on good surface mount jumpers if anyone wants one.
If you want to put together a rundown you are welcome to and I will put it in the OP.
I simply didn’t have time or the brain power for my usual long description post in a thread that no one seems to read but us lol.
I had planned to come back to it later and add more details when things slow down a bit around here, I just wanted to get it active before I forgot about it.
Hey, I’m reading! I’d bet there are several others as well. We just don’t have anything intelligent to say, so we keep our keyboards silent! 
I think DB or someone was adamantly saying he would fork out $300 for a AMG version if it got him 2% more battery life. So I think there will be a tester soon. I'll almost surely test it eventually myself, just not before I get that Q8.
Anyway, yeah, ok I'll think about if I can make a few words about maybe the constant off-time IC and that. Part of my problem commenting on constant off time, is that while I know well how it works, I don't fully undertand why or even if all hysteretic bucks perform worse as far as ripple, so I'd have trouble making that as any kind of general comparisson. Fundamentally, hysteretic control doesn't seem to require more ripple. It does have different effects on frequency. Particular implementations of hysteretic control may require more ripple though, possibly even feasible implementations for some reason I'm missing.
If you give a basic rundown of the specs and capability (I honestly have forgot what all the final design specs worked out to lol, too many long days) I can touch it up to sound pretty.
DB fork out money for Mo POWAH, not battery runtime. I know how to change cells easy enough.
Been watching, reading, scratching my head a lot. (not sure if that last part is y’alls fault or my dogs)
So I want a tiny AAA sized light with a belt carry battery pack and this driver, external, all the light is for is to hold the emitter and the rest is copper. Should work fine. 
Yeah, if you're going to do that, you can pick up a cheap analog buck to put inline, and a pot to control it. This will just buy you one-hand button click operation.
By the way, I know you know lights. But anyway I'll point out probably the obvious that a tiny copper light isn't going to maintain as much power at a sustainably comfortable temperature as a larger aluminum light. Separting the batteries also means less case to spread heat over, but less weight to hold in hand too of course. For sustained power it's mostly about surface area, a bit about emmisivity, and only very little about conductivity of the case so long as it's pretty good. Of course for brief turbo modes in a tiny light, copper sounds like a good way to go. The volumetric heat capacity of copper is 22% about 38% higher than aluminum but you pay for that in weight a few times over. Its density is almost 3x higher but aluminum has a very high specific heat capacity. I'm pretty sure this matters much more than conductivity for short burst performance, once you get past the PCB at least.
I guess in the end it's not actually the high voltage that lets me get power out of pannies. Well yes and no. A given current through the leds requries the same current per cell however you stack them. But voltage sag doesn't limit the current draw this way, neither sag due to high current, nor "sag" of partially depleted batteries. It just lets you push them harder. That part is really true of a boost converter too I suppose.
Anyone try this yet? I've been absentee here on BLF for a while, but I'm leaving "work" behind over Christmas break and am catching up on some reading around here.
Not that I know of, I simply do not have the money to try it myself but would love to hear if someone else has given it a go!
What is the estimated cost per driver?
Excluding the PCB cost (which is about $1.50 each if you order from china, but you have to buy 10 of them) the parts look to be a bit under $20 from Arrow. Although the FET is not available from arrow and we never got around to finding one that was. From digikey it was like $23 total.
I was thinking could I have more than 1 of these buck converters going from the same MCU like an ATtiny84 which has more I/O pins available.
What do you think? Host and size would not be an issue for me.
I suppose you could but it would be one ugly setup, better to run either a custom made driver for the job or run multiples as they are IMO.
Plus running buck converters in parallel can be interesting, they generally do not share the load evenly and take up more space then simply making a larger buck to start with.
I see.
Well I wanted around 450W output from 12*18650 in a custom host. I have not seen a converter of that magnitude (450W output) that and that can also be PWM-ed with a
high frequency for a custom UI.
With that much power output I am afrid you are looking at 1 of 2 options.
A: Get a pre-made buck converter, there are lots on ebay and design your light to fit it. Then use a simply externally mounted pot (or possibly magnetic ring) to adjust brightness. This is simple, cheap and effective.
B: Go with a completely custom made buck driver that will cost a lot in time and cash just to get a UI.
With a light that powerful and large I am not sure that a UI would be much more useful then a simply pot knob? Not like you are just going to be tossing that in your back pocket! lol.