I love how they look.
Your dedication to details is crazy!
Ideas for some hardware mods,
If you increased the value of C4 (1nF) it would slow down the turn ON of Q1. Also if you added a cap in parallel to R4 on the input side you could add some delay. And a cap in parallel to R7 would slow down the turn ON. This is referenced from the schematic in your linked post.
For HDR FET, to quickly turn OFF Q2 you should add a resistor in parallel to C6 from the gate to source. Otherwise the gate charge has no path to bleed off.
Ah the linear driver. I think C4 should be kept as the minimum value that can prevent oscillations, any further slowing down would be undesirable, same for C3 that is dependent on the maximum current ripple deemed acceptable.
A resistor in parallel to C6 in order to quickly discharge it would need to be a very low value which will create a voltage divider, Q2 won’t be able to turn on.
Edit :
It discharges through the diode and then the MCU’s pin, with a resistor (R11) to limit the current.
Very cool. I hope it functions as intended. This is really approaching ultimate driver status.
What is the target host?
D4v2 (22mm)
Thanks 
While waiting for the new boards I measured the efficiency :
I haven’t forgotten this and will try to look into an Anduril patch soon. There’s just been a lot going on here.
Congrats! This certainly is remarkable, although the dip in efficiency at low input voltage and high current is too. Guess this in practice should be inconsequential. I'd love to see figures at 2.8V.
Now I really wonder how other same class drivers fare in this regard. 
No worries of course.
I’m quite satisfied with the numbers, one thing to note is that I measured this with a current clamp (UT210E) so it’s not super accurate. I do have precision shunts but I still haven’t made a board for them, I’ll need 4 voltmeters too…
At 3V the efficiency indeed decreases more, the input current is 12.65A at 5A out. The datasheet shows higher efficiency at 30W but in my case I have a reverse polarity protection PFET (5.2mΩ max at Vgs=–2.5V) costing ~2% and the 10mΩ current sense resistor costing a little less than 1%. I assume that in their test board they use large traces and maybe even larger copper weight, decreasing resistance and heating, they don’t say what inductor they use unfortunately.
I could gain maybe 1% by using a 1.8uH XAL7070 (4.5mΩ), for the flat version with the XAL7030 there should be a significant difference between 2.2 (15.1mΩ) and 1.5uH (8.4mΩ). I kept the 3rd output cap emplacement to help manage the higher ripple current with a lower inductance.
i saw a couple of diagrams in which they used a 1.5uH. Haven’t checked out their evaluation board yet, but that is a little hot-rod of a boost converter.
Yep they do use 1.5uH in the example circuits, I only had 2.2uH 7070 and 7030 in my inventory but I took a few 1.5uH 7030 with my last order.
Trying to adapt it to the FW1A/3A.
There are several issues with this light, firstly the shallow driver cavity which doesn’t allow the use of 3mm tall inductors, 2mm tall ones are too anemic to be used with say 3A@6V for a B35AM, or 2~3A@9V for a 3535 triple. I don’t exactly know how deep it is but if it’s more than 2.3~2.4mm then we could use a 0.8mm PCB with a spacer.
The second issue is the flawed stock design of the switch tube assembly, there should obviously be a spring somewhere to account for manufacturing tolerance, but in the case of the use of a handmade spacer it is even more important.
I found small spring loaded contacts that could potentially work :
They are 0.63-1.25mm tall giving sufficient play for the switch tube to make a good connection.
But that means that the switch tube has to be shortened by ~0.8mm, which I suppose should be doable with a file or sand paper, maybe by mounting it on a drill to turn it.
Anyway I don’t have any FWxA, I used webplotdigitiser to get dimensions from the lume1 PCB, but if anybody has one disassembled laying around I’d be thankful for precise measurements.
What’s so special about this host anyway apart of complicated design of back E-switch and tight driver space.
Well, as you said, the tail e-switch I suppose, though I’m not a fan of tail switches so you wont find me defending it.
looks similar to manker mc13
BLF Q8 have nice host for creativity and crying for better driver. If you are bored, you can try to design proper boost driver for 6v or 12v led config ;))
Do you know the dimensions ? I have an MF01, 4x18650 too :
Driver 48mm
Cavity ID 47mm (not counting the three mounting holes)
Cavity depth 11mm
Ideally it should be a relatively universal 4x18650, 3x21700 boost driver, capable of 1S and 2S input, with say… 2 phases, either 1 or 2 output channels.
Found some pic of Q8 insides
Plenty space for 10+mm coil.
Q8 driver diameter about 47.5mm
Here Texas Ace FET+1+N Q8 driver , but you can download source code and use only outlines and drill file ;))
That’s perfect, thanks.
Hi thefreeman. Very interesting progress over your designs. Also I am impressed from your skills in electronic design for that little time you are here in forum. It is interesting about that dual buck driver which you are designed. More interesting is how do you share the current between two DC/DC converters. Are they work in parallel or just that buck drivers are used in dual channel configuration for high dynamic range?
About current spike there is problem with opamp feedback. It is very slow to go in regulation for that little time. Solution is to be used better high speed OP. Some time ago as you I was interested to design some boost driver with MP3431 and TPS61088 and tried some PSpice simulation and that current spike is very obvious. See my post in thread about Convoy MP3431 driver.
I think we can share some ideas about improvement of that design.
About FW3A I have the measurement about tail PCB because some time ago I designed PCB for tail swich mod with better push button. Also I made the PCBs but the now because of shortage of components I can’t find buttons in stock now like many Attiny85 chips.