TA - if you are interested in doing a small 15 mm driver, let me know. Here's what I had in mind for my ideal 15mm driver:
- make it FET+1 - probably can't afford space for a triple, even vertical space is usually very tight when I use these, in 14500/16340, and several small e-switch 18650 lights as well. Will probably use the thin board OSHPark option
- small LFPAK33 FET is fine - Richard and wight, others have recommendations - I got them as well
- eliminate the R1/R2 resistors - I'll work on the 1.1V ref version, as per DEL
- do the DEL design, partially at least - the 4.7 ohm is important to precede all circuitry, accept the LED+ of course
- need pads for pin#2 (OTC or switch), and also an external pad for pin #3 (just one - I can get grnd from lots of places)
- if can't fit full 85 layout, it's fine to go with bent pin method, just ensure clearance for programming clip
- according to DEL, should be ok to drop the C2 cap as long as we got the 4.7 ohm resistor in
- for the FET resistors - dunno if necessary. Probably need info from DEL. Might not be so necessary with the LFPAK33 FET, maybe? I would definitely use/try these without the FET resistors
The big difference from what we have on OSHPark and/or from Richard is the 4.7 ohm resistor, full pads for pin #2 and #3, plus the savings of space with eliminating R1 and R2. Whatever you can do to keep space on the grnd ring, or make it as wide as possible, or leave one edge of the board with free space, that would be great. Sometimes I have to file down one or 2 edges of the driver to fit it into a tilted position.
Like this: