I'm looking to power a small hand-held personal project from two sources. Either a USB input, or a pair of AA batteries in series. I need a regulated 3.3v output, and (possibly) a 2nd 1.2v output.
I've been trying to find a suitable IC for this, preferably something I can source from LCSC because I plan to use the JLCPCB/SMT service, or at least something that could be handsoldered (and I'm not that great at soldering).
Here's the problem. I would love to support any AA sized battery, from NiMH all the way up to lithium ion 14500s (not true AAs, but rather 3.7V Li in an AA sized package), but this means I would need a buck/boost that supports a voltage range from 1.8v (low end of NiMH) to just under 9v (fully charged 14500 Li). I couldn't find a single one that even supports that with a single input, let alone dual usb/bat inputs.
If I can't support any AA, then at least I would like to support the lithium ion 14500s (ie. 9v top end). I don't really need charging capability, but I would like support for dual input with some sort of smart switching between bat/usb, and proper USB current limiting. A power-good pin or similar would also be really useful.
Any ideas? I've spent nearly 5 days and looked over 100s of datasheets from TI, Analog, and Maxim, and have come up with nothing that fits the bill. This seems like a fairly mundane set of requirements... and yet I've come up short every time.
Any thoughts or ideas?