Sorry if this question is a bit broad, or too part-suggestiony. I've been trying to find a good solution for over a month (and three board revisions) now, and I hope someone has an idea I haven't thought of.
I've got a sort of UPS system, in which I need to charge (at ~1a) a 12v, ~50ah lead acid battery (which has a continuous load of about 0.15a). I have a 15v or 12v supply that I can tap off of, and I have a micro that's monitoring the battery voltage anyway, so I can output a charge termination signal. Pretty basic, right? I first tried an LM317 CC system, but that dissipated way, way too much heat. Also it caught fire. I then spent way too much time trying to find a switchmode battery IC, but I never found one that was:
- less than $20 all told
- Not huge (pcb footprint wise, I only have about 1 cm^2 of board space).
I then tried to use a standard switchmode regulator with an adjustable current limit (the LM3663), but that didn't work, and I haven't found any other switching ic that met my requirements.