On Sat, Oct 9, 2010 at 3:14 AM, RussellMc wrote: > That sounds like a job for either a single AA (14500 size) =A0LiIon or a > prismatic (rectangular) of similar volume. > USB charging of a single LiIon cell or of up to 3 NimH in series is "easy= ". I can't believe 20 days have passed since you wrote this reply. Yikes! I have been poking away at this project, albeit much slower than I'd like. I found a place to purchase both 14500 and 18650 cells, and I've ordered a couple of each, with protection circuits on the cell to avoid problems. I'm leaning towards the 14500 due to size at the moment, but we'll see what I end up with. I'm worried that with the much greater capacity of the 18650 the charging times will become unwieldy. Which brings me to what I'm still after, a charging solution. I had a look at the Linear site, and they have a chip that seems interesting, the LTC3558. It's a combined charging circuit plus it includes a voltage regulator. Nice, but not entirely what I'm looking for in that I can't really handle a QFN package at the moment. Then I looked at the Microchip MCP73811 and MCP73812. They are nice and tiny, but I'm a little unsure how I'd handle the various options that are present in my device. So here's what I'm looking for. I will be using a single cell, either 900mAH or 2600mAH. The unit will be running self powered, off the pack, connected via Bluetooth, or it will be connected to the computer via USB. If it's connected via USB to a computer, it would be nice if it could be doing some charging. In addition, to minimize the number of connectors, it would be nice to use the USB jack as a source for charging from a higher current wall adapter. If the charger doesn't provide it, I'll need a 3.3V regulator (I have that lined up already). I would like to be able to use the device even if it's connected to an external power source, so I can use those "backup" USB power sources if I find I'm running low on power. Ideal package would be surface mount, but something I could hand solder, QFP, SO, SOT, etc. Non exposed packages (like DFN) are probably a bit too hard for me at the moment. I'm currently making my way through the manufacturer's sites, but I'm somewhat confused about the chips that would allow me to do the things I'd like to do. Any help would be appreciated! Josh --=20 A common mistake that people make when trying to design something completely foolproof is to underestimate the ingenuity of complete fools. =A0 =A0 =A0 =A0 -Douglas Adams --=20 http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .