How do i choose a IC Battery Charger ?

You mean like one of these ?

Please note that Li-ion batteries are very delicate, and the charger must be sophisticated enough to handle the constant current and constant voltage phases of the charging cycle precisely. Hope that helps.

"very" and "precisely" overstate the problem. A better word would be "reliably". Charger ICs are quite common and cheap. There is little reason to roll your own and more than a million reasons[*] not to.

Google for MCP73831.

Caution it's a very small package 2x3mm QFN or SOT-23-5.

An application is here:

I have many of these boards in my projects.

hamilton

He said 3.6v, which probably means LiFePO4. I just got some MCP73123 for that purpose, and made an Eagle footprint to allow hand-soldering. Will let you know how I go.

Will you share your Eagle footprint ?

Sure - but I don't have it in a separate library. Try editing the following XML text into your of your LBR files.

The footprint has an elongated via as well as the heatpad, so I could locate a drill hole to help solder it from the rear. I wanted to make the hole bigger without making the pad bigger, but Eagle says naaah. You can drop the extra via.

Clifford Heath

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MCP73123

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Thank you all

this work for us

Except that it's nearly twice the price, almost no-one has stock, and you have to program your 3.6V termination with external resisters instead of getting it free. Oh, and it doesn't do the three-stage charging that's needed to get best results from a Li cell. Not a good alternative, I don't think.