Battery Powered Application

[ElecKathy]

I am designing my first battery powered product. I am planning to use a Li-ion battery cell pack (10.8V, 4800maH eg.

http://www.batteryspace.com/index.asp?PageAction=VIEWPROD&ProdID=2211

). I want to design a built-in charger for the product, so that the user can simply plug in an AC/DC adapter to charge the batteries. My question is, when the adapter is plugged in, should the portable device run on the external power supply or the recharging batteries? (For example, when using a cell phone that is being recharged, is it running on the batteries or the external power supply?) Would I use FETs to do that? A block diagram would help.......
Oh also, do you know of any suitable battery charger ICs ?
Thanks!!!

 

[IRstuff]

http://para.maxim-ic.com/Default_BatteryChargers.htm

The choice of whether you can run your product while charging is completely up to you. BUT, it does mean that your charger will be LARGER, since you will need to run about 10 times higher power through the charger to charge the battery and provide operational power with no additional drawdown of the battery.

Many manufacturers will "cheat" and provide a charger that cannot power the product by itself. One of my cell phones is like that.

TTFN

 

[felixc]

Texas Instruments also has a line of battery charger IC, that they got from the Benchmarq company that they purchased some years ago. Benchmarq used to be a very good player in the battery charger and "gas gauge" ICs for battery applications.

You can find design and applications notes (and typical implementation schematics) at TIs site as well as in Maxim's.