Does anybody have any ideas of a good IC that has dual cell Lithium charging but also automatically provides battery power or DC dependin on whats conected. i.e. if DC power is connected it charges the battery and supplies the device with power from teh DC socket, but if DC is disconnected it supplies the device with batter power, kind of like a UPS system but for LiPo cells (2 in series)??
Thanks
Craig
try to find max 1555 family IC…maybe
For the switch, use 2 diodes in an or-gate configuration. Google it.
I was looking at the BQ241xx family of switchmode charger chips from TI. They take up to 20V input and can charge 1 or 2 cells in series. I ended up going with the ADP2291 linear charger chip instead, since I was charging from USB and didn’t need the efficiency of the switchmode chip.
As Gussy states, you can just use a couple of schottky diodes with their cathodes connected together. When the external supply is connected, it will supply the current (since it is a higher voltage than the battery).
If your circuit can’t tolerate the voltage drop of the schottky, I suggest just powering the circuit from the battery. When the external power is connected, the battery charger chip will supply the current anyway.