rechargeable battery backup circuit

[HasHx]

Hi

Can someone help me with finding the suitable IC for a rechargeable battery backup circuit, I have a 2.8 - 3.7 Li-po, 300-500mA battery. i want to put it on a circuit in a way to charge when its connected to the 3.3v source and run the circuit when disconnected...

Any ideas??

Thanks in advance.

 

[d123]

Hi,

LT4079 (2.7 - 60V, 250mA Linear Charger) or similar may be in line with requirements. Probably helpful to roughly know battery discharge during 3.3V disconnect. I've never used one, had it in mind for a solar charger. At least worth looking at how it functions and/or flow diagram in datasheet and seeing if there are similar but better fit if not the right thing for your circuit.

 

[dick_freebird]

A diode-blocked charging circuit is one piece, the
other is between the battery and load (there, a LDO
which can give you 3.3V from max cell to discharged-
somewhat voltages (the "somewhat" goes to how
much uptime - a buck/boost DC-DC could maximize
this). 3.3/3.7V is 89% efficiency so maybe not a lot
of incentive to go with the switcher approach.