1S Li-Ion charger IC with built in LDO

[osannolik]

Hi,

I'm looking for a charge + voltage regulator circuit that is capable of charging a 1-cell Lipo at at least 100-300 mA and can be operating with the battery disconnected as well. I really need this to yield a very small total PCB footprint, so I have been looking for charger IC's (SMD) with built in LDO's but only found LTC4063:

http://www.linear.com/product/LTC4063

Unfortunately, it appears that it can only provide a voltage output while the battery is connected. I want to be able to power my circuit using the source of charging while no battery is connected. I.e. the voltage regulator output should be 3.3 V if the battery is connected or at least if the charge power source is connected. Voltage regulator output does not need to provide more than 30-50 mA.

Any tip or suggestion is welcome!

[Canobi]

Have a look at the MCP73833. Failing that, if your talking about using it while plugged in, you could run the + - rails from the regulated output for the ic to a second terminal point to use when the battery is disconnected.

[osannolik]

Thanks for the suggestion. The problem with that circuit is, from what I can see, it does not have a built-in LDO with 3.3V output. Indeed I can supply the system without any battery, but if the battery is present, I still need an external LDO.

However I found this alternative that appears to solve my problem:

LTC3553
http://cds.linear.com/docs/en/datasheet/3553fc.pdf

3x3 mm QFN with charger, LDO and buck converter. Quite impressive.

[mikerj]

The STNS01 does pretty much everything you want, apart from having a 3.1v LDO which is a better fit to the characteristics of a lithium ion cell, and most micros etc. these days will happily run at 3.1v.

A 3.3v LDO will drop out of regulation before you've used the available energy in the cell.