I was about to put a battery charging circuit into my schematic, when I read up on my MCUs VBAT pin. Quoting from the Datasheet:
3.9.6 Battery Operation: "An internal VBAT battery charging circuit is embedded and can be activated when VDD is present"
How can a miniature MCU handle battery charging? Have I missunderstood what they're trying to say?
Also, there is a table (page 26) of which peripherals are available during VBAT operation, and almost all of them are unavailable, does this mean I should implement my own charging circuit and just disregard the VBAT pin altogether (connect it to VDD)?
There is just one feature that is worth connecting the battery to VBAT pin, but I don't know how it will work when powered from VDD...:
3.15.3 VBAT battery voltage monitoring*" This embedded hardware feature allows the application to measure the VBAT battery voltage"*