Correct connection of RTC battery backup

I want to connect a battery for RTC backup to an EMX module. I have a few questions.

  1. Will the RTC_VBA pin still pull from the battery when the module is powered up? I.e. does this pin need connected to a 3.3 volt source when the system is powered up?

  2. Do I need some kind of resistor between the battery and RTC_VBA?

  3. Anyone have an example of circuitry for this or even recharging circuitry for a rechargeable coin battery?

Thanks in advance

See how it is connected here

To help you plan better, EMX has internally a diode from 3.3V to VBAT

Gus, in that schematic it uses a coin battery for backup.
Can a super cap be used instead? If so, can you recommend a size to use.

You can use super cap, the size is factor of how long you want it to run. We used 0.22F before IIRC

Thanks, I’ll do some experimenting.

Thanks! That helped.

Attached is what I ended up with if anyone else is looking.