Power Domain - Suggestions

Hi, a newbie here. I am starting to create more complex designs in KiCad.

I am making an add-on card for STM32 Nucleo board. I figured it would be a good idea to have an extra regulator on the add-on card in case Nucleo cannot provide sufficient power.

In my add-on card, I will be getting one power supply from the Nucleo’s out, and then my own regulator setup. Now I have two options for designing the power distribution -

  1. Provide a jumper to choose between the active power source - either the supply from Nucleo or the additional regulator (connected to battery with charger IC). This way only one of the power source will be used within the addon card.
  2. Connect the second power source from regulator in parallel with the output from Nucleo board. This way I can choose to connect the battery in case I feel more power is needed.

I think the second one is a better choice. But either way, are there any special considerations while designing them ?

If I choose the first method, how do I implement power domain isolation? Should I create new power symbols like 3.3v_A, 3.3v_B etc or does there exist some smarted way to deal with it ?

Are those LDOs?
If so, you might want to read a bit here:

and here:

as this is far from simple.


Thank you very much Joan, that was quite informative!