Best way to power Arduino (Nano), and a 2A module

Hi everyone!

I’m currently working with a module that sometimes needs 2A (for a short amount of time), so I can’t use Arduino built in voltage regulator. I would like to ask you, which is the better (or is there any better) way to power Arduino Nano and the module in my circuit. (I’m using an L78S05CV voltage regulator)

Please check the attached image. Which one is better and why?
A) Powering the Nano from 9V through the built in voltage regulator (using VIN pin), and using external voltage regulator to power the 2A module.
B) Powering the Nano (using 5V pin) and the module too, through the voltage regulator powered by 9 volts.
(I know the best way would be to power the whole circuit with regulated 5V instead of 9V or else, but I want the power supply to be optional - like from 7V to 12V).

Also I would like to know that is it save to connect the Nano to PC with it’s USB, while the whole circuit is still powered by A or B method (removing power source while on USB is not an option, because the module needs the power)?

Thanks in advance!

circuit_a_b.png

I would use (A). That guarantees that Arduino is getting a good regulated 5v, no matter of the quality of the external regulator. It also allows for USB connection.

Thank you!
Just curious: Would (B) work with USB anyway?
(I don't want to try it out and kill my Nano, thats why I'm asking instead :slight_smile: )

Cant say.

frzsombor:
Thank you!
Just curious: Would (B) work with USB anyway?
(I don't want to try it out and kill my Nano, thats why I'm asking instead :slight_smile: )

B would work just as fine, the Nano has a series diode to prevent 'back flow' from 5V to USB 5 volt.