PSU input section caps

Hi guys,

Since muffwiggler is down, I’ll post my question here. I’m designing a range of modules and wondering about the values of the electrolytic caps that are typically used in the power input section of a module (close to the ribbon connector). Normally all PSU lines are stabilized with something like a 47u, but I’ve also seen 22u, or even 10u being used. I assume this value is dependent on current consumption of the module, but I have hard time figure out which values would suite my new modules best. Is there a rule of thumb, best practice or formula I can use?

Best,

Rutger

As big as will fit the footprint?

You can model it with one of the various tools available such as Spice.

Thanks! I was hoping for a bit more of a structural / analytic answer though…