I understand that ferrite beads can be used to reduce noise from a power supply input to an IC.
I understand that one selects ferrite beads based on its resistance at the noise frequency one wishes to reduce and I need to select the ferrite based on what frequencies I expect digital switching noise.
My question is: how do I know how large the impedance of the ferrite bead needs to be in the resistive region @ my target freq? This is the part it seems that every guide I can find on the subject excludes.
Does it not really matter precisely as long as the bead has a maximum current rating 50% higher than the expect operating current?