About PMIC feedback line artwork

[111kmw]

Hi,

I have question about PMIC feedback line. (Specially NXP PMIC, FS84 and PF7100)

When we design the PCB, feedback signal is routed using line generally .

How about plane?

For example, there is power plane inner layer, and we connect power plane and feedback pin using via.

Is it ok? or Is it not good? (Because of high current...?)

Please give a answer.

Thanks,

[guoweisun]

Run feedback traces of the regulators in the inner layers to keep them shielded from
the power and noise nodes.

[111kmw]

hi, guoweisun

Thanks for your reply.

Your answer means "Don't connect diretly power plane and feedback pin using via."

Is it right?

Thanks,

[guoweisun]

Correct!

[111kmw]

Thanks, guoweisun!

Could you explain why feedback line should be shielded from the power? (not Switching node)

Because power plane's current can be changed?

Please give me answer!

Thanks,

[guoweisun]

The power path combine with more noise including high frequency/low frequency which will affect with  FB signal.