[sdiy] Analog & Digital Ground

[harrybissell]

Hi Seb...

I would not put a bead in the ground line. You do not want inductance
there (imho). Better to just separate the ground traces so the PIC and
opto
current cannot cause voltage drops on the analog circuits.

The bead would be a good idea in the positive supplt, where it will
decouple
the two supplies.

H^) harry

Seb Francis wrote:
> 
> Hi,
> 
> I'm just laying out quite a large board which is almost all analog,
> except for a PIC&opto for the MIDI interface.
> 
> Normally I have totally separate analog and digital grounds which are
> joined right the way back at the PSU (at the end of the power lead), but
> in this case the PSU is on the same board.
> 
> I am thinking that I should separate the PIC&opto ground from everything
> else with a ferrite bead.  The power is already separate (it has its own
> 5V regulator).
> 
> Does this sound sensible?  Also, should I hook the 5V regulator to this
> digital ground as well?  And perhaps even connect the power input to the
> 5V regulator via another ferrite bead?
> 
> Thanks,
> Seb