Re: gEDA-user: pcb, howto partition power planes?

[DJ Delorie <dj@xxxxxxxxxxx>]

> Your board looks decent.  What kind of voltage resolution are you
> looking for (e.g., what IC are Uxx0)?

Those are the ADE7753 chips.  In theory, they're accurate enough to
meet all the IEC standards for power metering, but in my case, I only
need to know where all my kWh are going so I know where to start
conserving electricity for best gains.

> The first thing that leaps out at me is the large loop for power
> supply filtering on those chips (both AGND to AVdd, and DGND to
> DVdd).

The alternative was to put the bypass caps on the back, and I was
trying to avoid that (it makes assembly a little harder).

> Oh, and do you really want REF filtered to digital ground?

Er, no, that's a mistake.  I've noticed that before but keep
forgetting to fix it.

> One major trouble with split ground planes is when tracks cross
> the split, and the return path becomes high inductance.  Your board
> doesn't suffer too badly from that disease.  Most cases that look
> like that are actually differential signals, where the plane is
> not part of the circuit.

The chip is laid out with the analog pins on one side, and the digital
ones on the other side, so for the most part the signals stay over
their own planes anyway.


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