I have been reading up on grounding and power tracking in PCB design, and want to put a few dumb questions that I'm not sure on yet...
My questions are in context of relatively low DC voltages/current on a 2-sided PCB (say, 15V@3A max), connected with an arduino to supplying it with voltage and break out pins to connectors, with no radio or high-speed comms.
If I have a circuit that includes a DC supply and a Battery (with IC-controlled charging and powerpath control), their 0V/Ground terminals should/must be connected, right? I've been confused by talk of 'isolation', which I assume refers to using mosfets, diodes, etc to ensure their positive voltages are isolated.
I've also seen reference to 'separate power supply returns' (i.e. 0V). In a low voltage/current circuit as referred to above, is this needed for on-board step-down regulators, battery ground, etc? Does it mean having a star topology to a common point, or is just having a ground plane on each layer of the PCB, with these connected at the nearest point OK?
While I get the basic concept of ground loops, I'm confused about it within a circuit. Taking an arduino shield as an example, if I connected the shield to more than one arduino ground pin, would that potentially cause a loop? Looking at the ethernet shield, it appears to do this.
Also, how 'bad' is it to use vias to join ground planes together? I'm trying to avoid this when routing, but have a busy PCB and it's doing my head in.
I've seen talk of it being desirable to avoid crossing signal and power tracks. Is this really going to matter in this context?
Is it advisable to add a small resistor on the 0V DC connections from battery and DC supplies? I saw this suggested to 'prevent ground current flow'.
Lastly, if using a metal enclosure, or a plastic case with a metal chassis, is it good/bad/indifferent to connect the PCB's ground to the chassis (in one place only)?
Thanks in advance...