why microchip removed GND details?

[hsn93]

hello, im looking into ATSAM4E mcu uController

why would they remove the details of which pin is which GND? did they connect them all internally and it doesnt matter anymore ?


it may sound silly question, but for me i think it would make some sense

[Daixiwen]

Maybe not internally but they probably required all those pins externally directly connected to the GND plane anyway. Separate ground islands just create problems.

[exe]

I'd ask them .

Here is what analog says: http://www.analog.com/en/analog-dialogue/articles/staying-well-grounded.html (see Separate Analog and Digital Grounds). They say different ground pin names doesn't mean they should be connected to different grounds. At least for their ADC they say all grounds should be connected together.

[Rerouter]

Having clues to what grounds to keep quiet, and how you should structure your least impedance loops is important, however I suspect this was to reduce people trying to split ground planes under a BGA,

to make very clear, for 99% of circuits, splitting ground planes will generally hurt you more than help you.

High edge rate signals have a return current that mostly follow the path of least impedance, In general, directly under the signal trace, and it wants to stay as close to it as possible. when you break its ground plane it will detour to get back to it, but if you just provide it a way to stay near that signal, e.g. jumping the ground over the split, next to the signal, it behaves mostly as if there is no split.

So for the most part, if you don't mess up the return path for the signals ground currents too badly, they are well behaved. So all that is left is keeping proper separation from analog / sensitive nets, you don't have cross talk issues if your traces are not near to one another.

If you have a big DC current that flows across the board, through your analog section and you want to separate it, this is one of the few cases where creating a local ground net can benefit, but in most cases I would probably just confine those high currents to there own traces, rather than causing chaos across the plane. Technically splitting the ground, but on the problematic net rather than the victim node.

[hsn93]

Having clues to what grounds to keep quiet, and how you should structure your least impedance loops is important, however I suspect this was to reduce people trying to split ground planes under a BGA,

to make very clear, for 99% of circuits, splitting ground planes will generally hurt you more than help you.

High edge rate signals have a return current that mostly follow the path of least impedance, In general, directly under the signal trace, and it wants to stay as close to it as possible. when you break its ground plane it will detour to get back to it, but if you just provide it a way to stay near that signal, e.g. jumping the ground over the split, next to the signal, it behaves mostly as if there is no split.

So for the most part, if you don't mess up the return path for the signals ground currents too badly, they are well behaved. So all that is left is keeping proper separation from analog / sensitive nets, you don't have cross talk issues if your traces are not near to one another.

If you have a big DC current that flows across the board, through your analog section and you want to separate it, this is one of the few cases where creating a local ground net can benefit, but in most cases I would probably just confine those high currents to there own traces, rather than causing chaos across the plane. Technically splitting the ground, but on the problematic net rather than the victim node.

so on that case, you would contact them to find the pin that is related to GNDANA ?

[Rerouter]

Ping them an email, and they should be able to send yo an older revision of the datasheet,