Analog versus digital GND pins

Hardware questions and issues with the FV-1

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muragavino
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Analog versus digital GND pins

Post by muragavino »

Hi there,

i´d like to use separate GND-planes for digital and analog ground (The two groundplanes connect only in 1 point.)
Which GND-pins of the FV1 are connected to analog circuitry and which to digital?

The FV1 will be on the same board with an ARM Cortex M4 with inbuild PLL. In a former post, there has been mentioned that SOCs with own PLL might create problems with the PLL of the FV1 when too close together. What can be done in regard?

Thanks in advance for every answer,:D
Michael
frank
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Re: Analog versus digital GND pins

Post by frank »

muragavino wrote: i´d like to use separate GND-planes for digital and analog ground (The two groundplanes connect only in 1 point.)
Which GND-pins of the FV1 are connected to analog circuitry and which to digital?
I believe all the grounds are tied together internally. Just the power rails were independent.
muragavino wrote: The FV1 will be on the same board with an ARM Cortex M4 with inbuild PLL. In a former post, there has been mentioned that SOCs with own PLL might create problems with the PLL of the FV1 when too close together. What can be done in regard?
Anytime you have multiple PLLs on the same PCB you risk them affecting each other. Keep them as far apart as possible, good by-pass caps close to the chips, just use best practices for layout and most times all is fine.
Frank Thomson
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muragavino
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Joined: Tue Apr 16, 2013 10:07 am
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Post by muragavino »

Thanks for the fast reply!

I will have to check if the GND-pins are connected in the FV1. If so, i could use the FV1 as GND connecting point.

For the PLLs, there is nothing else to do then to put the chips as far as possible and hope...

Thanks again!
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