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TVP5158 Grounding scheme

Roma Bhagat1
Prodigy 110 points

Other Parts Discussed in Thread: TVP5158

Hello,

We are desigining a video board wherein we are using multiple TVP5158 to cater to multi-channel video input.

We have a query pertaining to AGND (VSsA analog ground) and GND (VSS, Digital ground).

Query is:
1) Should each and every IC have VSSA1 below the device or should all IC's have a common VSSA connected.
2) If each and every IC should have independent VSSA moat(copper cutput) , then where exactly should this be shorted to DGND.

Pls do revert on above at the earliest.

Thanks,
Roma

  • 0
    TI__Mastermind 43875 points

    Roma,

    Unfortunately this is not a trivial question and is very much dependent on your specific board layout.

    Fundamentally what you need to do is ensure that the digital switching current loops do not cross or merge with the analog current loops.

    If you ensure good placement allowing the currents in the ground to not intersect or otherwise interfere then you can often get away with a single common ground plane for everything.

    In some situations this is difficult but you can sometimes use slots to control the loop currents.

    Try to analyze where the loops are and check if they potentially overlap. Gaps or cuts in the planes will cause the return currents to go around cuts. Traces over cuts is very bad. Don't do it. If there is a cut then make sure that the traces also go around the cut.

    BR,

    Steve