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TLV320AIC10: Seperate planes or a single plane.

Michael Rourke
Intellectual 350 points
Part Number: TLV320AIC10

Tool/software:

I'm hoping to get some clarification regarding grounding the analog and digital sections of the CODEC.

We currently have three TLV320AIC10CPFB in a chain. All the analog signals are on one side of the CODEC, while all the digital lines are on the other side. In no instance do digital lines cross the analog lines.

At one time, the thought was to pull the analog plane and digital plane back to one point and connect them. However, more modern theory says to connect them to a solid plane and stitch as much as possible.

On our PCB, we have tied both analog and digital to a single plane and stitched as much as possible. (There is a ground plane on both sides of the signals.)

Half the boards are absolutely quiet when listening to the speaker out. The other half has a very, very slight hissing coming from the speaker. Since all the boards were built at the same time, they all have the same components.

I am interested to hear any thoughts TI experts might have to say about this.

Thank you.

  • 0
    TI__Mastermind 46625 points

    Hi Michael,

    Are the speakers the same or physically different between boards? If you move a "quiet" speaker to a "noisy" board does the issue follow the board or the speaker? You could do the same experiment with the codec itself to see if the noise follows the device or the PCB.

    Also can you measure any electrical difference in the output signal or the power supplies? Audible differences are a little hard to track down without numbers behind them.

    I don't disagree with your thoughts on the PCB grounding. If grounding was an issue I would expect it to happen on most if not all the boards, not just half of them.

    Thanks,
    Jeff McPherson