Solving EMI problem at audio lineout on Rev. C1 boards

Discussion of your EDM baseboard, your add-on boards or other peripherals for your wandboard.

Solving EMI problem at audio lineout on Rev. C1 boards

Postby mjm987 » Sat Nov 22, 2014 9:56 am

When connecting/disconnecting an audio sink on the audio lineout connector on a running Rev. C1 board, sometimes the SGTL5000 will hang. From this state a power cycle of the board is needed.

On the old Rev. A0 board this problem did not exist.

Consulting the board shematics as well as the SGTL5000 datasheet I saw that both board designs the old Rev. A0 boards as well as the Rev. C1 didn't connect the HP_VGND as proposed in the datasheet.

The correct solution is to connect a 100nF ceramic capacitor on position R411 (from SGTP5000 HP_VGND to AGNDM).
(R411 is not connected at the Rev. C1 board but 0 Ohm at Rev A0. Both is wrong!)

Since then I had no more problems :-)

Matthias
mjm987
 
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Re: Solving EMI problem at audio lineout on Rev. C1 boards

Postby Tapani » Mon Nov 24, 2014 6:33 am

Thank you,

I've forwarded your post to the hardware team.
Tapani
 
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