we are currently developing a new custom carrier board for our devices. During the protoype phase we tested the Apalis iMX8QM using the Toradex Ixora Carrier Board V1.2A and all was good.
Now the first prints of our custom carrier boards have arrived and we noticed that capacitors on the Apalis iMX8QM 4GB IT are emitting sound/noise in a high frequency when assembled with our custom carrier board. The frequency is rather high ( > 14 kHz, 56 dB) and only a few of my co workers can even hear it. Because of this I am not sure if this even is an issue. Just to be sure we do not have any issues in the new design, I would like to ask you if you think this indicates a problem? If so, do you have an idea on how to detect it?
Thank you for your quick reply! I had a look at your Layout Design Guide with my colleague from Electronics and we have capacitors (100nF) on our carrier board. Further reading and looking at the Ixora Layout we determined that we need to upgrade the bypass capacitors to a multiple of 10uF. Since this will take some time I cannot yet tell, but we are pretty confident that this will resolve it.
I had this problem on the custom carrier board before. Sometimes the traces to the capacitors are too long and the circuit starts oscillating. I like to see you schematic and also the layout and component placement. You can send those to firstname.lastname@example.org.