Teensy Audio Board VAG decoupling capacitor

E

eterelle

New member
Hi Everyone,

i currently have a project using the sgtl5000 codec in combination with teensy 4.1's to send audio over UDP. As the codec is the same as on the teensy audio board, i've been using it to prototype and also used part of it's schematic. My board however, has a bit of a noise problem, which is caused by the decoupling capacitor i used on the VAG pin. Replacing it with the one used on the teensy audio board solves the issue.
It would be amazing, if someone could give me a part number for that cap (the 0.15uF one connected to the VAG pin), as i'm not sure what to look for / what property of the capacitor is actually causing the noise.

Thanks in Advance :)
 
What kind of capacitor did you use that caused the problem? Its the most crucial component on the board as it decouples the analog reference so should be low ESR, low ESL, and not microphonic, I reckon.
 
MarkT said:
What kind of capacitor did you use that caused the problem? Its the most crucial component on the board as it decouples the analog reference so should be low ESR, low ESL, and not microphonic, I reckon.
Click to expand...
I was a little bit naive and thought it wouldn't matter THAT much... i had a bunch of 100pF capacitors on the board already, so i just used that. (I tried soldering a second one in parallel, which didn't change anything, so it's not the capacitance difference that is causing the issue).
This is the one i used: https://jlcpcb.com/partdetail/15530-CL10C101JB8NNNC/C14858
I'm replacing the capacitors by hand, so they can be smaller than 0603 (which i guess is better for lower noise?) as long as they're not too small to solder by hand.
 
I'm having pretty much the same issues of noise with the SGTL5000, didn't tried to change the VAG cap for C0G yet but there's any other recommendations to keep it as low as possible? can be good information for anyone that wants to integrate the codec to a custom board. Is it completely necessary to get split grounds?. For information I'm using a 2 layer board.
 
toyosm said:
I'm having pretty much the same issues of noise with the SGTL5000, didn't tried to change the VAG cap for C0G yet but there's any other recommendations to keep it as low as possible? can be good information for anyone that wants to integrate the codec to a custom board. Is it completely necessary to get split grounds?. For information I'm using a 2 layer board.
Click to expand...
The capacitor that's causing the noise for me is a C0G Cap... From my research, that's the best class to use for audio applications as it isn't microphonic..
 
MarkT said:
Yes that should work - but high value C0G caps are large, are you sure its 150nF?
Click to expand...
You were right, it's not... Somehow i managed to mix up 150nF and 150pF part numbers, and didn't catch it after countless times of checking the datasheets... a bit embarrasing, but at least my problem is solved :) Thanks everyone!
 
You must log in or register to reply here.
Back
Top