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TPA3116 highly noise

Other Parts Discussed in Thread: TPA3116D2EVM

Hi,

I am testing with the BT+3116+speaker module. I do test successfully with the BT module I built together with the EVM board and speaker part. Now I am trying to apply that on my self-designed PCB board. The only thing I changed now are the values of the LC filter part(from 680nF and 10uH to 15uH and 470nF), others all following the typical application on the 3116 datasheet. I got much noise now, which can hardly hear the music. Why do this kind of thing happen? I have two guesses:

1. The change of LC filter value

2. I placed wrong layout of inductor on the PCB board, so I am now using the wires for the connection.

Can anyone help me understand why the and where the noise come from?

Attached is the layout image.

  • Can anyone help me with this? Thanks
  • Hi, Molly
    Which kind of noise? It is strange if you only change the LC filter value which you described in the thread. Could you use a oscilloscope to capture the noise?
    BTW, can you hear the noise if in idle state?
  • Hi Peter,

    looks like I fix the noise occasionally. Got another issue now, it was like that music sounds quite different when I use my own PCB board and the EVM board. Seems that the low frequency are filtered out. As I mentioned, the only thing I changed is about the LC filter part. So what do you think may cause this problem? Something wrong with my layout or LC filter value causes?

    Thanks
  • Hi, Molly
    If you only change the LC filter, it has no effect to low frequency. What is your low frequency mean? <1kHz or <20kHz?
  • I didn't check the specific value, just judge from the hearing now. Actually I don't know how to discribe this situation. For example, when I use the EVM board, music can be heard like in volumn 1, but now they can be heard around like 4 or 5. Also, if turn the volumn to maximun, when using EVM board, the music will sound quite loud, but now it's sounds like an old radio?! i don't know how to discribe that. When using the medium volumn, sounds good except it sounds like lower than usual. I tried my best to explain the situatuation. Please let me know if you want more information~
  • Hi, Molly
    1) check the input capacitor. It should be 1uF, you can find the capacitor in TPA3116D2EVM (C1/C2/C3/C4).
    2) check the bootstrap capacitor (Need be soldered normally), the value should be 0.22uF, you can find these capacitor in TPA3116D2EVM (C10/C12/C14/C16).
    Maybe you can send the schematic to us for a review.

    3)Check the PLIMIT pin voltage, it should be 7V if you did not change the voltage divider resistors. 

  • Here is the schematic, changed nothing except the LC filter part. For the voltage, will check tomorrow. You mentioned 7V, no matter what volatage I use to power it on, should all be 7V? I am using 12V now.

  • Hi, Molly
    I checked this schematic, it should be no problem. Try to check OUTPR/OUTNR/OUTPL/OUTNL with oscilloscope, make sure the PWM wave switching normally. Test on the left side of L7/L8/L9/L10.
  • Hi..
    Is the other side of C12 and C14 connected to GND? If not, then there will be no bass.
  • Molly, Did this work for you? Thanks, Jeff