TPA3116 highly noise

Molly Wang

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.

over 8 years ago

0 Molly Wang over 8 years ago

Intellectual 390 points

Can anyone help me with this? Thanks

0 Peter Cao over 8 years ago in reply to Molly Wang

TI__Expert 5000 points

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?

0 Molly Wang over 8 years ago in reply to Peter Cao

Intellectual 390 points

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

0 Peter Cao over 8 years ago in reply to Molly Wang

TI__Expert 5000 points

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?

0 Molly Wang over 8 years ago in reply to Peter Cao

Intellectual 390 points

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~

0 Peter Cao over 8 years ago in reply to Molly Wang

TI__Expert 5000 points

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.

0 Molly Wang over 8 years ago in reply to Peter Cao

Intellectual 390 points

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.

0 Peter Cao over 8 years ago in reply to Molly Wang

TI__Expert 5000 points

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.

0 CWilson over 7 years ago in reply to Peter Cao

Expert 1920 points

Hi..
Is the other side of C12 and C14 connected to GND? If not, then there will be no bass.

0 Jeff Kohnle over 7 years ago in reply to Peter Cao

TI__Expert 6985 points

Molly, Did this work for you? Thanks, Jeff

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TPA3116 highly noise