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Power line noise

Max Zhegulin
Intellectual 420 points
Other Parts Discussed in Thread: TLV320AIC3204, INA219, TMS320C5515

Hi all,

 

In the attached file print screen from oscilloscope where captured output(yellow) and input (green) tlv320aic3204 signals. 

Source of the signal is Aglent waveform generator. 

I don't perform any signal processing, just record and play back.

As we could see at the output, around 50mV of noise was applied to signal.

 

What could be the root of this noise? 

I assume that it could be power line noise.  

Could I improve it by any INA219 settings?

Or 50mV noise is the best what I could get on this board?

 

Thanks!

 

Max

  • 0
    TI__Genius 14965 points

    Hi,

    It's too little information to suggest anything.

    1. What hardware platform are you using? 

    2. What software are you running?

    3. INA219 is power monitoring chip. I dont' think it can help anything.

    4. What is power source from?

    Regards,

    Hyun

  • 0 in reply to Hyun Kim
    Intellectual 420 points

    Hi Hyun,

     

    1. My hardware platform is TMS320C5515 EVM from Spectrum Digital. 

    2. Software is simple and based on test projects from CCS4 emulation/boards/evm5515_1 examples. 

    3. Ok I understood.

    4. Power source is power supply for this board from Spectrum Digital kit.

     

    I have some updates around this case.

     

    I made two measurements of codec output signal before and after codec initialization.

    In the first case output signal is fine, there were no noise components. 

    But in the second case I saw high frequency noise around Niquest frequency.  And this noise component  always exists on the codec output. 

    I suppose problem is near aic3204 settings.   

     

    Dear Hyun, 

    I understand that you can only advise, but not solve my problem, but any help will be appreciated. 

    What codec settings are influence on the output noise?

    Thanks!
    Max

  • 0 in reply to Max Zhegulin
    Intellectual 970 points

    Hi Max,

    I also get this problem on my C5515 EZdsp board running a simple audio loopback software. The output noise when using USB power supply (from desktop's USB port) is about 15-20 dB higher than when using battery power supply. Even with battery, the noise level seems to be too large too me (about -55 dB full-scale), so I think 32-bit support for this codec is nonsense.

    Probably I will redo the test with an output load to minimize EM interference through output analog parts.