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TLV320AIC3104: Question of Noise Problem with TLV320AIC3104 DAC to Line-Out Path

Part Number: TLV320AIC3104

Hi Sir,

Customer encounters a noise problem with TLV320AIC3104's DAC output (pin 27, pin 28) which needs product line's tips to identify the potential issue:

1. No noise problem with ADC to Line-Out path (confirmed by maximum setting on register 15, 19, 81. 86)
  - R19 (Page 0/Register 19: MIC1LP/LINE1LP to Left-ADC Control Register)
  - R15 (Page 0/Register 15: Left-ADC PGA Gain Control Register)
  - R81 (Page 0/Register 81: PGA_L to LEFT_LOP/M Volume Control Register)
  - R86 (Page 0/Register 86: LEFT_LOP/M Output Level Control Register)

2. No noise problem with grounded I2S DIN.
3. Noise was found on Line-Out when noise source (ex: hands) approaching I2S DIN. AIC3104 keeps sending noisy signals with noise source removed. Noise problem could be solved by toggle the register 37 off and on again.
  - R37 (Page 0/Register 37: DAC Power and Output Driver Control Register)

Pls let me know if product line needs more information for trouble shooting. I can send schematic by Email as needed.

Thank you and Best regards,

Wayne Chen
05/22/2018





  

    

  • hello Wayne,

    a schematic might be helpful.  Also I assume you've taken a look at the Application note "Common Noise issues in Audio Codecs"?

    best regards,

    -Steve Wilson

  • Thank you Wilson. We will submit schematic and clock, software configurations by Email...Wayne Chen

  • Hello Steve,

    With the schematic and I2C configurations we sent by Email. We confirmed the clock configurations:

    - MCLK – 12.288MHz -> MCLK/LRCK ratio=384 (12.288MHz / 32kHz = 384)
    - BCLK – 2.048MHz -> 64fs (2.048MHz/32kHz=64) -> 32bit audio for stereo
    - LRCK (WCLK) – 32kHz -> Sample rate = 32kHz

    We got clear picture to duplicate the noise problem:

    1. CPU to send noise-like I2S DIN to AIC3104 during power up.  AIC3104 sends noisy signal on LEFT_LOP (pin 27), LEFT_LOM (not used).

    - AIC3104 keeps sending noise on LEFT_LOP after CPU stops to sending DIN (or grounded DIN). Noise problem could be solved only by toggle the register 37 off and on again.

    CH1-DIN, CH2=LRCK

    Zoom-Out

    2. Grounded DIN during power up - No noise problem occurred.

    Would you pls provide tips to identify this noise problem?

    Thank you and Best regards,

    Wayne Chen
    05/24/2018

  • Wayne,

     

    This clock configuration does not align with their register configuration.   They are currently using the CLOCKDIV_OUT as their codec_clock.  But their Q value = 17 (see register 3)

    Codec_CLK = 256*Fsref => 256*48khz = 12.288Mhz

    So your Q value should be 2.   Refer to the clock diagram from datasheet:

     

    The Audio data format is also not currently set to 32bit.  Currently it is set to 16 bit.  (see register 9)

     

    Please have your customer make the following changes and let me know how it goes.

     

    Reg 3 – 0x 20

    Reg 9 – 0x 30

     

    Best regards,

    -Steve Wilson

  • Hi Steve,

    With the following programming sequence, we are not able to solve noise problem. Would you pls advise tips to check it up?

    1. Power Up
    2. Set AIC3104 Reg 3 = 0x20, Reg 9 = 0x30
    3. Turn ON audio jack channel ?

    Thanks a lot.

    Wayne Chen
    05/25/2018
  • Wayne,

    You sent a full register configuration to me via Email right? The registers I mentioned above are modifications to the register configuration that your customer is using.

    Your customer should modify their configuration so that register 3 and register 9 reflect the values I have provided.

    best regards,
    -Steve Wilson
  • Hello Steve,

    Yes, my customer has checked the application note (Common Noise issues in Audio Codecs) and updated the register 0x03 and 0x09 following your recommendations (Reg 3 = 0x20, Reg 9 = 0x30) while we are not able to solve noise problem from DAC.

    We assumed this is not an out band nose because there is no noise problem with I2S input grounded.

    Wayne Chen
    05/28/2018
  • Hi Steve,

    As mentioned in Wayne's reply, we follow your suggestion to change the register setting (Reg 3 = 0x20, Reg 9 = 0x30). We still can't solve noise problem from DAC. Could you share your experience with us to check this abnormal status?
  • Teresa,

    Can you show me a screen capture of the noise?

    best regards,
    -Steve Wilson
  • Hello Steve,

    I am updating customer's register setting. The data of offset N is the content of register N-1.

    i2cdump -f -y -r 0-255 0 0x18
    No size specified (using byte-data access)
    0 1 2 3 4 5 6 7 8 9 a b c d e f 0123456789abcdef
    00: 00 11 10 04 00 00 0a 00 00 00 01 00 00 00 20 20 .???..?...?...
    10: 0f ff fc 78 f8 fc 78 f8 86 00 fe 00 00 fe 00 00 ?.?x??x??.?..?..
    20: 00 00 00 cc c0 00 00 00 00 00 00 7f 00 2f 2f 00 ...??......?.//.
    30: 00 00 0f 00 2f af 00 00 00 0e 00 00 00 00 2f af ..?./?...?..../?
    40: 0f 00 00 00 00 2f af 0e 00 00 00 00 00 00 00 00 ?..../??........
    50: 2f 80 00 00 00 4b 00 00 00 00 2f af 03 de 0c 00 /?...K..../????.
    60: 00 00 00 00 01 02 00 00 00 00 00 00 00 00 00 00 ....??..........
    70: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
    80: 00 11 10 04 00 00 0a 00 00 00 01 00 00 00 20 20 .???..?...?...
    90: 0f ff fc 78 f8 fc 78 f8 86 00 fe 00 00 fe 00 00 ?.?x??x??.?..?..
    a0: 00 00 00 cc c0 00 00 00 00 00 00 7f 00 2f 2f 00 ...??......?.//.
    b0: 00 00 0f 00 2f af 00 00 00 0e 00 00 00 00 2f af ..?./?...?..../?
    c0: 0f 00 00 00 00 2f af 0e 00 00 00 00 00 00 00 00 ?..../??........
    d0: 2f 80 00 00 00 4b 00 00 00 00 2f af 03 de 0c 00 /?...K..../????.
    e0: 00 00 00 00 01 02 00 00 00 00 00 00 00 00 00 00 ....??..........
    f0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................

    Thank you and Best regards,

    Wayne Chen
    05/31/2018
  • Thank you Wayne,

    Can I see the Screen capture of the noise you are seeing?

    best regards,
    -Steve Wilson
  • Hi Wayne, 

    register 3 should be 0x10.  not 0x20

    best regards, 

    -Steve Wilson

  • Thank you for your advise. We will inform customer to update it and keep you updated of test result...Wayne Chen

  • Wayne,  

    This may simply be normal behavior.  Please take a look at the application report entitled "Out of Band Noise Measurement Issues for Audio Codecs"

    in particular you notice a dramatic increase in noise once you play audio.  This is discussed in the document,  see the FFT measurements below. 

    You can See that once music has been played there is an increase in out of Band noise.  For many applications this may not be an issue,  especially since the range of human hearing is 20hz-20khz,  but this noise can be filtered out,  and should be if the output of the codec is driving a Class-D amplifier.  

    Please take a look at this application report and let me know if this is indeed what you see.  The register configuration you provided looks good so I am assuming this is the issue. I appreciate your patience, It can be hard to diagnose "noise issues" without tangible data. 

    best regards, 

    -Steve Wilson

  • Thank you for your elaboration, Steve. ..Wayne Chen