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Tlv320aic3106

James Del Signore
Prodigy 210 points
Other Parts Discussed in Thread: TPA2012D2, TLV320AIC3106, TLV320AIC3104

We presently have design which uses a  TLV320AIC3106 Codec  that drives a TPA2012d2 audio amplifier in a single ended AC capacitor coupled  fashion via its HPLCOM outputs. The TLV320AIC3106 Codec is utilized by a second party SOMM which we purchase as our  core controller. We have an issue that when the Codec finishes playing an audio stream and goes idle , there is a timeout period after which  white and shot noise is presented to the audio amp and is amplified loud enough to annoy the listener. 

I have rechecked the layout, decoupling caps, etc, for the TPA2012D2D2, and can't identify any noise sources.                                                                                         When I disconnect the TLV320AIC3106 Codec from the amp  by removing the SOMM,  the noise goes away. Touching QFN pins 19 and 23 on the  TLV320AIC3106 Codec intensifies the noise.

I can only conclude  that  it appears the TLV320AIC3106  floats its HPLCOM  outputs to the audio amp  after playing causing the noise.

There is a myriad of registers in the TLV320AIC3106 Codec which provides  many possible setup and operational configurations.

Has anyone  crossed this issue before, and determined how to correct it?

Jim @ Transact Technologies, Ithaca NY

  • 0
    TI__Guru* 84915 points
    Hi, James,

    I will take a look of this issue and I will answer you as soon as possible.

    Best regards,
    Luis Fernando Rodríguez S.
  • 0 in reply to Luis Fernando Rodriguez S.
    TI__Guru* 84915 points
    Hi, James,

    I apologize for the late response.

    I suspect that the noise issue could be related with the signal path. Could you provide your TLV320AIC3104 register configuration? Additionally, could you provide a schematic if possible?

    Thank you.

    Best regards,
    Luis Fernando Rodríguez S.
  • 0 in reply to Luis Fernando Rodriguez S.
    Prodigy 210 points

    I can't provide the register configuration, its buried in the Android  OS drivers of Variscite SOMM we are using. We have someone working on this.

    I hear you on the signal paths and am working on this , trying to tye Audio ground closer to our logic ground. while keeping the signal return paths over the source signals to the audio amp. We have done some simple changes to correct this by jumping isolation ferrites keeping a contiguous ground plane under the source signal paths. That said, the behavior we are experiencing doesn't   point at signal paths.

    1) At power up there appears excessive noise, but after playing a music file the noise goes away, then after a timeout period it comes back.

    2) We have some top level tools that can configure TLV320AIC3104  to single ended capacitve coupled instead of differential  ,however this has no affect.

    3) 1K pull downs of the HPLOUT and HPROUT  signals best mitigates the issue.

    4)  I am unable to upload a pdf schematic to you  using this post.

  • 0 in reply to James Del Signore
    TI__Guru* 84915 points

    Hi, James,

    The noise causes at the TLV320AIC3104 HPLOUT/HPROUT are often related with the register configuration. When the DAC is routed directly to the HP outputs, the output signal use to have more noise. So, we always suggest to route the DAC to the output mixers (red path).

    Additionally, another possible cause could be the out-of-band noise. In order to get a good measurement, it is necessary to add an external filter as the following document mentions: http://www.ti.com/lit/an/slaa313/slaa313.pdf.

    Please, take a look of this document and let me know if you have questions or comments.

    Best regards,
    Luis Fernando Rodríguez S.

  • 0 in reply to James Del Signore
    Prodigy 210 points
    Thank you, I apologize for not being able to provide more detailed information.
    We will forward this to our software group and attempt to get at the register configs to change this ...........Jim