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how it response with receivce I2S data -1 (0xFF) of audio AMP

Darren Lin71
Prodigy 30 points
Other Parts Discussed in Thread: TAS5731M, PCM5100A

Hi,

     Could you check how I2S AMP responses when receive data -1 (0xFF)?

     Because I have an I2S source when it is silcence, it will send out data -1 (0xFF),so I need to check the AMP response.  Is it also be sicence( it mentions at this moment the output noise should be the minimum)? Or there is other action from AMP output.

     Thanks       

  • 0
    TI__Guru 57800 points

    Hi, Darren,

    Welcome to E2E, Thanks for your interest in our products!.

    Could you please provide the part number of the amplifier you are using?. About your question, sending a value of 0xFF by I²S would mean a -1 (of ±32768) deviation from the 0x00 value that in general is the Digital reference as "mute". This value might be interpreted as mute on the amplifier, depending on the filter and processing.

    Best Regards,

      -Diego Meléndez López
       Audio Applications Engineer

  • 0 in reply to Diego Melendez
    Prodigy 30 points

    Hi Diego,

                 Thanks for your reply.

                 Curently we have two use case, one is DSP I2S out + TAS5731M.  The other is DSP I2S out + PCM5100A + Analogue AMP.  

                 So it means even those two chips are all support I2S data up to 32bits and my I2S only send out 0xFF(16bits). Than the two chips can define it as a " mute" signal?  is it correct?

                

               

                Thanks

  • 0 in reply to Diego Melendez
    Prodigy 30 points
    Hi Diego,

    Thanks for your reply.

    Curently we have two use case, one is DSP I2S out + TAS5731M. The other is DSP I2S out + PCM5100A + Analogue AMP.

    So it means even those two chips are all support I2S data up to 32bits and my I2S only send out 0xFF(16bits). Than the two chips can define it as a " mute" signal? is it correct?

    Ans we checked the SNR after the PCM5100A out, that only 95dB. Is the value expected?


    thanks
  • 0 in reply to Darren Lin71
    TI__Guru 57800 points

    Hi, Darren,

    Sorry for the delay. Both devices supports 16-bit operation, so if the I²S source only sends 16 bits of data I would recommend to configure the TAS5731M in 16-bit operation. The 0xFF data will be interpreted as mute.

    About the SNR, please make sure that your test is complying with the test conditions mentioned in the datasheet.

    Best Regards,

      -Diego Meléndez López
       Audio Applications Engineer