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Original question:

TAS5805M: TAS5805M delay time for input to output with FIR filter

TAS5805M: TAS5805M Latency

Ryoji Itoh
Prodigy 710 points
Part Number: TAS5805M
Other Parts Discussed in Thread: TAS5805,

Hello

 Here is additional question from my customer.

1.  Latency time is 126us when input sample rate is 96KHz.  it time was mentioned at https://e2e.ti.com/support/audio/f/6/t/822365

     It time is between pre SRC and post Crossber?     if no, Please let me know start point and end point for this time.

2. Latency time is not constant. it is depend on DSP processing.  What parameter is dominant time of processing for latency perspective when FS=96KHz and FS=48KHz?   Customer is evaluating by using pure-path console.  Customer is expecting to get answer by pure path console parameters.

Regards, 

  • 0
    TI__Expert 6295 points

    hello, Ryoji,

      we use oscilloscope to measure latency. Accounting timing from SDIN first rising edge to output first Vpeak high. see attached picture.

      to get stable TAS5805 latency, you can do below register config when device enter PLAY mode.

           w 58 00 00

           w 58 7f 8c

           w 58 00 23

           w 58 3c 60 3f 01 c0

    regards

    Linda

  • 0
    TI__Expert 6295 points

    hello, Ryoji,

      we use oscilloscope to measure latency. Accounting timing from SDIN first rising edge to output first Vpeak high. see attached picture.

      to get stable TAS5805 latency, you can do below register config when device enter PLAY mode.

           w 58 00 00

           w 58 7f 8c

           w 58 00 23

           w 58 3c 60 3f 01 c0

    regards

    Linda

  • 0 in reply to Xiaolin Qin
    TI__Prodigy 710 points

    Hi Linda,

     Thank you for the update.

    1.  Latency time is 126us when input sample rate is 96KHz.  it time was mentioned at https://e2e.ti.com/support/audio/f/6/t/822365

         It time is between pre SRC and post Crossber?     if no, Please let me know start point and end point for this time.

    ->  Measurement data mentioned that "DIN to Analog out" time is around 201us.  
         Above answer is "DIN to Analog out"   Is it correct?

    2. Latency time is not constant. it is depend on DSP processing.  What parameter is dominant time of processing for latency perspective when FS=96KHz and FS=48KHz?   Customer is evaluating by using pure-path console.  Customer is expecting to get answer by pure path console parameters.

    -> My customer is trying to estimate latency. and they wants to know what parameter is dominant time in the DSP process.  Please explain the customer's questions.

    Regards,

  • 0 in reply to Ryoji Itoh
    TI__Expert 6720 points

    Hi Ryoji,

    1. Our clarified latency is the Digital input to Analog output, so it's the whole signal path latency.

    2. Except for default DSP processing configuration, latency is highly related to signal frequency and DSP processing. Most the latency happens with biquads filter, and the Group Delay curve as below.

    Regarding the Signal Propagation Time vs Group delay, you can refer to this article: 

    Regards,

    Matthew

  • 0 in reply to Matthew Miao
    TI__Prodigy 710 points

    Hi Matthew,

     Thank you for your support.
    Additional question is below.

    1. Totally 15 bi-quads filter are available with TAS5805M.  If customer add 1 ~15 filters in series.  Latency will be increased?   Is it correct?

    2. My customer wants to try to make same measurement environment on the following picture. 

       Whare is measurement point for Ch1 Analog output?      (ex after LC filter or Differential probe was used. )  

    Reagrds,

    Ryoji

  • 0 in reply to Ryoji Itoh
    TI__Expert 6720 points

    Hi Ryoji,

    1. PPC3 will show all enabled biaquads group delay. So the latency of different frequency signal can be caculated through final group delay curve.

    2. The output waveform is the math of (OUTPUT+ post LC) - (OUTPUT- post LC).

    Regards,
    Matthew

  • 0 in reply to Matthew Miao
    TI__Prodigy 710 points

    Thank you Matthew.

    Regards,

    Ryoji