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TAS5766 delay

Eric Raquette
Prodigy 250 points
Other Parts Discussed in Thread: PCM5142, TAS5766M, TAS5754M

We want to use this for active damping and I seleceted this chip to have the possibility to offload some filtering and protection from our MCU.

Now my colleagues are worried that the processing delay may be too much. We dont find any info about this in the datasheet.

So what is the minimum and maximum delay from the I2S input to the output? And how much is added for each biquad etc we use?

We input 16bit data at 48kHz with a 24.576MHz master clock. I set the switching to 16x48kHz and gain 14dB.

  • 0
    TI__Mastermind 46195 points

    Hi Eric,

    The delay from DIN pin to output is around 470us for Smart Amp mode or Bypass default mode at 48ksps. The delay of any biquad in the path depends on the filter properties which results in non-linear phase response (i.e. delay is a function of frequency). The group delay of the interpolation filter is 20/Fs. Some of the delay (e.g. 21us at 48ksps) is due to the time it takes to receive the serial sample that is being sent.

    Note that you can send the processed output directly to DOUT pin as explained in this wiki page: e2e.ti.com/.../3035.tas5766m-configuring-sdout-functionality

    Regards,

    J-

  • 0 in reply to J-
    Prodigy 250 points

    Hi

    PCM5142 (also has a miniDSP) can set the interpolation filter to:
    Filter Characteristics–1: Normal (8x) Delay time 20tS
    Filter Characteristics–2: Low Latency (8x) Delay time 3.5tS
    Filter Characteristics–3: Asymmetric FIR (8x) Delay time 1.2tS
    Filter Characteristics–4: High-Attenuation (8x) Delay time 33.7tS
    Table 19 in the datasheet shows the ROM program number for these to set in register 43.
    Can the TAS5766 not be set to low latency modes, register 43 says they are reserved?
    If this is not possible I will probably be forced to change to another amplifier.

    As a backup plan I have the possibility to input analog audio (via capacitors) to the INNx INPx pins, is this possible?
    Does the miniDSP have to be configured and have valid clocks for this to work (so that the amp is not muted/shutdown)?

    Eric

  • 0 in reply to Eric Raquette
    TI__Mastermind 46195 points
    The Smart Amp code is loaded into RAM using programmable mode and it uses the Normal 8x interpolation filter, so it can't be changed.

    An invalid or non-present I2S turns off the power amp portion. I need to double check, but I believe you can manually control it on P1_R6.

    If you do not need the Smart Amp processing, perhaps TAS5754M may be a better option. It is pin compatible with TAS5766M and it supports those low latency filters you mentioned.

    Regards,
    J-
  • 0 in reply to J-
    Prodigy 250 points

    Ok, thank you.

    With TAS5754M  can I use biquad filters when running DSP program 2, 4 or 7?

    Do I understand correct that if I use Purepath console to configure it will create a user program that is put in RAM and will use the standard interpolation filter?

    Or is it that only if a HybridFlow is used?

    Regards Eric

  • 0 in reply to Eric Raquette
    TI__Mastermind 46195 points
    Hi Eric,
    Biquad filters are only available in program 5, but that one uses an the interpolation filter in program 1 which is probably too much delay.
    Hybrid Flows is a User Program, correct, but not sure about the actual interplation filters that were implemented for those. I am copying people to this thread that are more familiar with the HybridFlow processing.
    Regards,J-