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TAS6754-Q1: Behavior During Power Fluctuations (Presence of Pop Noise, Necessity of Hard Mute)

Takayama Shunsuke
Prodigy 10 points
Part Number: TAS6754-Q1

Tool/software:

Hello,

We’re currently working on the design of a car audio system using the TAS6754. As we prepare for power fluctuation testing, we’d appreciate your insights on the following points:

  1. If both VBATT and PVDD suddenly drop to 0V, is pop noise likely to occur?
  2. If pop noise does occur, what kind of countermeasures are recommended?
    We’ve prepared a hard mute signal on Pin 22 (GPIO), using the output from a +B voltage sensing IC.
    Would this be effective in suppressing pop noise?

Thanks in advance for your support.

Shunsuke Takayama

  • 0
    TI__Mastermind 45085 points

    Hello,

    1. If you remove the VBAT or PVDD suddenly the device will see an undervoltage event and place the output into a Hi-Z state, set the appropriate UV fault bit, and pulll the /FAULT pin low.  The device will not guarantee a pop free output when it has a fault event.
    2. If you can mute the device faster than the VBAT and PVDD collapse, you can control the output.

    Regards,
    Gregg Scott

  • 0 in reply to Gregg Scott
    Prodigy 10 points

    Thank you for your response, Gregg.
    I have a follow-up question.
    Could you please tell me the detailed time it takes for a fault event to occur after VBATT or PVDD is removed?
    Also, could you tell me the detailed time it takes for mute to be activated after Pin 22 goes low?

    Regards,

    Shunsuke Takayama

  • 0 in reply to Takayama Shunsuke
    TI__Mastermind 45085 points

    Takayama-san,

    The decay of the VBAT and PVDD depends on the system design.  The UV will trigger when the voltage on the capacitance attached to these pins decays enough to trigger the UV.  This time is undetermined by our device, but is a system decay.  

    The Mute function uses the digital volume control to ramp down the output level. The ramp speed is determined by the volume ramp speeds and the volume setting at the time of the initiation of mute.

    We do not guarantee a pop free shutdown if VBAT and PVDD are removed without the proper use of MUTE and STANDBY pin usage.

    Regards,
    Gregg Scott

  • 0 in reply to Gregg Scott
    Prodigy 10 points

    Thank you very much for your detailed response.
    Your explanation as well as the mute and standby functions, was very helpful and informative.

    Regards,
    Shunsuke Takayama