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TAS2505-Q1: TAS2505-Q1 mute release timing after DAC Channel power up

Takeshi Kasuya
Expert 3940 points
Part Number: TAS2505-Q1


Hi,

I have a couple of questions from customer.

Back ground of this questions.

Customer observed pop noise when DAC Channel power up.

Before DAC Channel power up, the following registers are set to unmute. 

Speaker Volume Control 1、Speaker Amplifier Volume Control 2、Speaker Amplifier Control 1

They changed sequence of those register settings and pop noise has gone.

1. How long does user need to wait to release mute after DAC Channel power up?

2. Is there required order of register settings like those register is set at last or any key care points?

Regards,

Kasuya

  • 0
    TI__Guru** 111175 points

    Hi Kasuya-san,

    It is recommended to power up and unmute the DAC at the end.
    In addition, the DAC gain adjustment can be made gradually by enabling soft-stepping, as described in Application Reference Guide section 2.4.2.2.

    Best regards,
    -Ivan Salazar
    Applications Engineer - Low Power Audio & Actuators

  • 0 in reply to Ivan Salazar
    TI__Expert 3940 points

    Hi,

    Thank you for the prompt response.

    As for Q1, you mean that wait time is zero after DAC channel is power up correct?

    Regards,

    Kasuya

  • 0 in reply to Takeshi Kasuya
    TI__Guru** 111175 points

    Kasuya-san,

    You can wait no time from DAC power up to release the DAC mute, however if there is pop at the output, you can enable the soft-stepping so that the DAC gain is adjusted gradually when it is unmuted.

    Best regards,
    -Ivan Salazar
    Applications Engineer - Low Power Audio & Actuators

  • 0 in reply to Ivan Salazar
    TI__Expert 3940 points

    Hi,

    Thank you for the prompt response.

    I got further questions from customer.

    1. Why you recommend DAC power up and unmute at last?

    Customer observed pop noise when unmute SPK AMP and SPK Vol then DAC power up.

    2. How long customer needs to wait below sequence?  between DAC power up and unmute  and SPK AMP power up, SPK Vol unmute

    DAC Power up and unmute -> (wait time) ->  SPK AMP Power up unmute, SPK Vol unmute

    Regards,

    Kasuya

  • 0 in reply to Takeshi Kasuya
    TI__Guru** 111175 points

    Kasuya-san,

    What is the sequence that customer follows (mentioned in your original post) that shows no pop during power up?
    This device documentation suggests to: power up DAC but keep it muted- -> power up SPK amp -> unmute SPK amp -> unmute DAC

    There is no wait time specified between DAC unmute and SPK amp power up, if you ask this for pop noise mitigation, then the sequence would be as pointed out above.

    Best regards,
    -Ivan Salazar
    Applications Engineer - Low Power Audio & Actuators

  • 0 in reply to Ivan Salazar
    TI__Expert 3940 points

    Hi,

    Thank you for the prompt response.

    They always observe pop noise.

    Let me confirm a couple things.

    What do you mean by device documentation? Application Reference Guide?

    Why you recommend unmute DAC at last?

    Regards,

    Kasuya

  • 0 in reply to Takeshi Kasuya
    TI__Guru** 111175 points

    Kasuya,

    From the original post: "They changed sequence of those register settings and pop noise has gone." that's why I thought that no-pop test was already accomplished.

    Yes, Application Reference Guide.

    If soft-stepping is enabled, it will be applied to the DAC gain, so if you unmute DAC at last, the soft stepping would help reducing pop.

    Best regards,
    -Ivan Salazar
    Applications Engineer - Low Power Audio & Actuators

  • 0 in reply to Ivan Salazar
    TI__Expert 3940 points

    Ivan-san,

    Thank you for the prompt response , however, customer wants to know the reasons why you recommended "unmute DAC" at last.

    power up DAC but keep it muted- -> power up SPK amp -> unmute SPK amp -> unmute DAC

    Please explain the reason why unmute DAC at last  (instead of unmute SPK at last).

    Regards,

    Kasuya

  • 0 in reply to Takeshi Kasuya
    TI__Guru** 111175 points

    Kasuya-san,

    As explained before, unmuting DAC at last would allow soft-stepping to reduce transients at the output:
    "If soft-stepping is enabled, it will be applied to the DAC gain, so if you unmute DAC at last, the soft stepping would help reducing pop."

    Best regards,
    -Ivan Salazar
    Applications Engineer - Low Power Audio & Actuators

  • 0 in reply to Ivan Salazar
    TI__Expert 3940 points

    Hi,

    Thank you for the response.

    Customer understood your point.

    They need to confirm a couple of things.

    Q1 : Is it possible to happen other issue except pop noise if applying DAC unmute just after DAC power up?

    Q2 : All the registers are set to "Reset value" after Software Reset Register (Page0, Address:0x01) is set to 0x01.

            Is this correct?

    Any other behavior will happen to do that?

    Regards,

    Kasuya

  • 0 in reply to Takeshi Kasuya
    TI__Guru** 111175 points

    Kasuya-san,

    Q1: No, device is operating fine if DAC is unmuted just after powering up

    Q2: Yes, the registers are reset after SW reset

    Best regards,
    -Ivan Salazar
    Applications Engineer - Low Power Audio & Actuators