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TAS5711 SS_Timer in BD mode

KANJI SHIBATANI
Mastermind 6205 points
Other Parts Discussed in Thread: TAS5711

 Hello

My customer is suffering in POP noise of TAS5711 in BD mode / BTL.

Also, they had found same POP noise in TAS5711 EVM.

When they had add 2.2nF to SSTIMER, even though BD mode,  phenomennon was fixed. ( Please see attached pdf file)

TAS5711 Data sheet p24 says SSTIMER cap should be removed ( left floating ) in case BD mode.

Is data sheet correct?

If yes, do you think add 2.2nF to SSTIMER  even BD mode?

Please give me your advise by day after tommorow..( sorry in hurry)

Best Regards

150225_TAS5711_pop_noise_investigation_EVK_n_PCB.pdf

 

 

 

 

  • 0
    TI__Guru 57800 points

    Hi Shibatani-san,

    There is no harm in adding a capacitor to the  SSTIMER pin in BD mode. 

    SSTIMER function is to give a softer transition after exiting shutdown, this is required when the device is configured in AD mode to avoid artifact issues. The soft start is not necessary in BD mode, but having SSTIMER capacitor helps avoiding  pop noise. Capacitor size determines the start-up ramp, 2200pF is the maximum recommended value.

    Datasheet suggestion to leave that pin floating has the only purpose to save bill of material cost when the device is configured in BD mode. 

    Best Regards,

      -Diego Meléndez López
       Audio Applications Engineer

  • 0 in reply to Diego Melendez
    Mastermind 6205 points
    Hello Diego-san,Thank you very much for your quick responce !Best Regards
  • 0 in reply to KANJI SHIBATANI
    Mastermind 6205 points
    Hello Diego-sanThank you for your support, and I am sorry to bother you again.
    Please adivse one more question from customer...Question
    In the TAS5711 data sheet, SSTIMER should be left floating in BD mode, but Please give us the reason why
    data sheet says so..
    Customer found the overshoot ( also POP) in the EVM also in case BD mode/ no caps.
    Do you think data sheet should be revised?
    "The SSTIMER pin should be left floating for BD modulation (BTL and PBTL modes) and in 2.1 mode."
    Customer hope your answer soon( within 2days)Best Regards