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TAS5707: pop noise and SSTIMER reg

KesTam
Genius 9550 points
Part Number: TAS5707
Other Parts Discussed in Thread: TAS5733

Hello Audio Folks, my customer is using TAS5707. They have found a pop noise in playing a sound and stop it. They say it is OK after removing the added EQ and change the SSTIMER reg 0x1A from the default 0x0F to 0x08.

My understanding on the SSTIMER should only relate to PWM starting/stopping. If TAS5707 is already running with PWM output, the SSTIMER should be nothing related to the operation.

So, my first guess is that the device goes to protection for some reason. They may be a PWM stop and restart so that the SSTIMER will affect the pop. I have then asked customer to monitor the PWM output to see any PWM stop and restart. But, customer says that they don't see any PWM stop and restart. Then, I don't understand.

My question is why SSTIMER will affect the device in normal operation.

Regards,

Kes

  • 0
    TI__Mastermind 25845 points
    Hi KesTam,

    Shawn will be taking a look at this and should be getting back to you after the weekend. In the meantime, having a scope shot of the PWM switching during audio turn off could be helpful for troubleshooting this pop noise issue. You are right that this should only matter in a shut down/start up or change in the PDN state.

    Best,

    Alex
  • 0
    TI__Mastermind 24835 points

    Hi Kes,
    According to datasheet, 0x1A register is used to control the soft-start and soft-stop period following an enter/exit all channel shut down command or change in the PDN state. We don't know whether it also works in normal operation. I did an experiment on TAS5707 EVM board, measure the output when writing 0xFF(0x20 previously) to 0x7 register(volumn register). The scope captured screen is as below. The result is the same for the different 0x21 register settings.

    So I don't think this register also works for normal operation. And I don't know why customer saw this. As you know this is a very old device, so I'm afraid we can get very limit support from design team.

    Best regards,

    Shawn Zheng

  • 0 in reply to Shawn Zheng
    TI__Expert 6985 points
    Hello Kes! We are trying to move customers to some of our newer open-loop devices like the TAS5733/51 or 53, or even our newer closed loop amps like the TAS5780/2. Is there any potential with these? They are easier to support. Thanks, Jeff
  • 0 in reply to Jeff Kohnle
    TI__Expert 6985 points
    Hello Kes! Is this still open for you, or can we close this? Thanks, Jeff