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TAS2557: Using TAS2557 at 8KHz sampling

Part Number: TAS2557

Customer can get EVM to work well at 48KHz. In some use case, customer requires 8KHz sampling. 

1) Is there a block diagram of the clocking structure of the TAS2557. The block diagram on page 18 of the datasheet just shows the 'Programmable PLL' with no more information.

2) Can provide full list of registers? At the moment the configuration we are using from the eval board is programming many register that are not in the datasheet.

Customer is using the BCLK of ASI1 as clock input. It goes into PLL and the output of the PLL is used as the MAIN_CLK for the device. We guess we need to usePLL to get to 12.288MHz but can't see anywhere to set it.

  • Hi Eddie,

    8kHz sample rate is supported, it can be selected in End System Integration panel.
    However in order to use the device in smart-amp mode, the source clock must be at least 1.36MHz, so BCLK frequency for 8kHz sample rate is most likely not high enough; it can still be used in ROM mode though.
    Most of the clock settings registers are hidden and configured from PPC3 End System Integration tool to prevent errors in the clocking scheme. However if you still want to know more details on these registers I can gather some info and share internally.

    Finally, 8kHz sample rate in smart-amp mode is supported, if they can provide at least 1.36MHz clock on MCLK or BCLK, and it should be configured by using End System Integration.

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

    Please send me more details of the registers via email separately. Customer is advanced user with experience on older TAS2xxx family of products.

  • Eddie,

    I'll get this data together and send it through e-mail.
    I'm closing this thread on e2e for now.

    Best regards,
    -Ivan Salazar
    Applications Engineer - Low Power Audio & Actuators
  • When we try to create configuration for ROM modes there isn't an option for 8kHz. I've attached 2 photos (with screenshots the options disappeared) showing we can only select 48kHz and 44.1kHz in ROM modes.

    We can send data to the part at 1.536MHz so in theory we should be able to get 8kHz working in all modes.

    Note: Screenshots sent via email

  • Eddie,

    I have replied to you via email.

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