• State Resolved
  • Locked Locked
  • Replies 5 replies
  • Subscribers 29 subscribers
  • Views 215 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

TAS2505: variation accuracy of the offset voltage

Ryotaro Fukui
Intellectual 2345 points
Part Number: TAS2505

Hello,

My customer has several questions about the test result of TAS2505.

The customer measured TAS2505 using the evaluation board, and with CM=0.9V, Speaker Amplifier Volume +12dB and SPKVDD = 5V, voltage of SPKP and PPKM was 2.5V. From this result, they estimated that the offset of the speaker amplifier in the output stage is 1/2 of SPK VDD. Is it correct?

If it is correct, the customer also wants to ask these farther questions:

  • What is the variation accuracy of 1/2 offset voltage? (Accuracy when generating 1/2 from SPK VDD)
  • The relationship between CM = 0.9V and the above-mentioned 1/2 voltage. Where in the circuit are those voltages switching?

I'm looking forward for your reply.

Best Regards,

Ryotaro Fukui

  • 0
    TI__Guru* 84915 points

    Hello, Fukui-san,

    The configured CM level is actually not related to the Class-D driver. This is the common-level mode for the headphone driver. If you enable the headphone driver, you should see this level for a zero input.

    Could you provide a scope capture fo the output lines with this SPKVDD/2 level? Are you using a zero input in order to see the Class-D activity? I think you should have a zero output instead of a 2.5V offset and the outputs should be switching from SPKVSS to SPKVDD.

    Could you also share the schematic and registers configuration, please?

    Thank you.

    Best regards,
    Luis Fernando Rodríguez S.

  • 0 in reply to Luis Fernando Rodriguez S.
    TI__Intellectual 2345 points

    Hello Luis-san,

    Thanks for the quick reply. Let me confirm my understandings.

    In order to know the variation accuracy value of the offset voltage, I have to provide you, scope capture of output lines, schematic, registers configuration and confirm if they are using input 0V for their previous measurement. How should I send you these data? Is email better, or should I post it here?

    And I would also like to know what factors affect the offset and its variation value. Does it change depending on the SPKVDD value or CM voltage?

    Thanks for the help.

    Best regards,

    Ryotaro Fukui

  • 0 in reply to Ryotaro Fukui
    TI__Guru* 84915 points

    Hi, Fukui-san,

    Please take a look at my responses below:

    How should I send you these data? Is email better, or should I post it here?

    You may contact me via email in case this is sensitive information that cannot be shared in a public forum.

    And I would also like to know what factors affect the offset and its variation value. Does it change depending on the SPKVDD value or CM voltage?

    Actually, the Class-D driver shouldn't have an offset level unless the customer is providing a constant value via I2S. Even if the SPKVDD and CM voltage levels are modified, the Class-D driver depends of the I2S data.

    Please let me know if you have additional comments on this.

    Best regards,
    Luis Fernando Rodríguez S.

  • 0 in reply to Luis Fernando Rodriguez S.
    TI__Intellectual 2345 points

    Hi Luis-san,

    So there shouldn’t be an offset, and output only depends on I2C inputs. Thanks for your response, I am starting to grasp the situation.

    I am currently contacting a customer for additional information. If there is likely to be a lot of data, I would like to continue this discussion by email.

    Best regards,

    Ryotaro Fukui

  • 0 in reply to Ryotaro Fukui
    TI__Guru* 84915 points

    Hi, Fukui-san,

    Thank you for your response.

    Let's continue the conversation via email. I will close this E2E thread for now.

    Best regards,
    Luis Fernando Rodríguez S.