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TLV320DAC3101EVM-U: Setting the output power of speaker by CodecControl - linearisation

user4633449
Prodigy 60 points
Part Number: TLV320DAC3101EVM-U

Hello there, I was trying to understand how the output power of speaker can be set within Codec Control properly. There are some blocks (Analog attenuator and D-class Speaker driver ) which allows you to set some parameters in dB. Problem is that when I was set The Analog attenuator value to -6dB and output drive to +6dB I expected 0dB output amplification (the same like on Vin on input). This setting was working for headphone output (When I was set 0dB to both blocks the result was the same Vrms like on input Vin). I did another setting measurements (see excell attached) but I still don´t know the real transfr function between these numbers and functionality. My goal is to have real setting possibilities for setting the dB amplification/ attenuation. Than maybe something like logarithmic scale from 0 to 100% of full output power.

Thank Youscaling_1.xlsx

  • 0
    TI__Guru* 84915 points

    Hi,

    Thank you for the information you provided.

    Regarding the output measurement, are you using a Class-D RC filter? Something like the one showed in the link below:

    https://www.ti.com/lit/an/sloa107/sloa107.pdf

    In addition, could you verify which register is written when you adjust the Class-D gain and the attenuator? There's an option in the "Command" Window of the GUI that allows to track the changes by recording the I2C activity. You just need to click on the "Record" checkbox to start recording.

    Thank you.

    Best regards,
    Luis Fernando Rodríguez S.

  • 0 in reply to Luis Fernando Rodriguez S.
    TI__Guru* 84915 points

    Hi,

    Excuse me, do you have any feedback on this case? Were you capable to follow my suggestions of my response above?

    Thank you.

    Best regards,
    Luis Fernando Rodríguez S.

  • 0 in reply to Luis Fernando Rodriguez S.
    TI__Guru* 84915 points

    Hi, 

    I'm closing this e2e thread due to the inactivity.

    However, please feel free to post your questions or comments about this case. We will be glad to help you.

    Best regards,
    Luis Fernando Rodríguez S.

  • 0 in reply to Luis Fernando Rodriguez S.
    Prodigy 60 points

    Hi, 

    I apologize for my delay,

    I have another topics on my desk, but thank you for support. I don´t use the RC filter for power measurement

    (this can improve accuracy measurements, I will implement one).

    regarding the I2C recorder, this was also good idea :) I doublechecked the registers meaning and functionalities and I realised also the functionality of whole system.

    Now I know that the Analog attenuator is only used like attenuator (can be used like output level control) for fixed D-class setting which needs to be selected according the required gain slope and range of output level.

    I have only one question...I think for the best result for controlling the speaker volume controll will be to use Analog atenuator register but in this case the analog input of attenuator will need to be somehow unified (I mean to 0.707Vrms signal.) Is it possible to achieve this using the DRC feature? If yes, please give me some advice..What about the maximum digital codes as an input to DAC block (how to unified also this part?)?

    Thank you very much

  • 0 in reply to user4633449
    TI__Guru* 84915 points

    Hi,

    The DRC is a good feature that can help you to maintain a specific output level if the output amplitude is reduced. I recommend to take a look at this document, it contains additional information about how to configure the DRC feature. Let me know if you have additional questions or comments.

    https://www.ti.com/lit/an/slaa446/slaa446.pdf

    Best regards,
    Luis Fernando Rodríguez S.