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Reg => LM49450

Prasath Shanmugakani
Prodigy 30 points
Other Parts Discussed in Thread: LM49450

Hi There,

Presently am using LM49450 DAC, we are getting some noise in the speaker. Moreover, when we measured the clock in speaker, it is more than 250 Mhz

We have the MCLK as 12.3 Mhz. Could you please provide the LM49450 register settings to get the audio in the speakers.

Thanks in advance,

Regards,

Prasath S.

  • 0
    TI__Guru 55556 points

    Please clarify where you measure the 250MHz?

  • 0 in reply to Dominik Hartl11
    Prodigy 30 points


    Dear Harti,

    Thank for you for supporting me :-)

    Sorry for the confusion, we are using a class 'D' amplifier where the output should be 300Khz and now it is 280Khz which is fine now.
    But, the LM49450 inputs are being driven from the ADV7611 Chip.
    Please find the attached image for the input driven from the ADV7611.
    Presently, we are getting the Master clock line as 12.39Mhz.
    For this MCLK, When we set the DAC mode as 10 in 0th register and increase the speaker volume in speaker volume register ( Say 15 ), refer the dump in  LM49450_Dump_Registe.txt of attachements
    we are able to hear noise ( No proper audio ) in the speaker. ( listen the attached mp3 )

    Now we are having the below questions.
    -------------------------------------------------------
    How can we ensure that the proper audio is coming from the ADV7611 in to LM49450 ? Is there any way can we measure the waveform ( 4 lines that act as a input to LM49450 ) in LM49450 chip i2s lines to ensure proper audio data is being driven from ADV7611 chip?
    If the MCLK is 12.3 Mhz, assuming the other three lines are being driven with correct input values, what are the register settings that has to be done on LM49450 chip ?
    Suggest under which Master clock the LM49450 operates well. So that we can set the proper register settings in ADV7611 chip ? Consider if it operates at a MCLK called 'X'' then please provide as the settings for the MCLK 'X' that has to be done on LM49450 chip
    Does MCLK value need to be constant or it can be vary from ADV7611? If it can vary how do we need to handle this in the register settings dynamically ?

    Please find the attached dump, for the register settings being done in LM49450 to hear the noise in the speaker. ( LM49450_Dump_Registe.txt )

    Moreover, see the lines measured in the ADV7611 chips in the attachments

    If you need any more information please let me know

    Thanks in advance.

    Regards,
    prasath S.

  • 0 in reply to Dominik Hartl11
    Prodigy 30 points

    Dear Harti,

    Please find the necessary attachments in the "To Texas"

    Anticipating your early reply.

    Thanks and Regards,

    Prasath S.

    To Texas.zip