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Setting AM Avoidance for TAS5558

Other Parts Discussed in Thread: TAS5558, TAS5538

Dear Sirs,

My customer asked me that resister setting of AM Avoidance for TAS5558.

He had tried some below settings.

0xDE  0x00 0x10 0x07 0x11

0xDE  0x00 0x10 0x08 0x37

0xDE  0x00 0x10 0x12 0x15

But there was not change PWM Fequency.

So, please let me know how to set AM Avoidance for TAS5558.

Best Regards,

Y.Hasebe

  • Hi, Hasebe-san,

    Sorry for the late response, my colleagues are pretty busy these days, but they will be able to get back to you soon. 

    Best Regards,

      -Diego Meléndez López
       Audio Applications Engineer

  • Hello Hasebe-san,

    We are looking into this issue and will let you know when we have more information.

    For our reference, are there any other registers the customer is writing?

    Best Regards,

    Matt

  • Hello Matt-san,

    Thank you for your reply.
    Register that they has set for AMAvoidance is no other.
    Rather, they'd like to hear how to set up and conditions of AM Avoidance.
    So please let me know how to set up and conditions of AM Avoidance.

    Best Regards,
    Y.Hasebe
  • Hi Hasebe-san,

    Please reference this post on AM Avoidance for TAS5538. The TAS5558 works the same way. You enter the tuned frequency of the radio  and select the IF frequency. The device internal algorithm will check the PWM frequency against the tuned frequency and adjust the PWM frequency accordingly, if it risk interfering with the RF signal.

  • Hello Damian-san,

    Thank you for your reply.

    Then I can't access to  post on AM Avoidance for TAS5538.

    Also I don't have datasheet of TAS5538.

    Cloud you please send to me them.

    By the way, I checked below description of TAS5558 datasheet .

    Is this the same as TAS5538?

    Best Regards,

    Y.Hasebe

  • Hello Damian,

    I summarized AM avoidance of TAS5558 following attachment referred to TAS5538 E2E and SLEA040.

    AM Avoidance of TAS5558.pptx

    What Hasebe-san wants to know is how to eable AM avoidance and how to set 0XDE registers.

    as I mentioned in attachment, if I follow SLEA040 sample, 0xDE is 0x00 14 05 94.

    Does this mean if AM station is 594kHz,  TAS5558 AM avoidance can be enabled using above 0xDE: 0x00 14 05 94.?

    in additon, TAS5558 has two type of AM avoidance mode at D24 in 0xDE

    1.Use Frequency Scaling

    2.Use Sampling Rate Conversion Mode

    could you let us know the function of D24 and how to select D24 bit?

    Thanks,

    Regards,

    Kai

  • Hello Nomiyama-san,

    Yes AM avoidance can enabled using 0xDE = 0x00 14 05 94. This selects:

    • frequency scaling of the APLL for AM avoidance,
    • Enables AM mode, select sequence 4,
    • selects IF frequency 455kHz (of the AM reciever in the radio) 
    • uses BCD for tuned frequency and
    • set the AM tuned frequency to 594kHz

    The Sequence:

    1) Test order  8*Sample Rate, 7* Sample Rate, 9*Sample Rate, 6* Sample Rate

    2) Test order  8*Sample Rate, 9* Sample Rate, 7*Sample Rate, 6* Sample Rate

    3) Test order  9*Sample Rate, 8* Sample Rate, 7*Sample Rate, 6* Sample Rate

    4) Test order  7*Sample Rate, 6* Sample Rate, 9*Sample Rate, 8* Sample Rate

    These are the selected order of the PWM frequency used in AM avoidance algorithm testing. If first fail test then next PWM frequency is tested until a passing PWM frequency is found.

    Frequency scaling is discussed on page 107 of TAS5558 d/s.