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TPA311xD2-Q1 Amp IC & AM Radio

Alan Peterson82
Prodigy 10 points

I received the announcement and data sheet for the new TPA311xD2-Q1 Analog Input Class D amp IC and have a concern.

Pgs 17 and 18 explain how to minimize interference to AM radios via connections to  certain pins. What I'm not understanding is this:  given how the pins work to minimize EMI only on certain frequencies ranges within the BC band, will there be interference anyway on some portion of it? Or am I reading the table incorrectly?

I work in radio broadcasting, and I see any kind of local interference to the band as harmful. Especially since this IC is being targeted for automotive applications, and AM is already not doing well in the car anymore.

  • 0
    TI__Guru**** 189401 points
    Hi, Alan,

    Welcome to e2e, and thanks for your post!

    As for your specific question, those two pins change the switching frequency. Basically, the associated table will put the harmonics outside of the AM channel the radio is tuned to. This will minimize interference when using this amplifier with AM stations in a car.

    Let us know if you have any further questions!

    -d2
  • 0
    TI__Mastermind 45085 points

    Hi Alan,

    We have three clock or switching frequencies available on the TPA311xD2-Q1.  In an head unit, we know the AM frequency and the amplifier switching frequency.  The controller in the head unit should change the amplifier switching frequency so that the 2nd harmonic and 3rd harmonic of the switching frequency are not detected by the AM receiver and produce a tone in the speakers.