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TLV320AIC3263: Layout Recommendations, MCLK and pins

Jorge Brenes
Prodigy 20 points
Part Number: TLV320AIC3263
Other Parts Discussed in Thread: TLV320AIC3262

Dear Sir/Madame,

I have some punctual questions about TLV320AIC3263.

  • In the TLV320AIC3263 datasheet and your reference guide there are no PCB layout recommendations, can you provide me with a document if you have one or can I use the recommendations provided in the TLV320AIC3262 datasheet?
  • An approach recommended in audio forums for the MCLK is use a low jitter clock. What jitter value (ps) do you recommend for the clock? Is it possible to supply only one crystal or is it better to use the crystal/oscillator combination?
  • Can I not supply IOVDD2 and IOVDD3 if I don't use ASI2, ASI3 and GPIO 3 and 4? Or is it mandatory for the codec works properly?
  • In my customer design I am going to use two codecs, is there any problem if I use ASI1 of both codecs?
  • I understand if an input is not used, AC coupling to GND by 0.47 uF capacitor is recommended to improve noise performance, but why is it necessary to change the recommended input capacitor in the typical configuration from 1 uF to 0.47 uF?
  • If I don't use IN1L/Aux1 and IN1R/Aux2, is there any problem if I apply AC coupling to GND? MICBIAS_EXT and MICDET pins, which are connected to IN1L/Aux1, can be connected after the 0.47 uF capacitor to GND?
  • Can I leave the MICBIAS pin floating?

Best regards, 

Jorge Brenes.

  • +1
    TI__Mastermind 48855 points

    Hi Jorge,

    1) Yes you can use the same layout guidelines. The parts are very similar so the same advise applies.

    2) 100ps is our rule of thumb limit. Beyond that, THD+N degradation can be expected. It's hard to say which is better between a crystal vs crystal oscillator. Both are fine however and whichever you pick is dependent on your application and design considerations.

    3) It's best to not leave supply inputs floating. I recommend shorting IOVDD2 and IOVDD3 to IOVDD1. 

    4) There's no problem in two devices sharing an ASI bus. Check section 2.9.5 of the application reference guide for more details.

    5) The capacitor values are made with different considerations in mind. The 1uF cap has to support a typical input signal while the 0.47uF cap to GND only has to support/filter spurious noise in the ground plane.

    6) If IN1L/Aux1 and IN1R/Aux2 are unused, it is recommended to AC couple to ground, like your last question brought up. If IN1L/IN1R are unused MICBIAS_EXT and MICDET pins can be left floating and their respective features disabled.

    7) MICBIAS can be left floating if it has been set to tristate mode. It also has an option to be set to GND which lets you tie MICBIAS to GND.

    Best regards,
    Jeff McPherson

  • 0 in reply to Jeff McPherson
    Prodigy 20 points

    What ppm for the crystal do you recommend?

    Best regards,

    Jorge Brenes

  • 0 in reply to Jorge Brenes
    TI__Mastermind 48855 points

    Hi Jorge,

    Because it is an input signal, we don't characterize a tolerance range. The bigger constraint is the I2S timing constraints listed in the datasheet. We've seen devices accept a wide tolerance, but we can recommend +-10% as a rule of thumb.

    Best regards,
    Jeff McPherson