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aic3254 differential stereo output

Christian Brandoni
Prodigy 50 points


We are willing to use aic3254 in our design and we need some clarification on the aic3254 line out and headphone out.

Watching the block diagram of the chip,the 2 output seem having the same characteristics(identical amplifier before the pin output).

The only difference we found was in the reference schematics used in the EVM,where different resistors and capacitors are used for them.

Would be possible to configure them with the same electronics and use them as double purpose  line out/heaphone?I mean each stereo output should be able to act as both.

And by doing so would we be able to have a stereo differential output?If the line out and headphone out have different characterstics we won't be able to do so(the left and right signals will be different)

 

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  • 0
    Prodigy 50 points

    mmm,I just read that the line driver can go from 600 to 10K ohm.

    So they are actually different.Too bad.We'll modify our design then.

  • 0 in reply to Christian Brandoni
    TI__Mastermind 46195 points

    Hello Christian,

    That is correct. The AIC3254 line outputs are meant to drive high impedance loads. Still, the HPL/R could be sourced by the left DAC +/-, and LOR/L could be sourced by the right DAC +/- to drive a high impedance stereo amplifier.

    Regards,

    JA

  • 0 in reply to J-
    Prodigy 50 points

    Thanks Arbona for your help,that feature would be very interesting.

    But I have a worry,since the audio drivers are different won't we have different audio response on each channel?

     I mean the headphone driver may produce a sound with different characteristic than the line driver with the same settings and load.

    Other than SNR,THD,what worry me is that the generated sound may be remarkably different,like for example one channel warmer than the other or with different volume. 

  • 0 in reply to Christian Brandoni
    TI__Mastermind 46195 points

    Hello Christian,

    I understand your concern. THD, SNR, amplitude and response should be similar when both are driving line loads. Coloration is mostly due because of response and/or THD differences.

    You might also want to take a look at our other miniDSP devices, such as the AIC36 (http://focus.ti.com/docs/prod/folders/print/tlv320aic36.html) which features four single-ended, ground centered headphone amplifiers, as well as two differential line drivers. See Figure 5-1 on page 21 of http://focus.ti.com/lit/ds/symlink/tlv320aic36.pdf for details on differential line driver connections.

    Regards,

    JA

  • 0 in reply to J-
    Prodigy 50 points

    I had a look at AIC36 before,and it was our previous choice,but it seem it is not available yet for purchase.
    Also since we will be buying from the Chinese distributor and they seem always behind the rest of the world on TI products,it may be very hard to obtain a very new codec.
    Even for AIC3254 we are told to wait October and we are forced to order the EVM and the samples from the USA distributors to quicken the process.