Help me interpret two datasheets (got'em in thread) to interface audio between chips

Discussion in 'General Electronics Chat' started by Steve C, Aug 5, 2009.

  1. Steve C

    Thread Starter Active Member

    Nov 29, 2008
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    0
    Hi guys,

    I'm trying to connect two audio processors and for space reasons need to eliminate the output boards. This gives me direct access to the DACs and ADC's via IDC connector.

    So the easiest thing I can do is just plug the outputs from the DACs of processor 1 into the ADC's of processor 2. but I don't know if that is going ot cause me problems, and the datasheets seem to me to indicate that that WOULD be a problem.

    here are the chips in question:

    http://www.akemd-eu.com/library/DS/AK5383.pdf

    http://www.asahi-kasei.co.jp/akm/en/product/ak4393/ak4393_f02e.pdf

    So, the 4393's say the are ~2.5 volts max out and the 5383 says it is .3 volts max in, if I am reading things properly.

    Am I reading things properly? Doesnt seem right for a chip to take audio in at +/- .3 volts max. Would love some advice on the matter.
     
  2. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
    282
    You are going to go from a digital file to audio and then back to digital. It might be easier to just transfer the audio file as is.
     
  3. Steve C

    Thread Starter Active Member

    Nov 29, 2008
    86
    0
    might be, but that requires soldering directly to the boards which I prefer not to do. What's nice about this method is that I have access to the audio out pins through an IDC connector. This affords me a much more robust connection.

    an audio chain free of DACs is nice, but doesn't afford me any benefit if there are digital signal reflections and unreliabilities caused by stressed or poor connections. I can also guarantee that even with additional DA conversions, the biggest distortion producers in the system will not be as a result of the dacs, but elsewhere.

    So I'm not too worried about it.


    oh wait wait wait. The datasheet says VA+.3. So I should be good to the chip shource, right? If the chip is powered by (random number here) 3.3Vdc, I'm good from -.3v to +3.6v. right? am I reading this right now?
     
  4. Steve C

    Thread Starter Active Member

    Nov 29, 2008
    86
    0
    I was talking to someone else awhile ago that suggested transferring digital information is suceptible to reflections; moreso than analog transmissions. While this isn't the sole reason for wanting to transfer the audio this way, it's another.

    Does anyone else see any reason I can't just run the audio straight fron one side into the other with nothing in between? I can't see any reason I can't do this.

    I guess I should mention these chips reside on two separate circuit boards. Two separate DSP, in fact. directly wiring them together could save a huge amount of wiring mess and would be really easy as the AOUT and AIN lines are connected directly to IDC connectors on the boards.

    ----

    I forgot to mention I want to drive TWO of the ADC's with the outputs from one DAC. Seems like this would be OK too. the output is 3.5A capable, and the input impedance is min 8kohm. So I should be golden, right? seems like I have a factor of safety of 5 on the current outputs of the DAC. Is there anything more to this I am missing?
     
    Last edited: Aug 14, 2009
  5. Steve C

    Thread Starter Active Member

    Nov 29, 2008
    86
    0
    So, if folks are interested, it works just fine, I get audio.

    And a TON of distortion. maybe overdriving the adc's? doesnt matter. It's not a workable solution.

    Thanks guys!
     
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