• State
  • Locked Locked
  • Replies 3 replies
  • Subscribers 31 subscribers
  • Views 1623 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

PCM58P output dc offset

Ken Ealey
Prodigy 20 points

I have a PCM58P Burr Brown DAC that I'm hoping someone might be able to help me out with. My problem involves the DC offset at idle of the single output pin, it's not 0 volts and is causing post dac circuitry to operate lopsided. I'm working on an audio DAC unit and it has 2 chips for 2 channels. One of the units has offset within + - 10mv, which corresponds to the bipolar zero error figure, but I'm not sure if this spec is the one I should be looking at. The other chip has like a .24volt offset, and is thus creating a larger offset at the post dac circuit output. Is this normal operation? I'd think more of a 0 volts dc offset would be normal. Can and do these outputs on these (or other) dac chips breakdown and lose spec? The overall dac unit does work, but only because some DC blocking caps were in place at the final output. Needless to say, the post dac circuit on the .24v offset chip is operating lopsidedly, which is really not a good thing. I wouldn't think I/V converters are meant to operate in this fashion. Think I got everything.

  • 0
    TI__Guru**** 189401 points

    Hi, Ken,

    I don't recognize that part number. it could be one of two things:

    1) it's older than dirt and we deleted it off our website,

    2) you gave us the lot code or something (I doubt it as PCM is our normal prefix for BB Audio)

    3) it's a custom device we made for a particular customer and can't disclose information about it due to the development agreement with the customer.

    -d2

  • 0 in reply to Don Dapkus
    Prodigy 20 points

    Thanks for speaking up Don. The pcm58 is indeed an older dac, and can be found in a number of cd players and stereo dacs. If you don't know anything about  that particular one, perhaps you can still help. Is it typical for dac chips to exhibit a near 0vdc offset at their output pins, especially as measured in open circuit? Since this one is meant as a current source to drive I/V converters, you can see my concern. My guess is the chips with excessive offsets are damaged somehow, and if so, then I'd like knowing how this damage is created. If more info was given on data sheets, perhaps I could figure it out or get a clue. Given black box info doesn't help much. Are there any dac chips that do have larger dc offsets?

  • 0 in reply to Ken Ealey
    TI__Guru**** 189401 points

    Hi, Ken,

    You might be better suited to posting your questions at DIY Audio; I'm sure one of the guys over there is familiar with this device.

    -d2