• State TI Thinks Resolved
  • Locked Locked
  • Replies 2 replies
  • Answers 1 answer
  • Subscribers 46 subscribers
  • Views 1922 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.

DAC DAC8814: To use current outputs as complementary pair for differential signalling

Vladimir Ivchenko
Prodigy 20 points
Other Parts Discussed in Thread: DAC8814

End application: Temperature controlled precision DAC

Dear experts, can you please advise if we can use DAC8814 DAC's current outputs IoutX and AgndF+AgndX as a complementary pair for creating an output differential signal? We are looking for an output arrangement similar to the one described in Application Report SBAA150.

The pair AgndF+AgndX is intended to be connected to ground according to datasheet. We understand that voltage AgndX to DGND must be less than +/- 0.3V. So we plan to keep output pins IoutX, AgndF and AgndX at the ground potential.

What implications may prevent us to connect AgndF and AgndX wires together and use them as a second current output complementing the main current output IoutX?

Background: We are looking for a possibility to obtain very low noise well below the quantization noise of DAC. We consider the differential signalling as a measure to achieve a lower noise.

  • 0
    TI__Mastermind 46290 points
    Vladimir,

    If I follow your interests correctly I think this approach is reasonable as there is a separate DGND pin which is where the supply current for the digital switches used in the R-2R ladder would go so on IOUT_X and AGND_X you would see a complementary pair of current sources. One caveat though is I'm not sure how well matched the currents will be from channel to channel - not sure if that would be a problem for your use case. Generally we can ratiometrically match the resistors in each MDAC circuit but off the top of my head I'm not sure how well matched one channel will be to the next since that is not intentionally controlled.
  • 0 in reply to Kevin Duke
    Prodigy 20 points

    Kevin, thank you for the prompt reply! Channel to channel matching is not the issue in our design. I hope this is the only caveat in the planned architecture of the DAC usage.