• State TI Thinks Resolved
  • Locked Locked
  • Replies 4 replies
  • Answers 1 answer
  • Subscribers 46 subscribers
  • Views 413 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

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.

DAC11001A: Combining output of 2 DACS

Nanjunda M
Expert 2485 points
Part Number: DAC11001A

Hi,

We are using 2 DAC11001A in our design. We are using the outputs as fine and course values for the final output.

The reference voltage of one device is 1V and the other DAC is 2V. We want to combine these two outputs directly by shorting the two outputs.

So is it correct to short the two for combined output? Is there any reverse voltage protection present in the DAC?

Please let us know ASAP.

Thanks & Regards,

Nanjunda M

  • 0
    TI__Mastermind 19066 points

    Hi Manjunda,

    Since DAC11001A is unbuffered DAC I assume you have buffer for two DAC's and shorting those. In that case DAC side I wont see any issue.

    Can you please share your schematics? If you are not comfortable in posting e2e, we can take this conversation over email.

    I need to know what exactly you are trying to achieve before I can comment on the query shorting unbuffered DAC's together.

    Regards,

    AK

  • 0 in reply to Akhilesh K
    Expert 2485 points

    Hi Akhilesh,

    At present we do not have a buffer planned at the output of each DAC.

    We are using this combination of DACs to archive a course and fine tuning mechanism for one of our DAC applications.

    If we want to connect the output of 2 DAC11001A DACs directly by shorting, what are the things we should be taking care of?

    Thanks & Regards,

    Nanjunda M

  • 0 in reply to Nanjunda M
    TI__Mastermind 19066 points

    Hi Manjunda,

    No reverse voltage protection is present in the output stage of DAC11001A.

    Let say one DAC is at 2V and other is at 0V (I am considering worst case here). You can model DAC output stage as voltage controlled voltage source with DC output impedance of 2.5 Kilo Ohms.

    In this case, your output voltage will be sitting at approx mid scale because now the network will be essentially 2V in series with 2.5K and another 2.5K to ground.

    So your output will be sitting at 1V approx . This will gain depends on the matching of the output impedance of two DAC's which can vary depending upon process parameters.

    As such we dont recommend usage of DAC in this way. Have a buffer and add series resistor to the output of buffer and short two outputs.

    Regards,

    AK

  • 0 in reply to Akhilesh K
    Expert 2485 points

    Hi Akhilesh,

    Thanks for the inputs.

    Regards,

    Nanjunda M