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DDC114: Schematic review

Atul Bhakay
Genius 3205 points
Part Number: DDC114

Hi, this is regarding DDC114

I chose the formula on page no 24 because I collect data after conversion signal toggles.

I checked with the formulas you suggested on page no. 23 and 25. As per the calculation I found that if my Tint >355.125us I can connect more ddc in daisy chained format. Correct if I m wrong and explain the impact if my Tint >355.125usec.

Regards

Atul

  • 0
    TI__Prodigy 640 points

    Hi Atul,

    Please review the already provided answer on the other thread:

    Regards,
    Simon

  • 0 in reply to Saimon
    Genius 3205 points

    Hi Simon,

    I chose to read data after CONV toggle because I thought I could reduce the integration time that way i.e. when conversion of Side B starts I could read data of Side A. Please advice which way could help me reduce integration time , reading before CONV toggles or after CONV toggles.

     

    And also u suggested that number of daisy chained DDC 114s will also depend on when I collect data. So please suggest when can I connect more DDC 114s i.e. will I be able to connect more DDC 114s if I read data before CONV toggles or will it be more if I read data after CONV toggles.

    Regards

    Atul Bhakay

  • 0 in reply to Atul Bhakay
    Genius 3205 points
    Hi Simon,
    Awaiting your reply
  • 0 in reply to Atul Bhakay
    TI__Prodigy 640 points
    Hi Atul,


    Excuse the delay.
    It's ok that you chose reading after the CONV toggle if your integration time is small.
    Other than that, if you review the formulas, you'll see that for 16 devices, in this case it won't matter when you do the reading.
    (You can see that the numbers that are provided in the examples of the datasheet are in the order of 40-80 DDC114s for the given clock, CLK=4MHz and DCLK=10MHz).
    If you have doubts deciding for an integration time, you should also consider the type of input (current) you have and not just the number of DDC114s that you want to daisy chain together.

    Let me know if you have any further questions.
    But, please do keep them on the same thread if they're related and only open new threads for new issues, should they arise.

    Regards,
    Simon
  • 0 in reply to Saimon
    Genius 3205 points

    Hi Simon,

    Thanks for your reply. I am really grateful to you for all your replies. One more query :-

    Can u please elaborate how type of input current should decide the integration time? Please advice

    Regards

    Atul Bhakay

  • 0 in reply to Atul Bhakay
    TI__Prodigy 640 points

    Hi Atul,

    As the DDC114 is a current integration device, two factors will adapt to the type of current present at the input: the integration time, Tint, and the capacitor feedback network, Cf, which is set with the range configuration. That´s why you see different charge values on the device specs (see DDC114 DS page 3) according to the range (capacitor) set. More on the device operation, on the DDC114 datasheet page 9.

    Regards,
    Simon