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ADS1216: How to calculate "OCR/FCR"

Takumi Suzuki1
Mastermind 8610 points
Part Number: ADS1216

Hi,

I would like to ask you a question about the OCR/FCR of ADS1216.

I have studied application report "SBAA099" as below.

http://www.ti.com/analog/docs/litabsmultiplefilelist.tsp?literatureNumber=sbaa099&docCategoryId=1&familyId=2019

About FCR, we can get it by equation (2) (page 5), "FSR = h1FFFFFFFFFFF/(Digital Filter Output - OCR)".

On the other hand, there is no concrete description to calculate about "OCR", I suppose. 

My undrstanding is that OCR is just mean data of "4 digital filter output data".

Is my idea correct?

Thank you for your advice.

Best Regards,

  • 0
    TI__Guru* 97945 points
    Takumi-san,


    The OCR value represents the offset voltage as a value coming out of the digital filter. Because of this, the value will scale with the decimation ratio.

    The best way to describe it would be to look at equation (8) in the application note. The OCR represents a voltage, based on the reference and the DFG. You can see with Examples 2 and 3, that the OCR value stores the value based on a real offset voltage and is later scaled by the FSR register.


    Joseph Wu
  • 0 in reply to Joseph Wu
    Mastermind 8610 points

    Hi Joseph-san,

    Thank you very much for your reply!

    I'm sorry I missed equation (8)..

    Let me study it.

    Best Regards,