AD7147 offset


In the AD7147 datasheet on page16 it shows a diagram of how the POS_AFE_OFFSET and the NEG_AFE_OFFSET affect the CDC.

Suppose I have a single CIN connected to the positive end of a conversion stage. if the measured values are too low, then increasing the POS_AFE_OFFSET would make it better. However if the values are too high and the POS_AFE_OFFSET is already at 0, so I can use the NEG_AFE_OFFSET_SWAP bit to use the NEG_AFE_OFFSET to decrease the measured values toward midscale.

Am I correct?

(about the ability to use the NEG_AFE_OFFSET as a negative offset to the positive feed)

thank you.

  • 0
    •  Analog Employees 
    on Mar 5, 2015 2:56 PM

    Hi Ilia,

    Yes, you are correct. When a measurement is above or below the midscale, the positive and negative offset controls are used to bring it back into the correct range. If extra offset is required, the POS_AFE_OFFSET_SWAP bit will apply the Positive offset to the negative side of the CDC, effectively extending the range of the Negative offset. The NEG_AFE_OFFSET_SWAP does the same thing with the negative offset, applying it to the positive side of the CDC/


  • 0
    •  Analog Employees 
    on Aug 2, 2018 2:57 PM
    This question has been assumed as answered either offline via email or with a multi-part answer. This question has now been closed out. If you have an inquiry related to this topic please post a new question in the applicable product forum.

    Thank you,
    EZ Admin