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PGA970: Phase detection with PGA970 evaluation board

nick marietti
Prodigy 30 points
Part Number: PGA970

I am trying to use a PGA970 evaluation board with a 4-wire RVDT sensor and I am unable to see a change in the phase angle when looking at the ADC capture from the provided GUI. Based on what I am seeing I assume that I have not correctly configured the device but I am unable to find any information in the data sheet that would lead me to the answer.  I have also searched the TI forums and found this post which seems to have the exact same problem but unfortunately there is no posted solution.  

I have attached a screen capture of the ADC and Phase plot from the GUI as well as my current configuration that I have saved off in case they are useful in helping me to troubleshoot this issue.

Configuration.cfg

  • 0
    TI__Guru**** 180821 points

    Hi Nick,

    Welcome to our e2e forum!  Our PGA970 support personnel are out of the office this week and should be back on Monday.  We'll try to get you some answers to your query then. 

  • 0 in reply to Tom Hendrick
    Prodigy 30 points

    Hello Tom,

    Thank you for the response and I will look for that early next week.

  • 0 in reply to nick marietti
    TI__Mastermind 18900 points

    Hi Nick,

    I was hoping to solve the issue before responding but the short of it is I can't replicate the issue in the lab. The GUI seems to track phase correctly for me.

    This is led me on a bit of a rabbit hole to see how the phase is actually displayed in the GUI. My current thought is that it looks like the GUI uses PHxDATA[0:31] from demodulation. And the data looks good from the ADC and correlates pretty well. There really isn't much info phase extraction so I can't make a comment how it might be causing an issue.

    I will say I don't have RVDT in the lab and I really just use a sine generator. I would recommend trying that lab to see if the issue persists. That being said, we've sold a lot of PGA970s and know of customer who use the phase so I don't see an obvious reason why a RVDT would cause an issue. 

    Best,

    -Cole

  • 0 in reply to Cole Macias
    Prodigy 30 points

    Hello Cole,

    Is there any configuration that I would need to make on the GUI in order to enable phase angle output?  Would it be possible for you to post your register configuration here so that I can compare it to what I am using?

    Thanks,

    Nick