Help regarding ADE7753 measurements

  1. Noman Bashir
    Noman Bashir
    Hello everyone. I have been working on energy metering IC ADE7753 for our project. Initially,
    I was stuck on how to use ADE7753 with shunt resistance but then somehow I figured it out.
    I am writing this post so that some of you may comment whether the approach specified below is right or wrong.
    I intended to use ADE7753, a single phase energy metering IC, for monitoring the power of load.
    After initial thought process, I decided to use shunt resistor as a current sensor with ADE7753.
    Once I read the whole datasheet, I was unable to get a clear cut answer to the question
    "How to incorporate the value of shunt resistance into calculations of power measurement?"
    Because normally when we use shunt resistance, we measure voltage
    drop across it and then calculate current by using ohm's law I = V/R. Here, voltage across shunt
    resistance was being applied to the channel one of ADE7753, across V1P and V1N, but there was no
    mentioning of how this voltage will be converted into current. I tried to search different forums
    but couldn't find a clear solution to my problem. There were some posts regarding the same
    problems but experts only suggested to read the datasheet rather than giving an answer over there.
    Also, if someone who posted the question figured out the solution at some later stage, he didn't
    post the solution on his/her post so that thread could be closed.

    Initially my hypothesis regarding the setting of the ADE7753 was that I may have to input the value of
    shunt resistance into the IC by setting some registers . After finding no register for such setting,
    I did an in-depth study to get a further insight into the working of the ADE7753. I came across the
    procedure regarding calibrating the IC with known load first and then using the calibration data for
    future measurements of unknown loads.

    During the calibration phase, we apply a known load to ADE7753 and calculate different constants like
    Wh/LSB and VAh/LSB which take into account the value of shunt resistance by default. There will be a
    specific constant for a specific value of the shunt resistance used and these constants can be used
    to convert register contents into some meaningful data as long as shunt resistance, for which they
    were calculated, remains the same. During normal operation, we read the register values through serial
    interface of ADE7753 and then use these constants to convert these values into meaningful data like
    Watt Hours and Volts etc. So this is my understanding of the working of ADE7753 with shunt resistance,
    kindly let me know if my approach is wrong.
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