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Original question:

DAC8741H: xtr115 with DAC8741H

XTR115: XTR115

sreekar goud
Prodigy 30 points
Part Number: XTR115
Other Parts Discussed in Thread: ISO7021

Tool/software:

Hi 

I want to use 2 XTR115 to the same 24V loop. Need to get two 4-20mA outputs. But we am facing issue when we increase the value in XTR115_1 we can see a change in XTR115_2.

Even after placing ISO7021 Low powered digital isolator which can be used in two wire loop powered . My issue is not getting solve. 

Can you please let us know how to isolate both PWM signals so that we can able to read both outputs independently.

And in both the cases my current should not excide more than 3mA.

Regards

Sreekar

  • 0
    TI__Genius 15390 points

    Hello Sreekar, 

    I saw there was a duplicate thread from you with the same information so I have deleted the second thread. Please let me know if I had missed something in the duplicate thread. 

    For the digital isolator part, I do not believe you need this if you are solely using it to fix the XTR current problem. It may introduce more issues as the isolator needs a ground reference and is currently being tied to the XTR IRET current pins, which cannot be used as GND. 

    Also, could you elaborate why you are using the D-Latch device on the input? I am a bit confused what the purpose of this is in the signal chain. 

    Regards,
    Ashley

  • 0 in reply to Ashley Kang
    TI__Genius 15390 points

    Hi Sreekar, 

    Let me correct my isolator comment, if you are using the Isolator part, the below diagram is the way we recommend to implement it, not by connecting the two Iret grounds. You need to isolate the input to each transmitter in order for the Iret of each transmitter to not have grounding issues.

    Regards,
    Ashley