• State Resolved
  • Locked Locked
  • Replies 1 reply
  • Subscribers 47 subscribers
  • Views 331 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

XTR117: Question about the current loop configuration.

Evangelos Psaradellis
Prodigy 20 points
Part Number: XTR117
Other Parts Discussed in Thread: XTR111

Hello to everyone, 

I have one short question regarding the current loop and how is it configured on my own design.

According to the attached image, you can see that the 24V power line is connected directly to the V+ pin and the R_Load is supposed to be connected in the 4to20_Iout. 

Hence, the main current path (4-20mA) is supposed to start from 24V power line, passing through the R_Load and return thought GND. 

However, I am currently testing my board and it seems that without any R_Load being connected, the IC is getting warmed up very fast and the measured current at 24V goes up to 40mA. 

It seems, that the current limit protection has been activated and the IC is striving to keep the current as low as possible Stuck out tongue.

In conclusion, I think that the 24V line shall be connected with the R_Load in series to have a current limiting resistor and then the IC will regulate the current respectively.

At this design it seems that the current is limited only by the IC and for this reason the IC is getting hot. 

Thank you in advance. 

Looking forward for your prompt response!

  • +1
    Guru 318050 points

    The XTR117 is designed for 2-wire loops where the measurement circuit is supplied only from the loop. The IRET pin is the ground of the measurement circuit, but it must be able to float relative to the loop supply's ground.

    In your application, you probably want a 3-wire transmitter like the XTR111.