XTR117: How to use four piece of XTR117 in one of schematic, and they're the common signal GND

user1896782

Part Number: XTR117
Other Parts Discussed in Thread: XTR116, XTR111, ISO7310C

I have a question while design XTR117. If there's one XTR117, it can output 4~20mA current regular. However, if there're four piece of XTR117, the output of the current will be abnormal.

It looks like they're interfering with each other.

(1) This is one of the four pieces

(2) This is the all

over 3 years ago

0 kai klaas69 over 3 years ago

Guru 140200 points

Hi,

this issue has already been discussed here for many times. Make a search for "XTR116" and "XTR117". See this one for example:

The individual pin 3 (Iret) of each XTR117 must be galvanically isolated from each other. Otherwise the associated currents interfere with each other.

I would think about using the XTR111 instead of XTR117.

Kai

0 Raymond Zhang1 over 3 years ago in reply to kai klaas69

TI__Mastermind 47516 points

Hi user1896782,

Thanks for Kai's reply.

Here is the common issues with 4-20mA 2-wire transmitter mistakes. 4-20mA 3-wire transmitter in XTR111 does not have the constraint.

Best,

Raymond

0 user1896782 over 3 years ago in reply to kai klaas69

Prodigy 50 points

I see, that means use diodes to isolate simply is not the right way. Then, can you give me some useful chips to isolate these XTR117? Thank you.

0 user1896782 over 3 years ago in reply to Raymond Zhang1

Prodigy 50 points

I hear there's 2/3/4-wire. what's the difference between the three of them?

0 Raymond Zhang1 over 3 years ago in reply to user1896782

TI__Mastermind 47516 points

Hi user1896782,

The attached is 4-20mA ppt for the transmitter topics. Please pay attention to the 4-20mA return path in different transceiver configuration.

/cfs-file/__key/communityserver-discussions-components-files/14/7888.4_2D00_20mA_5F00_Basics.pdf

4-20mA 4-wire transmitter type: 4-20mA signals flows through two separate cable wires between the transmitter and receiver. The two power sources for transmitter and receiver are totally isolated.

Best,

Raymond

0 kai klaas69 over 3 years ago in reply to user1896782

Guru 140200 points

Hi,

carefully compare the circuits shown in the datasheets of XTR111 and XTR116/7. Shift your attention to the signal and power grounds :-)

Kai

0 user1896782 over 3 years ago in reply to Raymond Zhang1

Prodigy 50 points

Thank you very much~

0 user1896782 over 3 years ago in reply to kai klaas69

Prodigy 50 points

Thank you for answering~

0 kai klaas69 over 3 years ago in reply to user1896782

Guru 140200 points

Good luck :-)

Kai

0 Raymond Zhang1 over 3 years ago in reply to Raymond Zhang1

TI__Mastermind 47516 points

Hi user1896782,

We also have single channel digital isolator, ISO7310C. If you use it in the front end of XTR117, your issues will be solved as well.

https://www.ti.com/lit/ds/sllsei8d/sllsei8d.pdf?ts=1594389363792&ref_url=https%253A%252F%252Fwww.google.com%252F

Best,

Raymond

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XTR117: How to use four piece of XTR117 in one of schematic, and they're the common signal GND