XTR117 wrong output current

john Ma

Intellectual 280 points

Other Parts Discussed in Thread: XTR111, XTR117

RIN=27Kohm,

The current in first picture is 23mA, the second is below 100uA. Who can tell me the reason? Thank you very much.

Note: op-chip DAC output is right. It's 0.66V in this test.

over 7 years ago

0 Collin Wells over 7 years ago

TI__Guru 62085 points

Hello,

This looks like a grounding issue since you've drawn the IRET pin of the XTR117 connected to the load and supply GND pin. This is not an acceptable operation of a 2-wire sensor transmitter. Consider modifying your ground scheme as described in the blog posts below, or use a 3-wire transmitter such as the XTR111.

The Basics of 4-20mA Current Loop Transmitters

2-Wire 4-20mA – IRET Can’t connect to Vloop GND

2-Wire 4-20mA – Controlling 2-Wire Transmitters with Externally Powered Sources

2-Wire 4-20mA – Input Isolated Sensor Transmitter

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XTR117 wrong output current