XTR116: How to supply 5-V sensors with more current from 2-wire 4-20mA current loop using XTR116

Uroschanit Yodprasit

Prodigy 10 points

Part Number: XTR116
Other Parts Discussed in Thread: XTR111, XTR117, XTR115

Tool/software:

Hello,

I am tying to use XTR116 for my 4-20mA transmitter project.

In this project, the sensor is 5-V sensor (together with a microcontroller) and they both draw about 300 mA.

I am planning to use XTR116, but the on-chip 5V regulator cannot supply such high current.

In addition, I would like to supply the whole system (i.e., sensor + microcontroller + 4-20mA transmitter) using only from the 2-wire 4-20mA current loop, without adding any extra DC supply for the sensor.

How could I realize this system ?

I have done some research, but it seems that there is no exact solution ...

Best regards and thank you very much,

8 months ago

0 Clemens Ladisch 8 months ago

Guru 294230 points

The current draw is the signal. So when you power the sensor from the current loop, then the maximum current draw must be less than 4 mA, otherwise you would not be able to transmit a signal of 4 mA.

If you want to draw 300 mA, then you need a separate power supply, i.e., a 3-wire loop, with a 3-wire transmitter like the XTR111.

0 Raymond Zhang1 8 months ago

TI__Guru 60051 points

Hi Yodpra,

Uroschanit Yodprasit said:
In this project, the sensor is 5-V sensor (together with a microcontroller) and they both draw about 300 mA.

The 5V sensor with 300mA has impedance about 5V/0.3 = 16.7Ω. As Clemens indicated, you may have to use XTR111, 3-wire current loop transmitter for the application.

For 2-wire current loop transmitter, you have 5V sensor + MCU (micro power CMU) has to consume less than 3.7mA in order to use it. Please take a look at the following application materials, including videos.

https://e2e.ti.com/support/amplifiers-group/amplifiers/f/amplifiers-forum/945173/faq-what-is-a-2-wire-4-20ma-current-transmitter?tisearch=e2e-sitesearch&keymatch=%25252525252525255BFAQ%25252525252525255D%252525252525252520xtr117#

You may use digital isolator to interface between sensor and XTR115/XTR116/XTR117 2-wire current loop transmitter, but the digital isolator is sending PWM signal and the input is the average of PWM signal via RC LP filter. For high accuracy application, this topology may not be suitable. In that case, XTR111 3-wire will be the best option.

Please let me know how you'd like to proceed.

Best,

Raymond

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XTR116: How to supply 5-V sensors with more current from 2-wire 4-20mA current loop using XTR116