4-20mA output from Arduino Due DAC

Projects General Guidance
1

I need to add 4-20mA (current-regulated) outputs to my Due project. I did a little snooping around and found TI's XTR110 IC which is specifically made for converting voltage to current (e.g. 1-5V to 4-20 mA). Problem is, it's for 5V, and the Due works with 3.3V (max 5/6ths of that for the DAC from the SAM3X datasheet). Couldn't find a similar IC that works with that, so I figured I'd just use an opamp like in the following link: http://www.allaboutcircuits.com/textbook/semiconductors/chpt-8/voltage-to-current-signal-conversion/

Current plan is to get a 741 IC and a voltage inverter IC to provide the needed negative voltage to the op-amp. Instead of 250 ohms for the resistance, it'll be (5/6 * 3.3)/(20 mA) = 137.5 ohms. Is this a solid plan or is there a better route to go? I was really hoping to use something like the XTR110 which seems like it'd be more reliable and accurate than just a single op-amp.

Thank you for your help!

2

Better option single power rail-to-rail:

TS922 or similar

3

No direct experience in this, but reading the datasheet, I think you can use the XTR110.
Just use it in the standard 0-5volt in config.
And adjust the span for 30.3mA with 5volt in.
That will give you 20mA with 3.3volt in.
Leo..

4

Wawa:
No direct experience in this, but reading the datasheet, I think you can use the XTR110.
Just use it in the standard 0-5volt in config.
And adjust the span for 30.3mA with 5volt in.
That will give you 20mA with 3.3volt in.
Leo..

Thanks Wawa, I think you're right after looking further.

5

http://www.analog.com/media/en/technical-documentation/data-sheets/AD421.pdf

6

Thanks Wawa. After poking around on their website, I'm going to use the AD5420. Thanks!!!

7

You can see my simple circuit on Arduino Playground and the complete project on my blog;