Hi My question is the following: Does the XTR116UA chip need to be isolated from the external circuitry?
Can I tie the circuit ground to the Iret Pin (3) of the chip?
I will provide a remote Loop Voltage/termination resistor between pin 7 and 4.
I need the XTR116UA to interface to circuitry that will have it's own 5V power supply and GND.
Can I connect the DAC between the XTR116UA Vref (pin 1) and the circuit ground?
See attached diagram.
Thanks,
Hello,
The system will not work as drawn in your current schematic because the IRET pins must be allowed to float up and down as the output current changes as you've guessed. This is covered in part 3 and expanded upon in parts 4 and 5 of the blog series linked below. Many designs use a PWM DAC structure to minimize the number of signals that have to pass through the isolation barrier but if you can find an isolated I2C translator that consumes <2-2.5mA while active then that would work in your system. Just keep in mind that the isolation solution you choose can't consume more than 3.5mA (explained in part 2 of the blog series) or the transmitter won't be able to output the desired 4mA zero-scale level.
