Combination 0-10V / 4-20mA Output Circuit

[Evan.Cornell]

A recent project had a requirement for a 0-10V control signal output port. I had implemented with MCU PWM pin, filtered and gained appropriately via non-inverting op-amp.

Then, as is wont, the requirements changed such that the control signal output port had to support either 0-10V voltage output or a 4-20mA current loop output, on the same two-pin connector. The current loop output is supplying the loop voltage, which is backwards from how current loop transmitters usually work.

Anyone have any clever ideas on a switchable circuit that can take a 0/3.3V PWM signal in and produce either 0-10V or 4-20mA output signal? Primary consideration is low-cost.

I had seen XTR305 which might've fit the bill, but it seems to want bipolar power rails, which would inflate the cost too much.

[S. Petrukhin]

Look at the datasheet of this optocoupler-the transmitter and receiver 4..20 are implemented there.
https://lcsc.com/product-detail/Optocouplers_AVAGO-Broadcom_HCNR200-500E_AVAGO-Broadcom-Avago-HCNR200-500E_C23785.html

[S. Petrukhin]

And look tis chip: https://lcsc.com/product-detail/Sensor-Interface-ICs_Texas-Instruments-XTR116UA-2K5_C368611.html

[S. Petrukhin]

I had seen XTR305 which might've fit the bill, but it seems to want bipolar power rails, which would inflate the cost too much.

it has a unipolar power supply. Due to the specifics of Gnd, it is named V - and using for +/-10V output.