4-20mA sensor to a microcontroller
The output from the sensor is a current source so you only need to make sure you can produce the right voltage for your ADC. In your case, 150 Ohms should be your sense resistor to give you 3 V full scale. A 6 V supply on the current source should be able to get that done. As pointed out in Arsenal's answer, in order to get the 6V minimum on the sensor, you'll need at least 9 Volt power supply when at full scale. If you have a long wire, or lot's of connectors in the run, you should use a higher voltage to insure that the sensor has at least the minimum voltage applied.



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