Does ADI have the companion chip to the AD420 4-20mA DAC that converts 4-20 into a digital value?
Apologies for the delayed response. The 4-20mA output is intended for industrial process control systems analog signaling where 4mA is the lowest end and 20mA is the highest. There is no recommended companion for the AD420 as the parts accepts voltage as inputs. You may want to convert the 4-20mA to voltage and find and ADC that would accept that range of voltage input. You may want to take a look the ADC portfolio of by clicking here.
Generally the loop goes into a precision 50 ohm resistor, so you get 200 mV to 1V which
goes to a 24 bit ADC.