Convert 1 to 5V signal to 4- to 20-mA output

摘要

Despite the long-predicted demise of the 4- to 20-Ma current loop, this analog interface is still the most common method of connecting current-loop sources to a sensing circuit. This interface requires the conversion of a voltage signal-typically, 1 to 5V-to a 4- to 20-Ma output. Stringent accuracy requirements dictate the use of either expensive precision resistors or a trimming potentiometer to calibrate out the initial error of less precise devices to meet the design goals.