Bridge Measurement - 0 to 20mA Current Output Circuit

RTD is a temperature measuring resistor, and the thermocouple ruler is used as cold junction compensation. They are
driven by the lrnA current source output by XTR101 as a constant current. When the RTD senses the temperature change, it causes the voltage between the ④ and ③ pins to change. This As the input signal
of XTR101 , XTR101 converts it into a 4~20mA current output. The circuit shown in Figure 10-29 can convert the measurement signal of the bridge sensor into an O~20mA current output.     XTR101 converts the measurement signal of the bridge sensor into a 4~20mA current output, and the output current forms a voltage on Rj ; the operational amplifier OPA27 is connected as a voltage-to-current converter, and its inverting input (one) terminal and the output terminal are connected to 2 .SV reference voltage source so that the voltage between them is constant 2. 5V. Therefore, the output current     , o=(1 +RI/R2), VR/RZ=1.251-5(mA),     when I=4~20mA, Io=O—20rnA.