Circuit functions and advantages
The circuit shown in Figure 1 is a robust and flexible loop powered current transmitter that converts the differential voltage output of the pressure sensor to a 4 mA to 20 mA current output.
The design is optimized for various bridge voltage or current driven pressure sensors. Only four active devices are used, and the total non adjustable error is less than 1%. The loop supply voltage range is 12 V to 36 v.
The input of the circuit has ESD protection function and can provide voltage protection higher than the power supply rail. It is an ideal choice for industrial applications.
Figure 1. Robust loop powered pressure sensor signal conditioning circuit with 4 mA to 20 mA output
(shown as sensor voltage drive mode), schematic diagram: not all connections and decoupling are shown