Flexible 4mA to 20mA loop-powered pressure sensor transmitter with integrated voltage or current driver

　　Advantages and features

4-20mA loop powered transmitter

Voltage or current drive

Optimized pressure sensor

Products used in this circuit

AD8226

ADA4091-2

ADR02

　　application:

Field instrumentation and smart transmitters

　　Circuit functions and advantages

The circuit shown in Figure 1 is a robust and flexible loop-powered current transducer that converts the differential voltage output of a pressure sensor into a 4 mA to 20 mA current output. The design is optimized for a variety of bridge-type voltage or current-driven pressure sensors, using only four active components and achieving a total unadjusted error of less than 1%. The loop supply voltage range is 12V to 36V. The inputs of this circuit are ESD protected and provide voltage protection above the supply rails, making it ideal for industrial applications.

Figure 1. Robust loop-powered pressure sensor signal conditioning circuit with 4 mA to 20 mA output (shown in sensor voltage drive mode), schematic: all connections and decoupling not shown