Circuit Note CN-0295 Devices Connected/Referenced Wide Supply Range, Rail-to-Rail AD8226 Circuits from the Lab reference circuits are engineered and Output Instrumentation Amplifier tested for quick and easy system integration to help solve todays Ultracompact, Precision 5.0 V Voltage analog, mixed-signal, and RF design challenges. For more ADR02 Reference information and/or support, visit www.analog.com/CN0295. Precision Micropower, OVP, RRIO ADA4091-4 Operational Amplifier Flexible, 4 mA-to-20 mA Pressure Sensor Transmitter with Voltage or Current Drive The circuit is optimized for a wide variety of bridge-based voltage EVALUATION AND DESIGN SUPPORT or current driven pressure sensors, utilizes only five active Circuit Evaluation Boards devices, and has a total unadjusted error of less than 1%. The CN0295 Evaluation Board (EVAL-CN0295-EB1Z) power supply voltage can range from 7 V to 36 V depending on Design and Integration Files the component and sensor driver configuration. Schematics, Layout Files, Bill of Materials The input of the circuit is protected for ESD and voltages beyond CIRCUIT FUNCTION AND BENEFITS the supply rail, making it ideal for industrial applications. The circuit shown in Figure 1is a flexible current transmitter that converts the differential voltage output from a pressure sensor to a 4 mA-to-20 mA current output. V +5V CC +V 1/4 CC ADA4091-4 +V +V REF CC I U2A 15 V ADR02 +V DRIVE CC 4mA, R15 +5V 100 20mA J3-3 +V SS G = 16.06 R R BRIDGE BRIDGE R5 V R1 2k CC 1nF R12 J3-2 4.02k 1k +V CC Q2 V 10nF V 1/4 IN U1 OUT R3 R6 ADA4091-4 AD8226 R R R2 3.28k 10k BRIDGE BRIDGE 100 U2D P1-1 4.02k Q1 J1-1 1/4 J3-1 J3-4 ADA4091-4 1nF REF J1-2 V = 0mV 100mV IN U2C Q1: BC847C, 215 R14 Q2: SI2319DS-T1-E3 +V REF 499 +V CC R7 P1-2 11.5k 0.4V, 2.0V I R13 0.4V 13 PCB GROUND 1k R8 0.4mA, 1k 1/4 2.0mA ADA4091-4 U2B Figure 1. Pressure Sensor Signal Conditioning Circuit with 4 mA-to-20 mA Output (Shown in Sensor Voltage Drive Mode) (Simplified Schematic: All Connections and Decoupling Not Shown) Rev.0 Circuits from the Lab circuits from Analog Devices have been designed and built by Analog Devices engineers. Standard engineering practices have been employed in the design and construction of each circuit, and their function and performance have been tested and verified in a lab environment at room temperature. However, you are solely responsible for testing the circuit and determining its One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. suitability and applicability for your use and application. Accordingly, in no event shall Analog Devices Tel: 781.329.4700 www.analog.com be liable for direct, indirect, special, incidental, consequential or punitive damages due to any cause Fax: 781.461.3113 2013 Analog Devices, Inc. All rights reserved. whatsoever connected to the use of any Circuits from the Lab circuits. (Continued on last page) 11610-001CN-0295 Circuit Note configuration for the voltage drive with S1 in the position CIRCUIT DESCRIPTION closest to the identifying marking (see complete circuit layouts The design provides a complete solution for the 4 mA-to-20 mA and schematics in the CN0295 design support package: transmitter for pressure sensor measurements. The circuit has