Signal chain solution for 4 to 20-mA HART enabled field instrument applications

Analog Devices Inc. introduced the CN0267 demonstration circuit for a loop powered HART® (Highway Addressable Remote Transducer) enabled smart transmitter, for industrial applications that need to operate within a set 3.5-mA power budget. This field instrument circuit demonstrates a complete low power, high precision signal chain solution with minimum area overhead, which has been tested and verified by ADI as part of their Circuits from the Lab™ reference circuits’ initiative.

To buy and evaluate this circuit and download the application note and watch the video: http://www.analog.com/CN0267
Connect with engineers and ADI product experts on EngineerZone™, an online technical support community: http://ez.analog.com/community/circuits_from_the_lab
Find application notes and technical articles about field instrument solutions from ADI: http://processcontrol.analog.com/en/field-instruments-smart-transmitters/segment/pcia.html

This circuit has been compliance tested, verified and registered as an approved HART solution by the HART Communication Foundation. This ensures that systems designed with these ADI devices will adhere to HART protocol requirements and that DEMO-AD5700D2Z is a proven, tested solution.

Combining the lowest power components in their class, this solution enables system engineers to support increased system functionality including the communications of diagnostics and additional measurement or calibration data. The 7-cm by 2.3-cm CN0267 PCB demonstrates a direct sensor interface, microprocessor and two-way HART communication over a 4- 20-mA loop.

About the CN0267 Circuit Design

CN0267 combines three of ADI’s lowest power, high performance components, optimized for field instrument designs;

The ADuCM360, a low power, fully integrated, 3.9-kSPS, 24-bit data acquisition system-on-a-chip incorporating dual, sigma-delta A/D converters, a 32-bit ARM CortexTM M3 MCU, and flash/EE memory. Using less than 1-mA of operating current it delivers more processing-per-mW of power than any other analog microcontroller within its class.

The AD5421, is a complete, loop powered, 16-bit, 4-mA to 20-mA DAC that incorporates a programmable voltage regulator used to power the demonstration board. The AD5421 consumes less than 300-µA of quiescent current providing a 50 percent power saving and a 55 percent footprint saving over competing offerings.

The AD5700 is a complete HART modem IC, consuming 38 percent less power and supporting a greater than 75 percent saving in board area over alternative products.