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Analog Devices has unveiled a 16-bit digital-to-analogue converter (DAC) with onboard power management circuitry designed for loop-powered smart transmitter applications used in industrial equipment.

The AD5421 DAC is said to drive system efficiency by reducing total component count and internal power consumption to allow greater functionality at the remote site.

Smart transmitters are intelligent microprocessor-based field instruments that monitor process control variables, including temperature, mass flow rate, and pressure.

They are typically located in hazardous or remote areas and enable two-way communication via the 4-to-20mA analogue loop by using additional communication protocols.

Power consumption is a primary consideration when selecting electronic circuitry for smart transmitter designs because these field instruments must be powered directly from the 4-to-20mA loop due to their location.

Analog Devices’ AD5421 is a complete, loop-powered, digital to 4-to-20mA transmitter that is claimed to consume 50 per cent less power and offers a 55 per cent footprint saving over competing offers.

Incorporating programmable voltage regulation circuitry, the AD5421 generates the low-voltage supply required to power the peripheral components within the smart transmitter.

By conserving the system power budget, the AD5421 DAC enables systems engineers to select more accurate, higher-power sensor electronics or include supplementary functionality, such as extra communication protocols to enhance network connectivity and display screens to improve system interfacing.

The DAC provides on-chip diagnostics that increase uptime of process control systems located in large plants, such as oil refineries.

The hard linearity and low-drift performance offered by the AD5421 DAC eliminate the need for multiple, costly calibration routines required by traditional discrete solutions to obtain high-end system performance specifications.

The AD5421 includes a voltage regulator, which is commonly used to power itself and other devices in the smart transmitter.

The regulator provides a programmable 1.8V to 12V output voltage.

The device also contains precision 1.25V and 2.5V references, eliminating the need for a discrete regulator and voltage reference.

Consuming 250uA of quiescent current, the AD5421 offers 0.05 per cent maximum total unadjusted error and 5ppm drift performance.

The AD5421 can be used with standard Hart protocol circuitry and offers Namur-compliant output ranges.

The device is specified over the extended industrial temperature range of -40C to +105C and incorporates a standard serial peripheral interface (SPI) compatible interface.

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