Precision DACs for industrial automation systems

31 October 2007 Analogue, Mixed Signal, LSI

Analog Devices has introduced new precision digital-to-analog converters (DACs) that are designed to improve the reliability of industrial process control applications in harsh factory environments, including those operating under extreme temperatures or high compliance voltages. The offering includes four 12-bit to 16-bit single-channel DACs that integrate user-programmable current source and voltage output, making them suited for factory process control, distributed control and smart transmitter systems.

The new products, which include the AD5422, AD5420, AD5412 and AD5410, leverage the technological advancements enabled by Analog Devices' iCMOS industrial process technology, allowing them to achieve the high voltages needed by industrial applications. The AD5422 single-channel 16-bit DAC operates from a single 12 V to 48 V supply, or dual ±12 V to ±24 V supplies. The output configuration is software selectable from options of 5 V, 10 V, ±5 V and ±10 V in voltage mode and 4-20 mA, 0-20 mA, and 0-24 mA in current mode. All output spans include an additional over-range setting.

The AD5422 achieves an accuracy level of 0,1% TUE (total unadjusted error) while operating in voltage or current mode and includes a precision 5 ppm/°C internal reference. Internal fault detection circuitry provides hardware and software indication of line faults, such as open- or short-circuits in cable wiring or remotely located loads. The device also integrates an over-temperature indicator. To sense output voltage, it includes a buffered voltage output with force and sense capability that can compensate for series protection resistors and field-wiring resistance. The on-chip programmable precision output amplifier allows rail-to-rail output swing to be achieved. Analog outputs can drive capacitive loads up to 1 μF and inductive loads up to 1 H.

The AD5412 is a pin-compatible single-channel 12-bit current source and voltage output DAC. The AD5420 (16-bit) and AD5410 (12-bit) operate in current source mode only. With a single 12 V to 60 V supply, their output configuration is software selectable from 4-20 mA, 0-20 mA and 0-24 mA options.

The new DACs incorporate a 30 MHz serial peripheral interface (SPI), power-on reset and hardware CLR and CLR-select functionality for output control. Each device is fully specified over the industrial temperature range.

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