GENERAL DESCRIPTION

The AD5421 is a complete, loop-powered, 4 mA to 20 mA digital-to-analog converter (DAC) designed to meet the needs of smart transmitter manufacturers in the industrial control industry. The DAC provides a high precision, fully integrated, low cost solution in compact TSSOP and LFCSP packages.

The AD5421 includes a regulated voltage output that is used to power itself and other devices in the transmitter. This regulator provides a regulated 1.8 V to 12 V output voltage. The AD5421 also contains 1.22 V and 2.5 V references, thus eliminating the need for a discrete regulator and voltage reference.

FEATURES

16-bit resolution and monotonicity

Pin selectable NAMUR-compliant ranges

4 mA to 20 mA

3.8 mA to 21 mA

3.2 mA to 24 mA

NAMUR-compliant alarm currents

Downscale alarm current = 3.2 mA

Upscale alarm current = 22.8 mA/24 mA

Total unadjusted error (TUE): 0.05 maximum

INL error: 0.0035 FSR maximum

Output TC: 3 ppm/°C typical

Quiescent current: 300 µA maximum

Flexible SPI-compatible serial digital interface

with Schmitt triggered inputs

On-chip fault alerts via FAULT pin or alarm current

Automatic readback of fault register on each write cycle

Slew rate control function

Gain and offset adjust registers

On-chip reference TC: 4 ppm/°C maximum

Selectable regulated voltage output

Loop voltage range: 5.5 V to 52 V

Temperature range: −40°C to +105°C

TSSOP and LFCSP packages

APPLICATIONS

Industrial process control

4 mA to 20 mA loop-powered transmitters

Smart transmitters

HART network connectivity