The AFEx81H1 feature a 16-bit (AFE881H1) or 14‑bit (AFE781H1) string DAC with voltage output buffer. Both devices are capable of operating from supplies as low as 1.71 V at very low power, and are designed for 4-mA to 20-mA, loop-powered applications. The AFEx81H1 have two different DAC output voltage ranges depending on supply voltage, and two other ranges depending on configuration. The DAC has calibration registers for setting gain and offset values for adjusting the DAC outputs. The DAC also has different output slewing modes that allow for a programmable linear slew and a sinusoidal shaped output slew.

The AFEx81H1 also feature a 12‑bit SAR ADC that can be multiplexed to measure different inputs, including external nodes and internal nodes for diagnostic measurements on the device. The ADC is capable of making direct-mode measurements with on-demand conversions or auto-mode measurements through continuous conversions using a channel sequencer with a multiplexer. The devices have optional alarm configurations with fault detection and alarm actions.

Device communication and programming are done through an SPI, SPI plus a UART interface, or through the UART break mode (UBM). With the SPI, a cyclic redundancy check (CRC) is implemented by default, which can be disabled. Additionally, communications can be monitored with a watchdog timer (WDT) that alerts the user if the device becomes unresponsive to periodic communication.

For the field transmitter, a HART interface is created through modulation and demodulation using the SPI or UART. The demodulation of the input signal is done using the combination of the external and internal band-pass filtering.

The AFEx81H1 feature a 1.25-V, onboard precision voltage reference, and an integrated precision oscillator.

Throughout this data sheet, register and bit names are combined with a period to use the following format: <register_name>.<bit_name>. For example, the CLR bit in the DAC_CFG register is labeled DAC_CFG.CLR.