AFE781H1RRUT

Analog Front End (AFE) Overview

The AFE781H1 is a 14-bit low-power digital-to-analog converter (DAC) with an integrated HART modem, voltage reference, and diagnostic ADC. It operates from a single supply of 1.71 V to 5.5 V, consuming a typical quiescent current of 180 µA. The device features a 12-bit, 3.84-kSPS diagnostic ADC for internal health checks and includes a 1.25-V reference with 10 ppm/°C drift. It supports SPI and UART interfaces up to 12.5 MHz and functions within a temperature range of –55°C to +125°C.

Analog Front End (AFE) Feature Summary

• 14-bit monotonic DAC with 4-LSB INL and 0.07% FSR TUE over temperature
• Integrated HART-compliant FSK modem for process communication
• 12-bit diagnostic ADC for automatic self-health monitoring
• Low power consumption: 180 µA typical quiescent current

Analog Front End (AFE) Applications

• 2-wire, 4-mA to 20-mA loop-powered transmitters
• Process control and industrial automation systems
• Smart transmitters requiring HART protocol support

Analog Front End (AFE) Procurement Notes

Verify the package marking code RRU corresponds to the 24-pin UQFN (4.00 mm × 4.00 mm). Confirm that external voltage-to-current conversion components are included in the design, as the AFE781H1 provides only the analog front-end signals. Ensure the PCB layout adheres to the thermal resistance specifications provided in the datasheet.

Analog Front End (AFE) Selection Notes

Select the AFE781H1 when a 14-bit resolution is sufficient for the application, offering lower cost compared to the 16-bit AFE881H1. Verify that the required output voltage range (0.15 V to 1.25 V or 0.3 V to 2.5 V) aligns with the system's PVDD configuration. Check if the integrated diagnostic ADC meets the specific fault detection requirements for functional safety.

Analog Front End (AFE) Part Context

The AFE781H1 belongs to the AFEx81H1 family, designed specifically for HART-enabled sensor-transmitter applications. It integrates most components needed for 4-mA to 20-mA loop-powered designs, including the DAC, modem, and reference. The device complements the higher-resolution AFE881H1 by providing a cost-effective solution for applications not requiring 16-bit precision.

Analog Front End (AFE) Replacement Considerations

The AFE881H1 is the direct 16-bit counterpart in the same family. It shares the same pinout, package, and interface protocols but offers higher resolution and slightly different error specifications. No other cross-model replacements are documented.