AFE781H1RRUR

Analog Front End (AFE) Overview

The AFE781H1RRUR is a 14-bit low-power digital-to-analog converter (DAC) with an integrated HART modem, voltage reference, and diagnostic ADC. Designed for 4-mA to 20-mA loop-powered applications, it features a quiescent current of 180 µA (typical). The device includes a 12-bit, 3.84-kSPS diagnostic ADC and an internal 1.25-V reference with 10 ppm/°C drift. It supports SPI and UART interfaces and operates from PVDD supplies between 1.71 V and 5.5 V. The component is housed in a 24-pin UQFN package and functions across 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
• Integrated HART-compliant physical layer modem
• 12-bit diagnostic ADC operating at 3.84 kSPS
• Internal 1.25-V voltage reference with 10 ppm/°C drift

Analog Front End (AFE) Applications

• 2-wire, 4-mA to 20-mA loop-powered transmitters
• Process control systems
• Industrial automation equipment
• Smart transmitters

Analog Front End (AFE) Procurement Notes

Verify the specific ordering suffix RRUR corresponds to the 24-pin UQFN package configuration. Confirm that external voltage-to-current conversion circuitry is included in the design, as the device requires external components to accommodate intrinsic and functional safety concerns for loop-powered implementations.

Analog Front End (AFE) Selection Notes

Select this model when a 14-bit resolution is sufficient for the application, distinguishing it from the 16-bit AFE881H1 variant. Ensure the system design accommodates the required external power regulation and current conversion stages necessary for 4-mA to 20-mA loop operation.

Analog Front End (AFE) Part Context

This component belongs to the AFEx81H1 family, which also includes the 16-bit AFE881H1. Both devices share identical integration levels, including the HART modem and diagnostic capabilities, but differ in DAC resolution. The AFE781H1 provides a cost-effective solution for applications where 14-bit precision meets accuracy requirements.

Analog Front End (AFE) Replacement Considerations

The AFE881H1 serves as a direct pin-compatible alternative offering 16-bit resolution instead of 14-bit. No other verified public substitutes are identified in the documentation.

Analog Front End (AFE) FAQ

What is the maximum serial clock frequency supported by the SPI interface?

The SPI interface supports data transfer rates with a serial clock frequency up to 12.5 MHz.

How does the device handle fault detection?

The device utilizes CRC bit error checking, a windowed watchdog timer, and the diagnostic ADC to detect faults. Upon detection, it can issue an interrupt or enter a fail-safe state corresponding to standard NAMUR values.

What is the input voltage range for the diagnostic ADC?

When PVDD equals VDD (1.71 V to 1.89 V), the input range is 0 V to 1.25 V. When PVDD exceeds 2.7 V, the input range extends to 0 V to 2.5 V.