AD7731BRZ

Overview

The AD7731BRZ is a 24-bit Sigma-Delta Analog-to-Digital Converter (ADC) designed for process control applications. It features a complete analog front-end with three buffered differential programmable gain inputs, configurable as five pseudo-differential channels. The device operates from a single +5 V analog supply and accepts digital logic voltages between 2.7 V and 5.25 V. Key electrical parameters include a maximum integral nonlinearity of 15 ppm of full-scale range, an offset drift of less than 5 nV/°C, and a gain drift of less than 2 ppm/°C. It supports output data rates up to 6.4 kS/s and achieves 16 bits of peak-to-peak resolution at an 800 Hz update rate. The component is housed in a 24-lead SOIC package.

Feature Summary

• Integrates a proprietary programmable gain front end capable of accepting low-level signals directly from transducers without external amplification.
• Utilizes a Sigma-Delta architecture with a programmable digital filter that allows adjustment of cutoff frequency, output rate, and settling time.
• Includes built-in self-calibration and system calibration options to minimize offset and gain errors over temperature and time.
• Features a serial interface compatible with microcontrollers and DSPs, supporting three-wire operation.

Applications

• Process Control Systems
• Programmable Logic Controllers (PLCs)
• Distributed Control Systems (DCS)
• Industrial Instrumentation

Procurement Notes

Verify the specific ordering suffix to confirm the package type and RoHS compliance status. The 'BRZ' designation indicates a lead-free 24-lead SOIC package compliant with current environmental directives. Ensure the procurement documentation matches the required temperature range and pin configuration for your specific board layout.

Selection Notes

Select this component when high precision and low drift are required for multi-channel signal acquisition. Consider the available input ranges, which span from ±20 mV to ±1.28 V, to match your sensor output levels. Evaluate the trade-off between output data rate and noise performance, as higher speeds reduce effective resolution. Verify compatibility with your system's digital logic voltage levels.

Part Context

The AD7731 belongs to Analog Devices' family of high-resolution Sigma-Delta ADCs tailored for industrial environments. It serves as a direct replacement for older discrete amplifier and ADC solutions in process control loops. The device consolidates buffering, amplification, filtering, and conversion into a single integrated circuit, simplifying schematic design and reducing board space requirements.

Replacement Considerations

Direct pin-compatible alternatives within the same series include the AD7731BN (PDIP package) and AD7731BRU (TSSOP package). When substituting, verify that the thermal characteristics and physical dimensions of the alternative package meet your enclosure constraints. Electrical specifications remain consistent across these package variants.