AD7731BRZ-REEL7

Overview

The AD7731BRZ-REEL7 is a complete analog front-end for process control applications, featuring a 24-bit sigma-delta ADC with a proprietary programmable gain front end. It accepts seven unipolar and seven bipolar input ranges from ±20 mV to ±1.28 V directly from transducers. The device operates from a single +5 V analog supply and a 2.7 V to 5.25 V digital supply. It provides three buffered differential inputs configurable as five pseudo-differential inputs, achieving 16 bits of peak-to-peak resolution at an 800 Hz output rate. Programmable output rates extend up to 6.4 kHz, with a channel switching settling time of 1 ms.

Feature Summary

• Features a programmable gain front end that accommodates low-level signals directly from transducers without external amplification.
• Includes a two-stage digital filter system allowing adjustment of cutoff frequency, output update rate, and settling time.
• Supports self-calibration and system calibration options to minimize offset drift and gain errors over temperature and time.
• Integrates burnout currents to facilitate the detection of open-circuit transducer faults.

Applications

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

Procurement Notes

Verify the specific REEL7 suffix indicates tape and reel packaging when sourcing this component. Confirm the B version designation corresponds to the industrial temperature range of -40°C to +85°C. Ensure the ordering information matches the required RoHS compliance status indicated by the Z suffix in the part number.

Selection Notes

Select this component for applications requiring high-resolution data acquisition with integrated signal conditioning. Consider the available input ranges and the need for differential versus pseudo-differential configurations. Evaluate the power supply requirements, noting the separate analog and digital voltage specifications. Assess the interface compatibility with microcontrollers or DSPs using the serial communication protocol.

Part Context

The AD7731 belongs to Analog Devices' family of low-noise, high-throughput 24-bit sigma-delta analog-to-digital converters. This series is designed specifically for process control environments where precision and stability are critical. The BRZ-REEL7 variant denotes the surface-mount SOIC package form factor within this product line.

Replacement Considerations

Consult official documentation for direct pin-compatible substitutes within the AD773x family. Verify electrical parameters such as input ranges and sampling rates against alternative models before implementation.

FAQ

How many analog input channels does the AD7731 support?

The device supports three fully differential inputs which can be configured as five pseudo-differential inputs using the internal multiplexer.

What is the maximum output update rate of the ADC?

The programmable output rates allow for updates up to 6.4 kHz depending on the selected filter settings.

Can the AIN3 and AIN4 pins function as digital outputs?

Yes, when the DEN bit in the Mode Register is set, these pins can be reconfigured as two programmable digital output lines.