AD7731BN

Overview

The AD7731BN 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 on a single +5 V supply (AVDD) and a digital supply of +2.7 V to +5.25 V (DVDD). It provides 16 bits peak-to-peak resolution at an 800 Hz output rate, with programmable rates up to 6.4 kHz. The part includes three buffered differential inputs configurable as five pseudo-differential inputs, self-calibration options, and an offset drift of less than 5 nV/°C.

Feature Summary

• Features a programmable gain front end that accommodates low-level signals directly from transducers without external buffering.
• Integrates a Sigma-Delta architecture with a programmable digital filter allowing adjustment of cutoff frequency, output rate, and settling time.
• Includes internal self-calibration and system calibration capabilities to minimize offset and gain errors over temperature and time.
• Supports FASTStep mode for rapid channel sequencing with fast settling times during multiplexer switching.

Applications

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

Procurement Notes

Verify the specific package type and RoHS compliance status when ordering, as the 'BN' suffix denotes a non-RoHS compliant 24-lead PDIP package. Confirm availability through authorized distributors, as this component may be subject to limited supply or end-of-life considerations depending on current inventory levels.

Selection Notes

Select the AD7731BN for applications requiring high-resolution data acquisition with integrated signal conditioning. Ensure the design supports the required AVDD (+5 V) and DVDD (+2.7 V to +5.25 V) power supplies. Consider the 24-lead PDIP package constraints for PCB layout if thermal dissipation or pin count limits are factors in the enclosure design.

Part Context

The AD7731 belongs to Analog Devices' family of precision Sigma-Delta analog-to-digital converters designed for industrial environments. It serves as a monolithic solution for low-frequency, high-accuracy measurements, eliminating the need for separate amplifiers and filters in traditional signal chains.

Replacement Considerations

The AD7731BRZ is a RoHS-compliant alternative available in a 24-lead SOIC package. For direct pin-compatible replacement in the same package style, verify availability of other variants within the AD7731 series that match the required lead-free specifications.