AD7731BNZ

Overview

The AD7731BNZ 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 of peak-to-peak resolution at an 800 Hz output rate, with programmable rates up to 6.4 kHz. The architecture includes three buffered differential inputs configurable as five pseudo-differential inputs, self-calibration capabilities, 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 amplification.
• Incorporates a sigma-delta architecture with a low-pass programmable digital filter allowing adjustment of cutoff frequency and settling time.
• Includes internal self-calibration and system calibration options to minimize offset and gain errors over temperature and time.
• Supports FASTStep mode for rapid channel sequencing with fast settling times during input transitions.

Applications

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

Procurement Notes

Verify the specific B-version suffix against current Analog Devices ordering guides to ensure compliance with the -40°C to +85°C industrial temperature range. Confirm RoHS status via the Z suffix if required by assembly specifications. Cross-reference pinout compatibility with existing PCB layouts due to the 24-lead PDIP package dimensions.

Selection Notes

Select this component when high precision is required for multi-channel process control signals. Ensure the application supports the required 2.7 V to 5.25 V digital supply voltage. Verify that the external clock source matches the specified master clock frequency requirements for the desired output data rate and filter performance.

Part Context

The AD7731 series serves as a dedicated signal chain solution for industrial sensors. The BNZ designation specifically identifies the 24-lead plastic DIP package variant compliant with RoHS directives. This package option facilitates through-hole mounting for robust industrial environments compared to surface-mount alternatives.

Replacement Considerations

The AD7731BRZ offers identical electrical characteristics in a 24-lead SOIC package. The EVAL-AD7731EBZ is the official evaluation board for development purposes. No direct functional substitutes are documented in the provided datasheet.