AD7731BR

Overview

The AD7731BR is a complete analog front-end for process control applications, featuring a 24-bit sigma-delta ADC architecture. It includes a proprietary programmable gain front end with three buffered differential inputs configurable as five pseudo-differential inputs. The device operates from a single +5 V supply and supports seven unipolar and bipolar input ranges from ±20 mV to ±1.28 V. It achieves 16 bits of peak-to-peak resolution at an 800 Hz output rate, with programmable rates up to 6.4 kHz. The part offers self-calibration, offset drift less than 5 nV/°C, and gain drift less than 2 ppm/°C.

Feature Summary

• Features a programmable gain front end accepting low-level signals directly from transducers.
• Includes a sigma-delta modulator and a low-pass programmable digital filter for adjustable cutoff and settling time.
• Provides internal self-calibration and system calibration options to minimize drift errors.
• Supports FASTStep mode for rapid channel sequencing with fast settling times.

Applications

• Process Control
• PLCs/DCS
• Industrial Instrumentation

Procurement Notes

Verify the specific package type required, as the AD7731 series is available in 24-lead plastic DIP, SOIC, and TSSOP configurations. Confirm RoHS compliance status based on the ordering suffix (Z). Ensure the selected variant matches the required temperature range and interface compatibility before procurement.

Selection Notes

Select the AD7731BR when a 24-lead SOIC package is required for surface-mount assembly. Consider alternative packages like the AD7731BN for through-hole or AD7731BRU for TSSOP if space constraints differ. Evaluate the need for chopped mode operation to further reduce low-frequency noise and drift in precision measurement applications.

Part Context

The AD7731BR belongs to the Analog Devices AD7731 family of high-precision data converters. This series is designed specifically for industrial process control environments requiring high accuracy and stability. The BR suffix indicates the 24-lead SOIC_W package option within this product line.

Replacement Considerations

Direct pin-compatible replacements include other variants within the AD7731 family such as the AD7731BRZ (RoHS compliant) or different package types like the AD7731BRU. Verify that any substitute maintains the same 24-bit resolution and serial interface compatibility.

FAQ

Can the AD7731BR operate with a microcontroller using only three wires?

Yes, the serial interface can be configured for three-wire operation, making it compatible with standard microcontrollers and DSPs.

What is the maximum output update rate of the AD7731BR?

The device features programmable output rates up to 6.4 kHz.

How does the AD7731BR handle transducer burnout detection?

It incorporates two 100nA burnout currents that allow the user to easily detect if a transducer has burnt out or gone open-circuit.