AD7781BRZ-REEL

Overview

The AD7781BRZ-REEL is a 20-bit, pin-programmable, low-power Sigma-Delta analog-to-digital converter (ADC) manufactured by Analog Devices Inc. It features an integrated programmable gain amplifier (PGA) with selectable gains of 1 or 128, and an internal clock oscillator. The device operates on a single power supply ranging from 2.7 V to 5.25 V for both analog (AVDD) and digital (DVDD) domains. It offers two update rates: 16.7 Hz with a 120 ms settling time, and 10 Hz with a 300 ms settling time. The component provides simultaneous 50 Hz/60 Hz rejection and includes a bridge power-down switch. It utilizes a read-only SPI-compatible serial interface and is housed in a 14-lead narrow body SOIC package.

Feature Summary

• Pin-programmable filter response and in-amp gain selection
• Integrated low noise programmable gain amplifier
• Internal clock oscillator and bridge power-down switch
• Simultaneous 50 Hz/60 Hz line frequency rejection

Applications

• Weigh scales
• Pressure measurement
• Industrial process control
• Portable instrumentation

Procurement Notes

Verify the specific grade (B or C) required for your application, as RMS noise and peak-to-peak resolution specifications vary between grades. Confirm that the 14-lead SOIC package aligns with your PCB footprint requirements. Ensure the external reference voltage source has low output impedance to prevent gain errors due to the unbuffered reference input architecture.

Selection Notes

Select the AD7781BRZ-REEL when a complete front-end solution for bridge sensors is needed without external amplifiers. Choose the 16.7 Hz update rate for faster settling times or the 10 Hz rate for superior stop-band attenuation against mechanical vibrations. Verify that the differential input range matches the sensor output relative to the chosen PGA gain setting.

Part Context

This component belongs to the AD7781 family of precision ADCs designed specifically for low-frequency, high-resolution measurements. It serves as a dedicated signal chain for resistive bridge sensors, integrating modulation, filtering, and amplification into a single monolithic device to simplify system design and reduce component count.

Replacement Considerations

Public confirmed substitute part numbers are not available.