AD7781BRUZ

Overview

The AD7781BRUZ is a 20-bit, pin-programmable, low-power Sigma-Delta analog-to-digital converter manufactured by Analog Devices Inc. It integrates a precision programmable gain amplifier (PGA) with selectable gains of 1 or 128, an internal clock oscillator, and a bridge power-down switch. The device operates on a single supply voltage ranging from 2.7 V to 5.25 V for both analog and digital domains. It supports two update rates: 16.7 Hz with a 120 ms settling time, and 10 Hz with a 300 ms settling time. The component utilizes a read-only 2-wire serial interface compatible with SPI standards.

Feature Summary

• Pin-programmable filter response allowing selection between fast settling and high rejection modes
• Integrated low-noise programmable gain amplifier supporting gains of 1 or 128
• On-chip bridge power-down switch controlled via the PDRST pin for sensor power management
• Internal clock oscillator eliminates the need for external timing components

Applications

• Weigh scales
• Pressure measurement systems
• Industrial process control instrumentation
• Portable battery-operated instrumentation

Procurement Notes

Verify the specific grade (B or C) required for noise performance specifications before ordering. Confirm that the 16-lead TSSOP package matches the target PCB footprint. Ensure the design accommodates the independent DVDD and AVDD supply requirements as the digital and analog supplies are not internally connected.

Selection Notes

Select this component for applications requiring low power consumption and direct connection to resistive sensors like strain gauges. Choose the B Grade if lower RMS noise is critical at the 10 Hz update rate compared to the C Grade. Verify that the input signal range fits within the ±VREF/gain limits for the selected gain setting.

Part Context

The AD7781 belongs to the AD778x family of low-power, pin-programmable ADCs designed for bridge sensor interfaces. It shares architectural similarities with the AD7780 and AD7783 but offers distinct pin-programmable configuration options for gain and filtering. The BRUZ suffix indicates the commercial temperature range and the 16-lead TSSOP package variant.

Replacement Considerations

Public confirmed substitute part numbers are not available in the provided documentation.