AD7781BRUZ-REEL

Overview

The AD7781BRUZ-REEL is a 20-bit, pin-programmable, low-power Sigma-Delta analog-to-digital converter (ADC) manufactured by Analog Devices Inc. It integrates a precision programmable gain amplifier (PGA), an internal clock oscillator, and a bridge power-down switch within a single package. The device operates on a supply voltage ranging from 2.7 V to 5.25 V and supports update rates of 10 Hz or 16.7 Hz. It features a read-only 2-wire serial interface compatible with SPI standards. The component is housed in a 16-lead TSSOP package and is designed for applications requiring high resolution and minimal power consumption.

Feature Summary

• Pin-programmable filter response allows selection between fast settling and high rejection modes.
• Integrated programmable gain amplifier provides selectable gains of 1 or 128.
• On-chip bridge power-down switch enables significant current reduction in battery-operated systems.
• Internal clock oscillator eliminates the need for external timing components.

Applications

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

Procurement Notes

Verify that the ordering suffix matches the required package type and tape-and-reel specifications. Confirm the grade (B or C) aligns with noise performance requirements. Ensure the supplier source is authorized to guarantee component authenticity and traceability. Check RoHS compliance status against specific regional regulatory needs.

Selection Notes

Select this component when a complete front-end solution for bridge sensors is required without external amplifiers. Consider the 16-lead TSSOP package for surface-mount assembly constraints. Evaluate the 10 Hz versus 16.7 Hz update rate based on whether mechanical vibration rejection or faster settling time is prioritized. Verify that the differential input range accommodates the sensor's output relative to the chosen gain setting.

Part Context

The AD7781 belongs to a family of low-power, high-resolution ADCs designed specifically for bridge sensor interfaces. It replaces discrete solutions involving separate amplifiers and converters. The BRUZ suffix indicates the 16-lead TSSOP package variant. This part is distinct from higher-channel or different-resolution counterparts in the same product line.

Replacement Considerations

Public confirmed substitute part numbers are not available in the provided documentation. Direct replacements should be evaluated based on pin compatibility, resolution, and package dimensions.

FAQ

How is the gain of the AD7781 configured?

The gain is set via the dedicated GAIN pin. A logic low sets the gain to 128, while a logic high sets the gain to 1.

What is the function of the BPDSW pin?

The BPDSW pin controls an internal bridge power-down switch. When PDRST is high, the switch closes to excite the sensor; when PDRST is low, the switch opens to minimize current consumption.

Does the AD7781 require an external clock?

No, the AD7781 includes an internal clock oscillator, eliminating the need for external timing components.