AD7730BR

Overview

The AD7730BR is a complete analog front end for weigh-scale and pressure measurement applications, featuring a Sigma-Delta architecture. It provides 24-bit resolution with no missing codes and achieves 230,000 counts peak-to-peak. The device includes two buffered differential programmable gain inputs (PGA) and accepts low-level transducer signals directly. Key electrical parameters include an offset drift of 5 nV/°C, gain drift of 2 ppm/°C, and integral nonlinearity of 18 ppm FSR. It operates from a single +5 V analog supply (AVDD: 4.75 V to 5.25 V) and a digital supply (DVDD: 2.7 V to 5.25 V). Power dissipation is 65 mW in normal mode.

Feature Summary

• 24-bit resolution with 230,000 counts peak-to-peak and <5 nV/°C offset drift
• Two-channel buffered differential PGA with input ranges from ±10 mV to ±80 mV
• On-chip 6-bit DAC for offset/tare removal and AC excitation clock outputs
• Programmable digital filter with FastStep™ mode and line frequency rejection >150 dB

Applications

• Weigh scales
• Pressure measurement

Procurement Notes

Verify the suffix 'BR' indicates the industrial temperature range (-40°C to +85°C) and SOIC package. Confirm AVDD is strictly regulated between 4.75 V and 5.25 V. Ensure DVDD supports 2.7 V to 5.25 V. Check datasheet for specific calibration limits and power supply rejection ratios relevant to the application environment.

Selection Notes

Select this component for high-precision DC measurements requiring low drift. The AD7730 is suitable for bridge transducers needing direct signal conditioning. Consider the AD7730L if a lower master clock frequency (2.4576 MHz) is required. Verify that the required input voltage ranges fit within the specified unipolar or bipolar limits defined by the PGA settings.

Part Context

The AD7730 is part of Analog Devices' bridge transducer ADC family. It integrates a Sigma-Delta modulator, programmable gain amplifier, and digital filter into a single 24-pin package. The B-version specifies performance over the industrial temperature range. It is designed to simplify the interface between low-level sensors and microcontrollers.

Replacement Considerations

The AD7730L is a compatible variant with different clock specifications (2.4576 MHz vs 4.9152 MHz). Other members of the AD773x family may offer different channel counts or pinouts; verify register compatibility and pin assignments before substitution.

FAQ

What are the available analog input voltage ranges?

The device supports four unipolar ranges (0 to +10 mV, +20 mV, +40 mV, +80 mV) and four bipolar ranges (±10 mV, ±20 mV, ±40 mV, ±80 mV), determined by the PGA gain settings.

How does the on-chip DAC function?

The 6-bit DAC allows the removal of TARE voltages by adding or subtracting a programmed voltage from the analog input signal before it reaches the PGA.

What is the purpose of the ACX outputs?

The ACX outputs provide signals to control the reversing of bridge excitation polarity in AC-excited bridge applications, enabling chopper stabilization techniques.