AD7771BCPZ-RL

Overview

The AD7771BCPZ-RL is an 8-channel, 24-bit simultaneous sampling analog-to-digital converter (ADC) from Analog Devices. It features a programmable gain amplifier (PGA) with gains of 1, 2, 4, and 8 per channel, supporting single-ended or true differential inputs. The device offers up to 128 kSPS output data rate (ODR) with a sample rate converter (SRC) providing resolution down to 15.2 × 10⁻⁶ SPS for coherent sampling. Key performance metrics include 107 dB dynamic range at 32 kSPS in high-resolution mode, -109 dB THD, and ±8 ppm FSR INL. It operates on bipolar (±1.65 V) or unipolar (3.3 V) analog supplies and includes a 12-bit SAR ADC for diagnostics.

Feature Summary

• Simultaneous sampling across eight channels with integrated low-latency sinc3 and sinc5 digital filters.
• Ultralow dc input current allowing direct sensor connection without signal distortion.
• Integrated sample rate converter enabling fine-resolution control for coherent sampling applications.
• Built-in 12-bit SAR ADC dedicated to system and chip diagnostics without decommissioning measurement channels.

Applications

• Power quality and measurement applications
• Electroencephalography (EEG)
• Industrial process control

Procurement Notes

Verify the BC suffix indicates the specific temperature grade and packaging configuration required for your design. Confirm the RL suffix denotes tape-and-reel packaging suitable for automated assembly. Ensure the ordering part number matches the exact voltage and package variant specified in the manufacturer's official documentation before finalizing procurement.

Selection Notes

Select this component when simultaneous multi-channel acquisition with high precision is required. The internal PGA allows mapping various sensor outputs to the full-scale range. Consider the high-resolution mode for maximum dynamic range or low-power mode for reduced consumption. Verify that the supply voltages and interface requirements align with the system architecture.

Part Context

The AD7771 belongs to a family of high-performance sigma-delta ADCs designed for demanding industrial and medical applications. It shares architectural similarities with models like the AD7770 and AD7779 but offers specific channel counts and diagnostic features. The BC suffix typically denotes a specific temperature range and package type within the broader AD7771 product line.

Replacement Considerations

Direct substitutes may include other ADI 8-channel 24-bit ADCs such as the AD7770 or AD7779, provided pin compatibility and feature sets match. Verify register compatibility and performance specifications against the original design requirements before substitution.

FAQ

How does the Sample Rate Converter (SRC) benefit power quality applications?

The SRC allows fine-resolution control over the output data rate, enabling coherent sampling. This maintains synchronization with line frequency changes (e.g., 0.01 Hz drift), preventing spectral leakage in FFT calculations for accurate power analysis.

What is the purpose of the integrated 12-bit SAR ADC?

The SAR ADC is used for system and chip diagnostics. It can validate the measurements of the main Σ-Δ ADCs without decommissioning any of the eight primary measurement channels, which is critical for functional safety applications.

Can the AD7771 handle both single-ended and differential inputs?

Yes, each channel supports both single-ended and true differential input configurations. The PGA gain settings allow users to map lower amplitude signals into the full-scale input range regardless of the input type.