AD7771-4BCPZ-RL

Overview

The AD7771-4BCPZ-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) in high resolution mode and includes a sample rate converter (SRC) for coherent sampling with 15.2 µSPS resolution. It operates on bipolar (±1.65 V) or unipolar (3.3 V) analog supplies and a 1.8 V to 3.6 V digital I/O supply. Key performance metrics include 107 dB dynamic range at 32 kSPS (sinc5 filter), -109 dB THD, ±8 ppm FSR INL, and ±15 µV offset error. It integrates a 2.5 V reference and a 12-bit SAR ADC for diagnostics.

Feature Summary

• Integrated 12-bit SAR ADC enables system and chip diagnostics without decommissioning primary measurement channels.
• Sample Rate Converter (SRC) allows fine-resolution ODR adjustment to maintain coherency with line frequency drift.
• Dual power modes optimize the balance between power dissipation and dynamic range performance.
• Adjustable phase synchronization ensures precise alignment across multiple channels.

Applications

• Power quality and measurement applications
• General-purpose data acquisition
• Electroencephalography (EEG)
• Industrial process control

Procurement Notes

Verify the specific suffix '4B' against the manufacturer's current ordering guide to confirm package type, temperature grade, and reel specifications. Ensure the procurement documentation matches the exact part number to avoid functional discrepancies related to manufacturing revisions or regional compliance requirements.

Selection Notes

Select this component when simultaneous multi-channel sampling with ultralow input current is required. Evaluate the trade-off between high resolution mode (16.6 mW/channel) and low power mode (5.25 mW/channel) based on thermal constraints. Confirm that the available clock frequencies support the desired decimation rates and latency requirements for the sinc3 or sinc5 filters.

Part Context

The AD7771 belongs to a family of high-performance sigma-delta ADCs designed for precision signal conditioning. It distinguishes itself by combining eight independent 24-bit converters with a dedicated diagnostic SAR ADC on a single die. This architecture supports complex industrial and medical systems requiring high channel count and rigorous self-monitoring capabilities.

Replacement Considerations

Consult the official Analog Devices cross-reference documentation for verified substitute part numbers. Do not assume pin compatibility or register-level equivalence with other ADC families without explicit datasheet confirmation.

FAQ

How does the Sample Rate Converter (SRC) function?

The SRC allows fine-resolution control over the output data rate (ODR) with a resolution of 15.2 × 10⁻⁶ SPS. It is programmed via the SPI interface to maintain coherency with input signals, such as compensating for 0.01 Hz line frequency drift.

What is the purpose of the integrated SAR ADC?

The 12-bit SAR ADC is used for system and chip diagnostics. It can validate the measurements of the primary Σ-Δ ADCs without decommissioning any of the eight main channels, which is critical for functional safety applications.

Can the AD7771 operate with external references?

Yes, while it includes an internal 2.5 V reference, it accepts an external VREF voltage ranging from 1 V up to 3.6 V. The external reference buffer can be enabled or disabled to optimize power consumption.