Analog Devices Inc. AD7765BRUZ

Overview

AD7765BRUZ from Analog Devices is a 24-bit, sigma-delta analog-to-digital converter (ADC) with on-chip differential amplifier, reference buffer, and full-band FIR filter. It delivers 112 dB dynamic range at 156 kSPS, supports pin-selectable 128×/256× oversampling, and operates across −40°C to +85°C in industrial data acquisition systems requiring high-resolution ac/dc signal capture.

For engineers reviewing the AD7765BRUZ datasheet, AD7765BRUZ pinout, AD7765BRUZ application, or AD7765BRUZ equivalent, key selection criteria include its 156 kSPS fully filtered output rate, ±3.2768 V differential input range with 4.096 V external reference, low-power mode preserving bandwidth, daisy-chain capability, and synchronization support for multi-device timing alignment.

Technical Context

The AD7765BRUZ employs a fourth-order Σ-Δ modulator sampling at up to 40 MSPS (MCLK/2), followed by three cascaded FIR filters providing programmable decimation (128× or 256×). Its digital filtering achieves stop-band attenuation of −120 dB at 128× and −115 dB at 256×, with pass-band ripple ≤0.1 dB and −3 dB bandwidth at ODR × 0.4096 kHz.

It integrates a fully differential amplifier (125 kHz 0.1 dB flatness, >1 MΩ input impedance) and reference buffer to reduce external signal conditioning. The modulator inputs accept ±3.2768 V p-p differential signals biased at 2.048 V common-mode, while the overrange alert pin provides real-time saturation detection without software polling.

Key Specifications

Pinout & Package

AD7765BRUZ is housed in a 28-lead TSSOP package (4.4 mm × 9.7 mm), optimized for high-density PCB layouts and thermal performance on 2s2p boards (θ_JA = 71.1°C/W).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar high-resolution sigma-delta ADC applications.

Compared with AD7764BRUZ and AD7768-1BRUZ, the AD7765BRUZ uniquely balances 156 kSPS throughput, 112 dB performance, and integrated signal conditioning-making it optimal for single-channel, bandwidth-constrained, high-fidelity acquisition where external amplifiers add cost and error sources.

Availability

AD7765BRUZ is available at Aetrix Electronics and suitable for vibration analysis, portable instrumentation, and structural health monitoring requiring stable component supply, long-term lifecycle support, and consistent parametric performance across production batches.

Supply support for AD7765BRUZ includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Analog Devices is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, serving industrial, automotive, communications, and healthcare markets since 1965.

The AD7765BRUZ belongs to Analog Devices' precision sigma-delta ADC product line, engineered specifically for high-speed, high-dynamic-range data acquisition systems demanding minimal external components and deterministic timing behavior.

FAQ

What is the maximum output data rate of the AD7765BRUZ and under what conditions is it achieved?

The AD7765BRUZ achieves a maximum fully filtered output data rate of 156.25 kSPS when configured with 128× decimation and a 40 MHz master clock (MCLK). This rate is confirmed in the datasheet's Specifications table (Rev. D, page 4) and corresponds to the highest usable sample rate with full digital filtering applied. The AD7765BRUZ maintains this rate in both normal and low-power modes, making it suitable for real-time broadband signal capture without compromising resolution.

Does the AD7765BRUZ require an external reference voltage, and what is the recommended value?

Yes, the AD7765BRUZ requires an external reference voltage applied to the VREF+ pin. The datasheet specifies 4.096 V as the nominal reference voltage, which establishes a ±3.2768 V differential input range and 2.048 V common-mode bias point. Using this precise reference ensures guaranteed 24-bit monotonicity and optimal dynamic range performance. Deviations from 4.096 V will proportionally scale the input range and affect absolute accuracy unless digitally compensated.

How does the on-chip differential amplifier in the AD7765BRUZ simplify sensor interfacing?

The on-chip differential amplifier in the AD7765BRUZ provides >1 MΩ input impedance, 125 kHz 0.1 dB flatness, and fixed 2.048 V common-mode output-enabling direct connection of low-output-impedance sensors like IEPE accelerometers or Wheatstone bridge transducers without external op-amps. This reduces component count, PCB area, noise pickup, and calibration complexity. The AD7765BRUZ amplifier also buffers the reference path, improving PSRR and stability versus discrete solutions.

Can multiple AD7765BRUZ devices be synchronized, and how is this implemented?

Yes, multiple AD7765BRUZ devices can be precisely synchronized using the dedicated SYNC pin. A falling edge on SYNC resets the internal digital filter state across all connected devices, ensuring deterministic phase alignment of output data streams. This is essential for coherent multi-channel acquisition in applications like phased-array sensing or distributed structural monitoring. The AD7765BRUZ datasheet confirms SYNC functionality in Sections "Synchronization" and "Functional Block Diagram."

What power supply configurations does the AD7765BRUZ support, and how do they map to internal blocks?

The AD7765BRUZ uses five independent supplies: AVDD1 (2.5 V for modulator), AVDD2 (5 V general analog), AVDD3 (5 V for differential amplifier), AVDD4 (5 V for reference buffer), and DVDD (2.5 V for digital core). This separation isolates noise-sensitive analog sections (modulator, amplifier, reference) from digital switching noise. Each supply must be decoupled per the datasheet's Pin Configuration section (page 9), with specific capacitor values and grounding recommendations to maintain 112 dB dynamic range performance.