Analog Devices Inc. AD7731BRUZ-REEL7

Overview

AD7731BRUZ-REEL7 from Analog Devices is a 24-bit sigma-delta analog-to-digital converter optimized for high-precision process control front ends. It integrates a programmable-gain amplifier (PGA), buffered differential inputs, a 22-tap FIR digital filter, FASTStep™ mode for rapid channel settling, and supports 7 unipolar/bipolar input ranges down to ±20 mV. It delivers 16 bits peak-to-peak resolution at 800 Hz output rate and operates from a single +5 V analog supply with 2.7–5.25 V digital supply.

For engineers reviewing the AD7731BRUZ-REEL7 datasheet, AD7731BRUZ-REEL7 pinout, AD7731BRUZ-REEL7 application, or AD7731BRUZ-REEL7 equivalent, this page provides verified technical context, real-world timing and noise performance, calibrated drift specs (≤5 nV/°C offset drift), true pin-function mapping for TSSOP-24, and validated alternatives for industrial instrumentation design.

Technical Context

The AD7731BRUZ-REEL7 implements a two-stage digital filter: a configurable SINC³ modulator followed by either a fixed 22-tap FIR filter (default) or FASTStep™ adaptive filter for step-input transient response. Its on-chip PGA supports gain settings enabling direct transducer interfacing across ±20 mV to ±1.28 V full-scale ranges.

It features three buffered differential analog input channels (configurable as five pseudo-differential inputs), a differential reference input supporting +2.5 V or +5 V nominal, and dual calibration modes - self-calibration reducing offset to ≤3 µV and system calibration achieving noise-limited accuracy. The device uses SPI-compatible 3-wire serial interface with polarity-selectable clock (POL pin) and supports SYNC-driven multi-device synchronization.

Key Specifications

Pinout & Package

AD7731BRUZ-REEL7 is housed in a 24-lead TSSOP package (RU-24), 4.4 mm × 7.8 mm, 0.65 mm pitch, RoHS-compliant, with exposed pad for thermal enhancement.

Key Features

Applications

Equivalent & Alternatives

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

Compared with AD7731BRUZ-REEL7, AD7172-2BRUZ offers superior resolution and noise but requires external signal conditioning for low-level transducers, while ADS1258IRTCT provides faster throughput and more channels but sacrifices industrial-grade drift specs and adaptive filtering - making AD7731BRUZ-REEL7 optimal for cost-sensitive, thermally demanding process control front ends.

Availability

AD7731BRUZ-REEL7 is available at Aetrix Electronics and suitable for process control systems, PLC analog input modules, and high-accuracy industrial instrumentation requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for AD7731BRUZ-REEL7 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 AD7731BRUZ-REEL7 belongs to Analog Devices' precision sigma-delta ADC product line, designed specifically for ruggedized analog front ends in process automation, where low drift, integrated transducer interface, and deterministic settling are mandatory.

FAQ

What is the maximum output data rate supported by the AD7731BRUZ-REEL7?

The AD7731BRUZ-REEL7 supports programmable output rates up to 6.4 kHz in SKIP mode, where only the SINC³ filter is active. In standard mode with both SINC³ and 22-tap FIR filtering enabled, the maximum rate is 800 Hz - delivering 16 bits peak-to-peak resolution. The device's FASTStep™ mode maintains 13-bit p-p resolution during 1 ms channel switching at 800 Hz, making AD7731BRUZ-REEL7 suitable for time-critical multiplexed sensor systems.

Does the AD7731BRUZ-REEL7 require an external crystal or can it operate with an external clock?

Yes, the AD7731BRUZ-REEL7 supports both configurations: a crystal or ceramic resonator can be connected between MCLK IN and MCLK OUT pins, or a CMOS-compatible external clock (1–5 MHz) can be applied directly to MCLK IN with MCLK OUT left unconnected. The device is specified for optimal performance at 4.9152 MHz, and AD7731BRUZ-REEL7's internal clock generation circuitry tolerates ±0.1% frequency variation without compromising integral nonlinearity or noise performance.

How does the burnout detection feature work on the AD7731BRUZ-REEL7?

The AD7731BRUZ-REEL7 integrates matched 100 nA current sources on AIN1(+) and AIN1(–) pins. When enabled, these currents force a measurable voltage shift across an open-circuit transducer - detectable as out-of-range output codes. The burnout function is configurable via register bits and operates independently of conversion mode, allowing continuous fault monitoring during standby or active measurement. This capability is unique to AD7731BRUZ-REEL7 among its class and eliminates need for external current sources.

Can the AD7731BRUZ-REEL7 operate with a 3.3 V digital supply while using a 5 V analog supply?

Yes, AD7731BRUZ-REEL7 supports split supplies: AVDD = +5 V (nominal) and DVDD = +2.7 V to +5.25 V. At DVDD = +3.3 V, digital I/O levels comply with 3.3 V logic families (VINH ≥ 2.0 V, VOL ≤ 0.4 V at 100 µA sink), and power consumption drops to 3.2 mA (DVDD current) in normal mode. All serial interface timing parameters remain valid, and AD7731BRUZ-REEL7 maintains full 24-bit performance - enabling hybrid supply architectures common in modern industrial controllers.

What calibration modes are available on the AD7731BRUZ-REEL7 and how do they affect accuracy?

AD7731BRUZ-REEL7 offers three calibration modes: self-calibration (zeros offset and corrects gain using internal references), system calibration (uses external known voltage for higher accuracy), and no calibration (raw conversion). Self-calibration reduces offset error to ≤3 µV and gain error to <100 ppm; system calibration achieves noise-limited accuracy - e.g., <1 µV offset residual. Calibration is initiated via register writes and takes <100 ms. These functions are integral to AD7731BRUZ-REEL7's architecture and require no external components.