Analog Devices Inc. AD7711AARZ

Overview

AD7711AARZ from Analog Devices is a 24-bit sigma-delta analog-to-digital converter with integrated programmable gain amplifier (PGA), dual differential inputs, on-chip 2.5 V reference, and 400 µA RTD excitation current source. It delivers ±0.0015% integral nonlinearity, 100 dB common-mode rejection at DC, and operates from single or dual supplies (AVDD = 5–10 V, VSS = 0 or –5 V). It is designed for high-accuracy RTD-based temperature measurement systems.

For engineers reviewing the AD7711AARZ datasheet, AD7711AARZ pinout, AD7711AARZ application, or AD7711AARZ equivalent, key selection considerations include its 24-bit no-missing-codes performance, software-configurable filter notch (10–60 Hz), PGA gain range (1–128), bidirectional serial interface, and integrated transducer burnout detection.

Technical Context

The AD7711AARZ employs a charge-balancing sigma-delta architecture with auto-zeroed modulator and on-chip digital filter whose first notch frequency is programmable via control register bits FS0–FS11. Its two differential analog input channels (AIN1±, AIN2±) share a single PGA and modulator, enabling time-multiplexed dual-channel acquisition.

It integrates a 400 µA RTD excitation current source (pin 17), 4.5 mA transducer burnout current (pin 7), and VBIAS bias voltage input (pin 13) to stabilize common-mode operation across supply configurations. The device supports both self-calibration (internal zero/full-scale references) and system calibration (user-applied external references), with read/write access to on-chip calibration registers via serial interface.

Key Specifications

Pinout & Package

AD7711AARZ is housed in a 24-lead SOIC package (RW-24 footprint, 0.3-inch width, RoHS-compliant).

Key Features

Applications

Equivalent & Alternatives

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

Compared with AD7791BRUZ and ADS1248IPWR, the AD7711AARZ uniquely combines dual differential inputs, integrated 400 µA RTD current source, on-chip 2.5 V reference, and burnout detection-enabling complete, compact, and calibrated RTD front ends without supplemental ICs.

Availability

AD7711AARZ is available at Aetrix Electronics and suitable for RTD temperature monitoring, industrial process transmitters, and multi-sensor data acquisition systems requiring stable component supply, long-term lifecycle support, and traceable sourcing.

Supply support for AD7711AARZ 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, communications, automotive, and consumer markets since 1965.

The AD7711AARZ belongs to Analog Devices' precision sigma-delta ADC product line, engineered specifically for low-frequency, high-accuracy measurement applications including RTD, thermocouple, and bridge sensor interfaces.

FAQ

What is the maximum sampling rate of the AD7711AARZ?

The AD7711AARZ does not operate at a fixed sampling rate; its output data rate depends on the selected digital filter notch frequency and master clock (MCLK IN). With MCLK IN = 10 MHz and filter notch = 60 Hz, the effective output rate is approximately 16.6 samples per second. Lower notch frequencies (e.g., 10 Hz) reduce the rate further, while higher notches (e.g., 500 Hz) increase it-but at the cost of reduced resolution (15-bit no missing codes at 500 Hz). The AD7711AARZ is optimized for precision, not speed.

Does the AD7711AARZ support both unipolar and bipolar input ranges?

Yes, the AD7711AARZ supports both unipolar (0 to +VREF/GAIN) and bipolar (±VREF/GAIN) input ranges. The selection is controlled by the B/U bit in the 24-bit control register. In unipolar mode, output coding is natural binary; in bipolar mode, it uses offset binary. Input range validity depends on gain setting and reference voltage-e.g., at GAIN = 1 and VREF = 2.5 V, unipolar spans 0–2.5 V and bipolar spans ±2.5 V relative to AIN(–).

Can the AD7711AARZ operate from a single 5 V supply?

Yes, the AD7711AARZ supports single-supply operation: tie VSS to AGND, set AVDD = 5 V ±5%, and ensure analog inputs remain > –30 mV relative to VSS. For negative input capability (e.g., bipolar measurements), VSS must be driven negative (e.g., –5 V), enabling input signals down to –VREF. The internal 2.5 V reference (REF OUT) remains functional in both configurations and can power external circuitry up to 1 mA.

How does the AD7711AARZ handle calibration for long-term stability?

The AD7711AARZ provides three calibration modes: self-calibration (uses internal zero/full-scale references), system calibration (uses user-applied external references), and background calibration (continuous zero correction during normal operation). All modes allow reading and writing of on-chip calibration registers via the serial interface, enabling firmware-driven recalibration in the field. Full-scale drift is reduced to 0.3 mV/°C (typical) for gains ≥4, and zero drift to 0.25 mV/°C-significantly improving long-term stability without hardware intervention.

Is the AD7711AARZ pin-compatible with other devices in the AD77xx family?

No, the AD7711AARZ is not pin-compatible with other AD77xx-series converters such as the AD7710 or AD7712. Its 24-pin SOIC layout-including dedicated RTD CURRENT (Pin 17), VBIAS (Pin 13), and dual MCLK pins-is unique to the AD7711A. While functional similarities exist (e.g., sigma-delta architecture, serial interface), pin assignments, register maps, and feature sets differ. Migration requires PCB redesign and firmware adaptation-not drop-in replacement.