Analog Devices Inc. AD7711ASQ

Overview

AD7711ASQ 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 CMR at DC, and operates from –55°C to +125°C in a hermetic CERDIP-24 package. It is designed for high-accuracy RTD-based temperature measurement systems requiring self-calibration and low-noise signal conditioning.

For engineers reviewing the AD7711ASQ datasheet, AD7711ASQ pinout, AD7711ASQ application, or AD7711ASQ equivalent, this page provides verified technical context, real-world design meaning of key specs, validated pin functions, confirmed alternative parts with documented differences, and supply-chain support for industrial embedded and aerospace-grade deployments.

Technical Context

The AD7711ASQ employs a charge-balancing sigma-delta architecture with auto-zeroed modulator and on-chip digital filter whose first notch is programmable (10 Hz to 1 kHz), enabling precise rejection of 50/60 Hz line interference. Its two-channel differential input front end supports gains from 1 to 128 and accepts unipolar (0 to +VREF) or bipolar (±VREF) signals depending on B/U bit setting.

It integrates a 400 µA RTD excitation current source with ±20% initial tolerance and 20 ppm/°C drift, plus a 4.5 mA transducer burnout detection current. Calibration is supported via self-, system-, and background modes, with full read/write access to on-chip calibration registers over a bidirectional serial interface operating in self-clocking or external-clocking mode.

Key Specifications

Pinout & Package

AD7711ASQ is housed in a 24-lead, 0.3-inch-wide hermetic CERDIP package (Q-24). Pin assignments are fully validated per Analog Devices' official datasheet Rev. D.

Key Features

Applications

Equivalent & Alternatives

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

Compared with AD7792BRUZ and ADS1248IPWR, the AD7711ASQ uniquely combines hermetic CERDIP packaging, –55°C to +125°C operation, integrated 400 µA RTD current, and 2.5 V reference in a single chip-making it the only option qualified for mission-critical aerospace and downhole instrumentation where reliability and calibration integrity are non-negotiable.

Availability

AD7711ASQ is available at Aetrix Electronics and suitable for industrial temperature monitoring, aerospace cryogenic sensing, smart sensor transmitters, and medical instrumentation requiring stable component supply across extended temperature ranges and long product lifecycles.

Supply support for AD7711ASQ 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, Inc. is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, headquartered in Norwood, MA.

The AD7711ASQ belongs to Analog Devices' precision sigma-delta ADC product line, engineered specifically for high-accuracy, low-frequency measurement systems requiring integrated signal conditioning, robust calibration, and extended environmental qualification.

FAQ

What is the guaranteed resolution and linearity performance of the AD7711ASQ?

The AD7711ASQ guarantees 24-bit no missing codes performance when the digital filter notch is set to ≤60 Hz. Its integral nonlinearity is specified at ±0.0015% FSR maximum at 25°C, ensuring less than 1 LSB error across full scale. This performance is maintained over the full –55°C to +125°C operating range through on-chip calibration, and the AD7711ASQ datasheet confirms these values under defined test conditions including AVDD = 5 V, MCLK IN = 10 MHz, and VREF = 2.5 V.

Does the AD7711ASQ support both unipolar and bipolar input configurations?

Yes, the AD7711ASQ supports both unipolar and bipolar input ranges via the B/U bit in its 24-bit control register. When B/U = 1, the input range is unipolar (0 to +VREF/GAIN); when B/U = 0, it is bipolar (±VREF/GAIN). The device automatically adjusts coding: natural binary for unipolar mode and offset binary for bipolar mode. This flexibility allows the AD7711ASQ to interface directly with grounded or floating RTD bridges without external level-shifting circuitry.

How does the AD7711ASQ handle RTD excitation and open-circuit detection?

The AD7711ASQ integrates a dedicated 400 µA constant-current source on the RTD CURRENT pin for RTD excitation, with ±20% initial tolerance and 20 ppm/°C drift. For open-circuit detection, it provides a separate 4.5 mA burnout current source on the AIN1(+) pin, configurable via the control register. This dual-current architecture enables simultaneous excitation and diagnostics-allowing the AD7711ASQ to detect RTD wire breaks while maintaining accurate measurement, a capability explicitly documented in the AD7711ASQ functional description and pin function table.

Can the AD7711ASQ operate from a single supply, and what are the voltage requirements?

Yes, the AD7711ASQ supports single-supply operation by tying VSS to AGND. In this configuration, analog inputs must remain > –30 mV relative to VSS, and AVDD must be between 5 V and 10 V (±5%). DVDD requires +5 V (±5%), and must not exceed AVDD by more than 0.3 V. The AD7711ASQ datasheet confirms single-supply functionality in the General Description section and specifies absolute maximum ratings for AVDD-to-VSS (≤12 V) and input voltage range (VSS – 0.3 V to AVDD + 0.3 V).

What calibration modes does the AD7711ASQ support, and how are they triggered?

The AD7711ASQ supports three calibration modes: self-calibration (MD2–MD0 = 001), system calibration (MD2–MD0 = 010), and background calibration (MD2–MD0 = 011), all initiated by writing to the control register. Self-calibration uses internal shorted inputs and VREF; system calibration applies user-provided zero/full-scale voltages to the selected channel; background calibration runs continuously during normal conversion. DRDY falling edge signals completion of self- and system-calibration sequences. These modes and their control logic are fully detailed in the AD7711ASQ Control Register section (Rev. D, p.9).