Analog Devices Inc. AD7712AQ

Overview

AD7712AQ from Analog Devices is a 24-bit sigma-delta analog-to-digital converter (ADC) with integrated programmable-gain amplifier (PGA), dual analog input channels, and on-chip 2.5 V reference. It delivers 0.0015% integral nonlinearity, supports ±4 V_REF/GAIN high-level inputs and differential low-level transducer inputs, and operates from single or dual supplies (AVDD = +5 to +10 V, VSS = 0 or –5 V). It is used in precision industrial measurement systems requiring self-calibration and high noise rejection.

For engineers reviewing the AD7712AQ datasheet, AD7712AQ pinout, AD7712AQ application, or AD7712AQ equivalent, key selection considerations include its 24-bit no-missing-codes performance at ≤60 Hz filter notch, programmable gain (1–128), dual-channel architecture with differential AIN1(±), 100 dB 50/60 Hz normal-mode rejection, and hardware STANDBY power-down mode (100 µW typical).

Technical Context

The AD7712AQ employs a charge-balancing sigma-delta modulator with on-chip digital filtering, where the first notch frequency is software-programmable via control register bits to adjust cutoff and settling time. Its analog front end includes a proprietary PGA for AIN1(±) and a resistor-based attenuator for AIN2, enabling simultaneous high- and low-level signal acquisition.

It features bidirectional serial interface (SCLK/MODE/RFS/TFS/SDATA/DRDY), internal/external reference selection, and three calibration modes-self-, system-, and background-allowing read/write access to on-chip calibration registers. The device uses LC2MOS process technology and supports both unipolar and bipolar coding (offset binary for bipolar, natural binary for unipolar).

Key Specifications

Pinout & Package

AD7712AQ is housed in a 24-lead CERDIP (Q-24) package with 0.3-inch width, rated for –40°C to +85°C operation.

Key Features

Applications

Equivalent & Alternatives

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

Compared with AD7712AQ, AD7714BRUZ offers more input channels but requires external reference design, while ADS1258IPWR trades deep-noise rejection and diagnostic features for speed and channel count-making AD7712AQ optimal for low-speed, high-accuracy dual-input industrial sensing with minimal external components.

Availability

AD7712AQ is available at Aetrix Electronics and suitable for smart transmitters, process control systems, and portable industrial instruments requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for AD7712AQ 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, founded in 1965 and headquartered in Wilmington, MA.

The AD7712AQ belongs to Analog Devices' precision sigma-delta ADC product line, designed specifically for low-frequency industrial measurement applications demanding high resolution, integrated signal conditioning, and robust noise rejection in harsh environments.

FAQ

What is the maximum guaranteed resolution of the AD7712AQ at different filter notch frequencies?

The AD7712AQ guarantees 24-bit no-missing-codes performance only when the digital filter's first notch is set to ≤60 Hz. At 100 Hz notch, resolution drops to 22 bits; at 250 Hz, it is 18 bits; at 500 Hz, 15 bits; and at 1 kHz, 12 bits. These values are specified in the datasheet's Static Performance table and reflect trade-offs between speed and effective resolution due to modulator and filter architecture.

Can the AD7712AQ operate from a single 5 V supply, and what are the input voltage limitations in that configuration?

Yes, the AD7712AQ supports single-supply operation by tying VSS to AGND. In this mode, the AIN1(±) differential input must remain > –30 mV relative to VSS (i.e., > –30 mV vs. AGND), and absolute voltages must stay within AVDD + 30 mV and VSS – 30 mV. AIN2 accepts 0 V to 4 V_REF (up to ±10 V at GAIN = 1, V_REF = 2.5 V), referenced to AGND. AVDD must be +5 V ±5% for full specification compliance.

How does the AD7712AQ handle transducer burnout detection, and which pins are involved?

The AD7712AQ provides transducer burnout detection via a 4.5 µA nominal current source connected to the AIN1(+) pin. This feature is enabled/disabled through the control register's BURN bit. When active, the current source pulls AIN1(+) toward AVDD, causing a measurable voltage shift if the sensor becomes open-circuit. No external components are required-the function relies solely on internal circuitry and AIN1(+) pin behavior.

What are the key differences between hardware STANDBY mode and software power-down (PD bit) in the AD7712AQ?

Hardware STANDBY (driving the STANDBY pin low) reduces total supply current to <50 µW and fully shuts down analog and digital circuitry, enabling fastest wake-up. Software power-down (setting PD bit in control register) draws ~8 mW-orders of magnitude higher-and retains register contents but disables conversion. Hardware STANDBY is preferred for ultra-low-power sleep states; software PD is used for brief pauses during active operation.

Does the AD7712AQ support both unipolar and bipolar input configurations, and how is the mode selected?

Yes, the AD7712AQ supports both unipolar and bipolar input ranges via the B/U bit in the control register. When B/U = 1, AIN1 accepts 0 V to V_REF/GAIN (unipolar); when B/U = 0, it accepts ±V_REF/GAIN (bipolar). Output coding follows accordingly: natural binary for unipolar, offset binary for bipolar. AIN2 similarly supports ±4 V_REF/GAIN (bipolar) or 0 to 4 V_REF/GAIN (unipolar), with identical B/U bit control.