Analog Devices Inc. AD7709ARU-REEL

Overview

AD7709ARU-REEL from Analog Devices is a 16-bit sigma-delta ADC with integrated programmable gain amplifier (PGA), three switchable matched excitation current sources (200 µA, 200 µA, 25 µA), low-side power switches, and a 4-bit digital I/O port. It supports fully differential or pseudo-differential input configurations across ±20 mV to ±2.56 V ranges and delivers 13-bit p-p resolution at 20 Hz on ±20 mV range-optimized for precision sensor front-end applications including RTD-based temperature measurement and 4–20 mA loop interfaces.

For engineers reviewing the AD7709ARU-REEL datasheet, AD7709ARU-REEL pinout, AD7709ARU-REEL application, or AD7709ARU-REEL equivalent, key selection considerations include simultaneous 50/60 Hz rejection capability at 19.79 Hz update rate, rail-to-rail buffered analog inputs, VREF Select™ for ratiometric operation, ISOURCE Select™ for excitation control, and SPI/QSPI/MICROWIRE-compatible 3-wire serial interface with Schmitt-triggered SCLK.

Technical Context

The AD7709ARU-REEL implements a chopper-stabilized sigma-delta modulator with Sinc³ digital filtering, enabling 16-bit no-missing-codes performance and ±2 ppm typical offset error drift. Its internal 32.768 kHz crystal oscillator and PLL generate precise timing for programmable output data rates from 5.35 Hz to 105.03 Hz.

Input signal conditioning is handled by a rail-to-rail input buffer and PGA with gain settings from 1 to 128, supporting both unipolar and bipolar modes. Excitation current sources are ratioed to VDD and feature ±2.5% initial matching between IEXC1/IEXC2 and ±5% matching between 8×IEXC3 and IEXC1/IEXC2-critical for accurate V_BE and 3-wire RTD measurements.

Key Specifications

Pinout & Package

The AD7709ARU-REEL is housed in a 24-lead TSSOP (RU-24) package with exposed pad for thermal management. Pin assignments follow the standard top-view layout defined in Analog Devices' ordering guide and pin function descriptions.

Key Features

Applications

Equivalent & Alternatives

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

Compared with AD7709ARU-REEL, AD7190BRUZ trades integrated excitation for higher resolution and wider bandwidth, while ADS124S08IPWR reduces power but requires interface redesign-making AD7709ARU-REEL the balanced choice for industrial sensor front-ends needing self-contained excitation, robust noise rejection, and SPI interoperability.

Availability

AD7709ARU-REEL is available at Aetrix Electronics and suitable for temperature measurement, pressure transducer digitization, and portable instrumentation requiring stable component supply and long-term industrial lifecycle support.

Supply support for AD7709ARU-REEL 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 AD7709ARU-REEL belongs to Analog Devices' precision sigma-delta ADC product line, designed specifically for low-frequency sensor signal conditioning in industrial, instrumentation, and process control applications where integration, noise immunity, and ratiometric accuracy are critical.

FAQ

What is the maximum update rate supported by the AD7709ARU-REEL?

The AD7709ARU-REEL supports a maximum output data rate of 105.03 Hz, achieved when the Sinc³ filter's SF register is set to its minimum value of 13. This corresponds to a conversion time of 9.52 ms and is ideal for fast-response applications such as dynamic pressure monitoring where latency must be minimized while retaining 16-bit resolution.

Does the AD7709ARU-REEL support both 3 V and 5 V operation?

Yes, the AD7709ARU-REEL is fully specified for single-supply operation across two voltage ranges: 2.7 V to 3.6 V and 4.75 V to 5.25 V. At 3 V, typical supply current is 1.25 mA; at 5 V, it rises to 1.45 mA. The device maintains full functionality-including excitation current accuracy, reference rejection, and digital I/O levels-across both rails without configuration changes.

How does the AD7709ARU-REEL achieve simultaneous 50 Hz and 60 Hz rejection?

The AD7709ARU-REEL achieves simultaneous 50 Hz and 60 Hz rejection by operating at an update rate of 19.79 Hz (SF = 69), which places Sinc³ filter notches at harmonics that attenuate both frequencies to ≥60 dB. This eliminates the need for external notch filters or dual-mode firmware switching-simplifying design for globally deployed equipment subject to variable mains frequencies.

Can the AD7709ARU-REEL drive RTD sensors directly?

Yes, the AD7709ARU-REEL integrates three matched excitation current sources (200 µA, 200 µA, 25 µA) with ±2.5% initial matching and 20 ppm/°C drift matching-enabling direct 2-, 3-, or 4-wire RTD interfacing. Its REFIN1(±) and REFIN2(±) inputs allow true ratiometric measurement, eliminating errors from reference voltage drift during temperature sweeps.

What package type is used for the AD7709ARU-REEL?

The AD7709ARU-REEL is supplied in a 24-lead TSSOP package (RU-24 footprint), measuring 7.8 mm × 4.4 mm × 1.2 mm. This RoHS-compliant, surface-mount package features an exposed thermal pad for enhanced heat dissipation in high-density PCB layouts and is compatible with standard reflow soldering profiles.