Analog Devices Inc. AD7709BRUZ

Overview

AD7709BRUZ 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, and 25 µA), low-side power switches, and a 4-bit digital I/O port - designed for precision sensor front-end applications including RTD, thermocouple, and bridge transducer measurement. It supports ±20 mV to ±2.56 V input ranges, simultaneous 50 Hz/60 Hz rejection at 19.79 Hz update rate, and operates from single 3 V or 5 V supply.

For engineers reviewing the AD7709BRUZ datasheet, AD7709BRUZ pinout, AD7709BRUZ application, or AD7709BRUZ equivalent, this page delivers verified technical context, real-world design meaning of key specs, validated pin functions, confirmed alternative options, and supply-ready availability details - all grounded in the official AD7709 Rev. A datasheet and Analog Devices' product documentation.

Technical Context

The AD7709BRUZ implements a chopper-stabilized sigma-delta ADC architecture with Sinc³ digital filtering, enabling 16-bit no-missing-codes performance and ultra-low offset drift (±10 nV/°C). Its modulator sampling rate is fixed at 32.768 kHz via on-chip crystal oscillator and PLL, with programmable output data rates from 5.35 Hz to 105 Hz via 8-bit filter register (SF × 8 decimation).

It integrates rail-to-rail input buffering, selectable reference inputs (REFIN1/REFIN2), dual differential/pseudo-differential analog input configuration (up to 4 channels), and hardware-level 50/60 Hz notch rejection achieved through synchronized filter notches - not post-processing. The excitation current sources are ratioed, matched (±2.5% initial, ±20 ppm/°C drift matching), and switchable to IOUT1/IOUT2 outputs for V_BE or 4–20 mA loop sensing.

Key Specifications

Pinout & Package

The AD7709BRUZ is housed in a 24-lead TSSOP package (RU-24), with exposed pad for thermal performance. Pin assignments are fully validated per AD7709 Rev. A datasheet Figure 8 (Top View) and Pin Function Descriptions (pp. 9–10).

Key Features

Applications

Equivalent & Alternatives

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

Compared with AD7709BRUZ, AD7190BRUZ offers higher resolution but requires external excitation and switching components, while ADS1248IPWR provides lower power and integration for portable use but lacks the AD7709BRUZ's simultaneous line-frequency rejection and dual-switch capability - making AD7709BRUZ uniquely balanced for cost-sensitive, noise-immune industrial transmitters.

Availability

AD7709BRUZ is available at Aetrix Electronics and suitable for temperature measurement, pressure transducer interface, weigh scale load cell digitization, and 4–20 mA smart transmitter designs requiring stable component supply, long-lifecycle assurance, and traceable sourcing.

Supply support for AD7709BRUZ 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, with design and manufacturing expertise spanning precision data conversion, power management, and RF technologies.

The AD7709BRUZ belongs to Analog Devices' precision sigma-delta ADC product line, engineered specifically for low-frequency industrial sensor signal conditioning - emphasizing ratiometric accuracy, line-frequency immunity, and system-level integration to reduce external component count in field instrumentation.

FAQ

What is the maximum update rate of the AD7709BRUZ, and how is it configured?

The AD7709BRUZ supports a maximum update rate of 105 Hz, achieved by programming the filter register (SF) to 13. This value sets the Sinc³ decimation factor to 104 (13 × 8), yielding an output data rate of f_MOD/(SF × 8 × 3) = 32.768 kHz/(13 × 8 × 3) ≈ 105 Hz. The AD7709BRUZ update rate is fully software-configurable via the 8-bit SF word, with increments of 0.732 ms per step - allowing precise optimization for noise vs. speed trade-offs in each AD7709BRUZ application.

Does the AD7709BRUZ support true 16-bit resolution across all input ranges?

Yes - the AD7709BRUZ guarantees 16-bit no-missing-codes performance across its full operating range. At the ±2.56 V input range and 20 Hz update rate, it achieves 16-bit peak-to-peak (p-p) resolution, meaning it resolves 1 LSB = 78.125 µV. At the ±20 mV range and same update rate, p-p resolution is 13 bits (1 LSB = 2.44 µV), optimized for microvolt-level signals like thermocouples. Both specifications are tested and guaranteed per AD7709 Rev. A datasheet Table I.

How do the excitation current sources in the AD7709BRUZ differ from standard DAC-based current sources?

The AD7709BRUZ excitation current sources (IEXC1, IEXC2, IEXC3) are ratioed, laser-trimmed, and matched - not DAC-derived. They deliver 200 µA (IEXC1/IEXC2) and 25 µA (IEXC3) with ±10% initial tolerance, ±2.5% matching between IEXC1/IEXC2, and ±20 ppm/°C drift matching. This ratioed architecture ensures that current variations track reference voltage changes, preserving ratiometric accuracy in RTD measurements - a key advantage over standalone DAC-based solutions where current and reference drift independently.

Can the AD7709BRUZ operate from a 3.3 V supply, and what are the implications for power consumption?

Yes - the AD7709BRUZ is fully specified for 2.7 V to 3.6 V operation, making 3.3 V a valid and commonly used supply. At 3 V, typical supply current is 1.25 mA in normal mode (3.75 mW power dissipation) and 7 µA in power-down mode (with crystal running). The device maintains full specification compliance across this range, including 100 dB 50/60 Hz rejection and 16-bit linearity. This enables direct integration into 3.3 V microcontroller-based systems without level-shifting or additional regulators.

What is the function of the P1/SW1 and P2/SW2 pins on the AD7709BRUZ, and how are they controlled?

P1/SW1 and P2/SW2 are dual-function pins on the AD7709BRUZ: each can be configured either as a general-purpose digital output bit (P1/P2) or as a low-side power switch (SW1/SW2) connecting to PWRGND. Control is performed via the 4-bit I/O port register - writing '1' to the corresponding bit enables the switch (R_ON = 3 Ω typ @ 5 V), while '0' disables it. These pins support 20 mA continuous current and are commonly used to drive indicator LEDs, small relays, or heater elements - eliminating the need for external MOSFET drivers in compact AD7709BRUZ-based designs.