Analog Devices Inc. AD7706BRU

Overview

AD7706BRU from Analog Devices is a 16-bit sigma-delta analog-to-digital converter with three pseudo-differential input channels, programmable gain (1–128), 0.003% integral nonlinearity, and 1 mW max power dissipation at 3 V - designed for precision low-frequency measurement in sensor signal chains such as pressure and temperature transducers.

For engineers reviewing the AD7706BRU datasheet, AD7706BRU pinout, AD7706BRU application, or AD7706BRU equivalent, key selection criteria include its 3-wire SPI-compatible serial interface, bipolar/unipolar input support up to ±2.5 V (5 V supply) or ±1.225 V (3 V supply), on-chip calibration, and compatibility with microcontroller- or DSP-based data acquisition systems.

Technical Context

The AD7706BRU employs a charge-balancing sigma-delta modulator followed by an on-chip digital filter with programmable first-notch frequency, enabling configurable output update rates and high rejection of 50 Hz/60 Hz line interference. Its analog front end integrates a programmable-gain amplifier (PGA) and optional input buffer, supporting direct connection to low-level transducer outputs without external signal conditioning.

It operates from a single 2.7–3.3 V or 4.75–5.25 V supply, features differential reference inputs, and delivers 16-bit no-missing-codes performance with <600 nV rms noise. The device supports self-calibration and system calibration to eliminate offset and gain errors across temperature.

Key Specifications

Pinout & Package

AD7706BRU is available in a 16-lead TSSOP package (thin shrink small outline), measuring 5 mm × 4.4 mm × 1.2 mm, with 0.65 mm lead pitch and exposed pad for thermal enhancement.

Key Features

Applications

Equivalent & Alternatives

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

Compared with AD7705BRU, the AD7706BRU adds a third pseudo-differential channel and COMMON reference architecture for simplified multi-sensor layout, while ADS1115IDGSR trades programmable digital filtering and Schmitt-triggered SPI for I²C convenience and lower quiescent current - making AD7706BRU optimal for noise-critical, SPI-based industrial sensor nodes requiring three synchronized measurements.

Availability

AD7706BRU is available at Aetrix Electronics and suitable for pressure measurement, temperature monitoring, and smart transmitter applications requiring stable component supply, long-term lifecycle support, and traceable sourcing for industrial OEM programs.

Supply support for AD7706BRU 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 AD7706BRU belongs to Analog Devices' precision sigma-delta ADC product line, engineered specifically for low-frequency, high-resolution sensor signal acquisition in industrial, instrumentation, and process control systems.

FAQ

What is the maximum input voltage range supported by the AD7706BRU?

The AD7706BRU supports unipolar input ranges from 0 mV to VREF/gain and bipolar ranges of ±VREF/gain. With a 2.5 V reference and gain = 1, it accepts ±2.5 V differential inputs referenced to COMMON; with a 1.225 V reference and gain = 1, it handles ±1.225 V. Absolute input voltages must stay within GND −100 mV to VDD +30 mV for specified performance. This range enables direct connection to most industrial transducers without level-shifting circuitry.

Does the AD7706BRU require an external reference voltage?

Yes, the AD7706BRU requires an external differential reference voltage applied between REF IN(+) and REF IN(−). For optimal performance, use 2.5 V ±1% with a 5 V supply or 1.225 V ±1% with a 3 V supply. The device does not include an internal reference; however, its high PSRR (>90 dB) and programmable gain allow stable operation even with moderately noisy or drifting references when combined with on-chip calibration.

How does the AD7706BRU handle 50 Hz and 60 Hz interference?

The AD7706BRU uses a programmable digital filter with adjustable first-notch frequency to provide >98 dB rejection at 50 Hz or 60 Hz. By configuring the filter notch to match local mains frequency (e.g., 50 Hz in Europe, 60 Hz in North America), the device achieves high common-mode and normal-mode rejection without external notch filters. This feature is especially valuable in factory-floor or utility-metering applications where line-frequency noise dominates sensor signals.

Can the AD7706BRU operate from a 3.3 V supply?

Yes, the AD7706BRU is fully specified for operation from 2.7 V to 3.3 V. At 3 V, it supports a 1.225 V reference, delivers 1 mW max power dissipation, and maintains 16-bit no-missing-codes performance. Standby current drops to 8 μA, making it ideal for battery-powered instrumentation. All logic levels, timing parameters, and analog specifications remain valid across this supply range without derating.

What is the function of the COMMON pin on the AD7706BRU?

The COMMON pin serves as the shared negative reference for all three pseudo-differential analog inputs (AIN1, AIN2, AIN3) on the AD7706BRU. Unlike the AD7705's fully differential architecture, this pin simplifies PCB layout by eliminating separate AIN(−) traces per channel. It enables simultaneous sampling of multiple sensors referenced to a common point - essential for multi-transducer systems like multi-point pressure arrays or multi-zone temperature monitoring.