Analog Devices Inc. AD7707BRU

Overview

AD7707BRU from Analog Devices is a 3-channel, 16-bit sigma-delta ADC optimized for low-frequency precision measurement. It integrates programmable gain amplification (1–128), on-chip digital filtering with configurable notch frequency, and dual input ranges: ±10 mV to ±2.5 V (low-level) and ±10 V (high-level). It operates from single 2.7–3.3 V or 4.75–5.25 V supply and delivers <1 mW power dissipation at 3 V - ideal for battery-powered industrial sensor interfaces.

For engineers reviewing the AD7707BRU datasheet, AD7707BRU pinout, AD7707BRU application, or AD7707BRU equivalent, key selection criteria include its true bipolar ±100 mV capability on low-level inputs, ±0.003% integral nonlinearity, 3-wire SPI/QSPI/MICROWIRE-compatible serial interface, and integrated self- and system-calibration for offset/gain error removal in embedded data acquisition systems.

Technical Context

The AD7707BRU employs a charge-balancing sigma-delta modulator architecture with an on-chip digital filter whose first notch is software-programmable to adjust cutoff frequency and output update rate. Its analog front end includes a programmable gain amplifier (PGA) and supports buffered/unbuffered operation via the BUF bit.

It features three distinct analog input paths: two pseudo-differential low-level channels (AIN1/AIN2) referenced to LCOM with ±100 mV true bipolar range at gain=16, and one high-level channel (AIN3) referenced to HICOM accepting ±10 V directly - enabled by internal thin-film resistor networks eliminating external charge pumps or split supplies.

Key Specifications

Pinout & Package

The AD7707BRU is housed in a 20-lead TSSOP package (body width 4.4 mm, lead pitch 0.65 mm), pin-compatible with the SOIC variant but offering lower profile and improved thermal performance for dense layouts.

Key Features

Applications

Equivalent & Alternatives

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

Compared with AD7714BRU and ADS1248IPWR, the AD7707BRU uniquely balances 16-bit precision, integrated ±10 V input capability, sub-1 mW power, and on-chip calibration - making it the optimal choice for cost-sensitive, space-constrained industrial DAQ modules requiring multi-range analog signal conditioning.

Availability

AD7707BRU is available at Aetrix Electronics and suitable for pressure measurement, thermocouple monitoring, and RTD-based temperature control requiring stable component supply across extended industrial temperature ranges (−40°C to +85°C).

Supply support for AD7707BRU 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, serving industrial, automotive, communications, and healthcare markets since 1965.

The AD7707BRU belongs to Analog Devices' precision sigma-delta ADC product line, designed specifically for low-frequency, high-accuracy measurement in smart sensors, PLC analog input modules, and portable test equipment.

FAQ

What is the maximum input voltage range supported by the AD7707BRU on its high-level channel?

The AD7707BRU supports a ±10 V input range on its AIN3 high-level analog input channel. This is achieved using internal thin-film resistor networks that scale the input to the internal converter range without requiring external charge pumps or split supplies. The specification is guaranteed across the full operating temperature range (−40°C to +85°C) and applies when referenced to HICOM.

Does the AD7707BRU require external calibration components to achieve its specified accuracy?

No, the AD7707BRU does not require external calibration components. It includes on-chip self-calibration and system calibration capabilities that eliminate zero-scale and full-scale errors. Self-calibration corrects internal gain and offset errors, while system calibration compensates for errors introduced by external circuitry such as sensor bridges or reference dividers - all executed via the serial interface without additional hardware.

Can the AD7707BRU interface directly with a 3.3 V microcontroller SPI port?

Yes, the AD7707BRU supports direct interface with 3.3 V microcontrollers. Its digital I/Os (DIN, DOUT, SCLK, CS, DRDY) are fully compatible with 3.3 V logic levels: VINH is 2.0 V min and VINL is 0.4 V max at DVDD = 3 V, and the SCLK input includes a Schmitt trigger for noise immunity. No level-shifting circuitry is needed when DVDD = 3.3 V.

What is the significance of the BUF bit in the AD7707BRU setup register?

Setting the BUF bit in the AD7707BRU setup register enables internal buffering of the low-level analog inputs (AIN1/AIN2), increasing input impedance from ~1 GΩ (unbuffered) to >100 MΩ and reducing input current to <1 nA. This is essential when measuring high-impedance sources like thermocouples or unbuffered sensor bridges, preventing loading-induced measurement errors and improving common-mode rejection.

How does the AD7707BRU handle 50 Hz and 60 Hz power-line interference?

The AD7707BRU uses a programmable digital filter with configurable notch frequencies. When configured for 50 Hz or 60 Hz notch (e.g., 10 Hz/25 Hz/50 Hz or 10 Hz/20 Hz/60 Hz), it achieves ≥98 dB normal-mode rejection and ≥150 dB common-mode rejection at those frequencies - effectively suppressing line-frequency noise without external analog filters or synchronous sampling constraints.