Analog Devices Inc. EVAL-AD7705EBZ

Overview

EVAL-AD7705EBZ from Analog Devices is a full-featured evaluation board designed to interface with and characterize the AD7705 16-bit sigma-delta ADC. It supports 3V/5V operation, provides on-board 2.5V (AD780) and 1.23V (AD589) precision references, integrates a 4.9152 MHz crystal clock source, and enables direct analog signal acquisition via SMB connectors for AIN1±/AIN2± inputs in low-frequency measurement applications.

For engineers reviewing the EVAL-AD7705EBZ datasheet, EVAL-AD7705EBZ pinout, EVAL-AD7705EBZ application, or EVAL-AD7705EBZ equivalent, this board delivers rapid prototyping capability for sensor signal conditioning, industrial process monitoring, and precision weigh-scale front ends - with configurable reference, clock, and input routing via eight jumper links and dual PC interfaces (9-pin D-sub and 36-pin Centronics).

Technical Context

The EVAL-AD7705EBZ implements a complete hardware test environment for the AD7705, featuring buffered serial interface signals (SCLK, DIN, DOUT, CS, DRDY, RESET), decoupled analog (AVDD/AGND) and digital (DVDD/DGND) power domains, and user-configurable analog input paths through SKT3–SKT6 SMB sockets. All digital I/O lines are level-shifted and isolated using 74HC4050, 74C08, and 74HC244 buffers.

It supports both internal (on-board 4.9152 MHz crystal) and external clock sources via SKT11, dual reference selection (AD780 or AD589) via LK2, and flexible REFIN(±) sourcing via LK3/LK4 - enabling validation of unipolar/bipolar, buffered/unbuffered, and gain-adjusted configurations per the AD7705's setup register settings.

Key Specifications

Availability

EVAL-AD7705EBZ is available at Aetrix Electronics and suitable for industrial sensor interface development, precision instrumentation prototyping, and embedded ADC qualification requiring stable component supply and documented reference design support.

Supply support for EVAL-AD7705EBZ 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 semiconductor company specializing in high-performance analog, mixed-signal, and digital signal processing technologies for precision measurement and control systems.

The EVAL-AD7705EBZ belongs to Analog Devices' evaluation platform product line, engineered to accelerate design-in of its sigma-delta ADCs in low-frequency, high-resolution applications such as weigh scales, temperature sensors, and industrial process controllers.

FAQ

What is the primary function of the EVAL-AD7705EBZ?

The EVAL-AD7705EBZ is an evaluation board specifically built to test, configure, and validate the AD7705 16-bit sigma-delta ADC. It provides all necessary power regulation, reference circuitry, clock generation, buffered serial interface, and analog input connectivity - allowing engineers to evaluate performance, verify register settings, and prototype signal chains without designing custom hardware. The EVAL-AD7705EBZ supports both 3V and 5V operation and includes PC software for real-time register access and data capture.

Which ADC does the EVAL-AD7705EBZ support, and is it compatible with the AD7706?

The EVAL-AD7705EBZ is designed for the AD7705 2-channel 16-bit sigma-delta ADC and shares mechanical and electrical compatibility with the AD7706 3-channel variant - both use identical pinouts, register maps, and interface protocols. The board documentation explicitly states "EVAL-AD7705EB/EVAL-AD7706EB" and includes configuration options (e.g., link settings, socket labeling) that accommodate either device. However, channel count differences mean full utilization of the AD7706's third input requires verification of jumper and software setup per the AD7706 datasheet.

How is the EVAL-AD7705EBZ powered, and what are the voltage requirements?

The EVAL-AD7705EBZ requires two independent power supplies: analog (AVDD/AGND) and digital (DVDD/DGND). AVDD must be either +3V or +5V DC applied via terminal block J2, powering the AD7705 core and on-board references. DVDD may be supplied via J1, SKT1 pin 8, or SKT2 pin 9 - also at +3V or +5V - to drive digital buffers (U3–U5). AGND and DGND are internally joined only at the AD7705 ground pin; external connection elsewhere is discouraged to prevent ground loops and noise coupling in sensitive measurements using the EVAL-AD7705EBZ.

What software is included with the EVAL-AD7705EBZ, and which operating systems does it support?

The EVAL-AD7705EBZ ships with Windows-based evaluation software distributed on a 3.5″ floppy disk, supporting Windows 3.1™ and Windows 95™ with ≥4 MB RAM. It communicates via the PC's parallel port (LPT1/LPT2/PRN) using a standard Centronics cable to SKT2. The software enables full register read/write, real-time data acquisition, noise analysis (RMS, peak-to-peak), graphing, histogram generation, and export to Excel or Mathcad - all targeting direct interaction with the AD7705 on the EVAL-AD7705EBZ board.

Can external clock and reference sources be used with the EVAL-AD7705EBZ?

Yes - the EVAL-AD7705EBZ supports external clock injection via SKT11 (BNC connector) when LK1 is set to position "A", and external reference voltages applied to SKT9 (REFIN−) and SKT10 (REFIN+) when LK3 and LK4 are configured accordingly. This allows validation of the AD7705 under non-standard clock frequencies (500 kHz to 5 MHz) or custom reference topologies - essential for system-level timing and accuracy testing beyond the default 4.9152 MHz crystal and AD780/AD589 references on the EVAL-AD7705EBZ.