Analog Devices Inc. EVAL-AD7797EBZ

Overview

EVAL-AD7797EBZ from Analog Devices is a USB-powered evaluation board designed exclusively for the AD7797 24-bit, low-power sigma-delta ADC targeting bridge sensor signal conditioning. It integrates an on-board ADP3303 3.3 V regulator, SMB analog input/reference connectors, and a Cypress CY7C68013A USB/SPI interface controller to enable direct PC-based configuration and data acquisition at update rates from 4.17 Hz to 123 Hz.

For engineers reviewing the EVAL-AD7797EBZ datasheet, EVAL-AD7797EBZ pinout, EVAL-AD7797EBZ application, or EVAL-AD7797EBZ equivalent, this board supports rapid validation of AD7797 performance in precision weigh-scale, pressure transducer, and strain-gauge measurement systems - with LabVIEW™-based software, real-time noise analysis, and configurable register-level control via USB.

Technical Context

The EVAL-AD7797EBZ implements a complete hardware interface between a host PC and the AD7797 ADC, using a dedicated CY7C68013A USB microcontroller to translate USB commands into SPI transactions. It provides selectable AVDD sourcing (USB 5 V, on-board 3.3 V, or external supply) and configurable reference routing (internal AVDD/2 or external SMB-connected REFIN±).

Board-level features include five user-configurable jumpers (LK1–LK5) for input biasing, reference selection, and power source routing, plus five SMB connectors (AIN+, AIN−, REFIN+, REFIN−, CLK) and an 8-pin prototype header (J2) - all supporting differential bridge sensor signal injection, simultaneous 50/60 Hz rejection, and rms noise as low as 65 nV at 4.17 Hz update rate.

Key Specifications

Availability

EVAL-AD7797EBZ is available at Aetrix Electronics and suitable for precision sensor evaluation, industrial calibration system development, and bridge-based transducer prototyping requiring stable component supply and traceable evaluation hardware.

Supply support for EVAL-AD7797EBZ 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 EVAL-AD7797EBZ belongs to Analog Devices' precision data acquisition evaluation platform family, engineered to accelerate design-in of low-noise, low-power sigma-delta ADCs in sensor front-end applications where resolution, drift, and EMI immunity are critical.

FAQ

What is the primary function of the EVAL-AD7797EBZ?

The EVAL-AD7797EBZ is a dedicated evaluation board that enables full functional and performance characterization of the AD7797 24-bit sigma-delta ADC. It provides USB-based communication, configurable analog signal routing, on-board regulation, and Windows-compatible software - allowing engineers to validate bridge sensor signal chain behavior without custom hardware. The EVAL-AD7797EBZ does not operate standalone; it requires connection to a PC and installation of Analog Devices' evaluation software to configure registers and acquire conversion data.

Does the EVAL-AD7797EBZ require an external power supply?

No - the EVAL-AD7797EBZ is fully powered via the USB Mini-B connector (J1), delivering 5 V to both the board logic and the AD7797 when configured appropriately. An external 3 V or 5 V supply can be applied via terminal block J3 only if needed for specific test conditions, such as evaluating supply sensitivity or bypassing the on-board ADP3303 regulator. Default operation uses USB power exclusively, eliminating need for auxiliary supplies during standard evaluation.

How do I configure the AD7797's update rate and input channel on the EVAL-AD7797EBZ?

Update rate and input channel selection are performed through the included Windows evaluation software: use the "Quick Analysis" window for basic settings (e.g., 16.7 Hz default, AIN+–AIN−), or open the "Registers" window to directly modify the Mode Register bits controlling clock source, output rate, and channel selection. All register writes are executed over USB→SPI and take effect immediately. The EVAL-AD7797EBZ firmware ensures bit-perfect register mapping to the AD7797's documented control space.

Can the EVAL-AD7797EBZ be used with sensors other than bridge types?

Yes - while optimized for ratiometric bridge sensors (e.g., load cells, pressure bridges), the EVAL-AD7797EBZ supports any differential or pseudo-differential analog source within the AD7797's input range of ±VREF/128. Its SMB connectors accept signals up to ±25.8 mV (with 3.3 V reference), and jumper LK1/LK2 allow mid-supply biasing for single-ended sources. However, the board lacks excitation circuitry - external bridge excitation must be supplied separately, and noise performance remains tied to the AD7797's native 65 nV rms specification at 4.17 Hz.

Is the EVAL-AD7797EBZ RoHS compliant and production-ready?

Yes - the EVAL-AD7797EBZ is RoHS compliant (denoted by the "Z" suffix in EVAL-AD7797EBZ1) and shipped with full documentation, schematic, and BOM. However, it is explicitly designated for evaluation only: Analog Devices states it is "not intended for production purposes" and carries no warranties for field deployment. Its layout and components reflect reference design intent, not industrial reliability certification - so while suitable for lab validation and proof-of-concept, it must not be deployed in life-support devices or final end-equipment without redesign and qualification.