Analog Devices Inc. EVAL-AD7781EBZ

Overview

EVAL-AD7781EBZ from Analog Devices is a fully featured USB-powered evaluation board for the AD7781 20-bit, pin-programmable, low-power sigma-delta ADC. It supports bridge sensor interfacing via a 6-pin load cell terminal (J4), provides dual output data rates (10 Hz / 16.7 Hz), offers programmable gain (1 or 128), delivers 44 nV rms noise at 10 Hz/128 gain, and integrates an on-board ADP3303 3.3 V regulator and CY7C68013A USB controller for standalone PC communication.

For engineers reviewing the EVAL-AD7781EBZ datasheet, EVAL-AD7781EBZ pinout, EVAL-AD7781EBZ application, or EVAL-AD7781EBZ equivalent, this board enables rapid functional validation of the AD7781 in precision weighscale, strain gauge, and low-frequency industrial sensor systems - with LabVIEW-based software, SMB analog input connectors, configurable link settings, and full schematic documentation included.

Technical Context

The EVAL-AD7781EBZ implements a complete hardware interface between a host PC and the AD7781 ADC using a Cypress CY7C68013A USB microcontroller operating in slave FIFO mode, communicating over SPI. Power is sourced from USB (5 V) or optionally from external 3 V/5 V supplies via J2, regulated to 3.3 V by the ADP3303 for AVDD and digital logic.

Board configuration is managed through 16 user-accessible jumpers (LK1–LK16): LK15 selects output data rate (10 Hz or 16.7 Hz), LK16 sets gain (1 or 128), LK5 chooses AVDD source, and LK12–LK14 configure bridge power-down switching for load cell bias control - enabling precise TARE and full-scale calibration in weighscale demos.

Key Specifications

Availability

EVAL-AD7781EBZ is available at Aetrix Electronics and suitable for precision weighscale development, bridge-based sensor prototyping, and low-frequency industrial measurement applications requiring stable component supply, traceable sourcing, and long-term evaluation platform continuity.

Supply support for EVAL-AD7781EBZ 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 sensor signal conditioning.

The EVAL-AD7781EBZ belongs to Analog Devices' precision ADC evaluation platform family, engineered specifically to accelerate development of high-resolution, low-power measurement systems for industrial weighing, structural monitoring, and sensor transducer interfaces.

FAQ

What is the primary function of the EVAL-AD7781EBZ?

The EVAL-AD7781EBZ is a dedicated evaluation board designed to demonstrate and validate the operation of the AD7781 20-bit sigma-delta ADC. It provides full hardware and software support-including USB interface, configurable gain/data rate links, SMB analog inputs, and load cell terminal J4-to enable rapid testing of the AD7781 in low-frequency precision measurement applications without custom PCB design. The EVAL-AD7781EBZ integrates all necessary power regulation, signal conditioning, and host communication resources.

Does the EVAL-AD7781EBZ require an external power supply?

No - the EVAL-AD7781EBZ is fully powered via the USB Mini-B connector (J1), delivering 5 V to the board. An onboard ADP3303 regulator generates a clean 3.3 V supply for the AD7781 and digital circuitry. However, an optional external 3 V or 5 V supply can be connected via terminal block J2 if isolation or alternative power routing is required during system-level validation. USB power remains sufficient for all standard evaluation use cases of the EVAL-AD7781EBZ.

How is the AD7781's output data rate configured on the EVAL-AD7781EBZ?

The output data rate of the AD7781 on the EVAL-AD7781EBZ is set using jumper LK15: Position "10 Hz" configures the ADC for 10 Hz output (with 44 nV rms noise at gain 128), while Position "16.7 Hz" selects 16.7 Hz operation. Both rates provide simultaneous 50 Hz and 60 Hz notch rejection. This hardware-based selection ensures deterministic timing behavior and eliminates firmware dependencies - a key feature confirmed in UG-079 for reliable noise-sensitive measurements using the EVAL-AD7781EBZ.

Can the EVAL-AD7781EBZ interface directly with a load cell?

Yes - the EVAL-AD7781EBZ includes a dedicated 6-pin terminal block (J4) for direct connection of 4-wire or 6-wire load cells. Jumpers LK13 and LK14 configure bridge excitation and power-down switching, while REFIN(−) must be shorted to the GND/PSW terminal on J4 to activate load cell bias control. The included weighscale demo software performs zero-scale and full-scale calibration, making the EVAL-AD7781EBZ a turnkey solution for load cell characterization and prototype validation.

Is PC software provided with the EVAL-AD7781EBZ?

Yes - the EVAL-AD7781EBZ ships with Windows-compatible evaluation software on CD (also available from Analog Devices' website). The software provides real-time control of the AD7781 via USB, including adjustable sampling, noise analysis, waveform/histogram visualization, voltage/code display, and Excel/MathCAD export. It includes a dedicated weighscale demo window with TARE calibration, full-scale weight entry, and live gain/output rate monitoring - all verified and documented in UG-079 for the EVAL-AD7781EBZ.