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This version (15 Dec 2017 22:49) was approved by Brandon.The Previously approved version (04 Dec 2017 09:34) is available.Diff

CN0225 Evaluation Board Guide

Overview

CN0225 is a complete analog front end for digitizing ±10 V industrial level signals with a 16-bit differential input PulSAR® ADC. The circuit provides a high impedance instrumentation amplifier input with high CMR, level shifting, attenuation, and differential conversion, with only two analog components.The two active components which drive an AD7687 differential input 16-bit PulSAR ADC are the AD8295 precision instrumentation amplifier and the AD8275 level translator/ADC driver. An ADR431 low noise 2.5V XFET® reference supplies the voltage reference for the ADC.

The AD8295 has two uncommited on-chip signal procesing amplifiers and two precisely matched 20 kΩ resistors in a small 4 mm X 4 mm package.

The AD8275 is a G = 0.2 difference amplifier that can be used to attenuate ±10 V industrial signals, and the attenuated signal can be easily interfaced to a single supply low voltage ADC. The AD8275 performs the attenuation and level shifting function in the circuit, maintaining good CMR without any need for external components.

The CN0225 needs +15 V, -15 V and +6 V power supply inputs and thus, needs a triple output DC power supply. The board also connects to ADI's System Demonstration Platform (*SDP*).


Required Equipment


General Setup

Block Assignments

  • The EVAL-CN0225-SDPZ (CN0225 Board) connects to the EVAL-SDP-CB1Z (SDP-B Board) via the 120-Pin Connector (SDP Conn)
  • The EVAL-SDP-CB1Z (SDP-B Board) connects to the PC via the USB cable
  • Terminal block J1 is the +/- analog signal input
  • Terminal block J2 is the +6 V power supply input
  • Terminal block J3 is the +/- 15 V power supply input
  • Terminal block J4 contains the test points for the SPI signals

Connect the (EVAL-CN0225-SDPZ) and the (SDP-B Board), then power the (EVAL-CN0225-SDPZ) through the triple output power supply before connecting the (SDP-B Board) to the PC

Setup Block Diagram

Jumper Settings

See the table in the image below for the jumper settings. Values in red are the default settings for the EVAL-CN0225-SDPZ


Installing the Evaluation Software

  1. Extract the file CN0225 Evaluation Software and open setup.exe

    NOTE: It is recommended that you install the CN0203 Evaluation Software to the default directory path C:\Program Files (x86)\Analog Devices\ and all National Instruments products to C:\Program Files\National Instruments\


  2. Press Next to view the National Instruments Software License Agreement
  3. Select the option which accepts the License Agreement and press Next to view the installation review page
  4. Press Next to start the installation
  5. Upon completion of the installation of the CN0225 Evaluation Software, the installer for the ADI SDP Drivers will execute

    NOTE: It is recommended that you close all other applications before clicking “Next”. This will make it possible to update relevant system files without having to reboot your computer.


  6. Press “Next” to set the installation location for the SDP Drivers

    It is recommended that you install the drivers to the default directory path
    C:\Program Files\Analog Devices\SDP\Drivers


  7. Press “Next” to install the SDP Drivers. When prompted by Windows Security, just press Install
  8. Press Finish to complete the installation
  9. (Optional) Restart the PC when prompted by the installer

Using the Evaluation Software

Main Window

  1. Board Connection Control Section
  2. Data Acquisition Control Section
    • connector Select
      • Selects which 120-pin connection of the SDP-B Board to use
    • Fs (Hz) Field
      • Sets the sampling frequency of the CN0225 ADC
    • Samples Field
      • Sets the number of samples the CN0225 ADC takes
    • SCLK (Hz) Field
      • Sets the SPI clock frequency used by the evaluation board
    • Acquire Samples Button
      • Commands the CN0225 ADC to sample at the set sampling frequency and read the set number of samples
    • Save Data to File Button
      • Saves the current sample readings to an output file
  3. Activity Frame
    • Time Domain Tab
      • Displays the measured ADC sample values vs time plot
    • Frequency Domain Tab
      • Plots the FFT of the the ADC samples with the amplitudse in dB of the full scale ADC value

  • Histogram
    • Plots the number of occurrences of ADC sample values

  • S/W Version Info
    • Shows the software and hardware versions, vendor and product IDs
    • Flash LED Button tests the SDP communication to the CN0225
    • Read Firmware Button reads the current SDP firmware for debugging

Running the System

  1. Open the CN0225.exe application from the default installation location.
  2. Set the correct connector and SCLK settings for the board in the Data Acquisition Control
  3. Click the Connect Button
  4. Set the desired sampling frequency in Hz and the number of samples to read
  5. Click Acquire Samples Button
  6. Click the Time Domain Tab to view the ADC sample values vs time plot
  7. Click the Frequency Domain Tab to view the FFT plot of the sample values
  8. Click the Histogram Tab to view the number of occurrences of ADC sample values
  9. Click the S/W Version Info Tab to view the hardware and software versions
  10. Click Save Data to File Button if you want to save the current sample readings
  11. Click the Disconnect Button if finished
  12. Click the STOP APP Button to exit the software

Schematic, PCB Layout, Bill of Materials

EVAL-CN0225-SDPZ Design & Integration Files

  • Schematics
  • PCB Layout
  • Bill of Materials
  • PADS project

End of Document

resources/eval/user-guides/circuits-from-the-lab/cn0225.txt · Last modified: 15 Dec 2017 22:49 by Brandon