EVAL-AD7902SDZ User Guide UG-608 One Technology Way • P.O. Box 9106 • Norwood, MA 02062-9106, U.S.A. • Tel: 781.329.4700 • Fax: 781.461.3113 • www.analog.com Evaluating the AD7902 Dual Pseudo Differential, 16-Bit, 1 MSPS PulSAR ADC FEATURES ADDITIONAL EQUIPMENT/SOFTWARE NEEDED Full featured evaluation board for the AD7902 Versatile analog signal conditioning circuitry On-board reference, reference buffers, and ADC drivers System demonstration board compatible (EVAL-SDP-CB1Z) PC software for control and data analysis of time and frequency domain System demonstration platform (EVAL-SDP-CB1Z) Precision analog signal source Power supply, +7 V/−2.5 V (optional) USB cable SMA cable PC running Windows XP SP2, Windows Vista, Windows 7, or higher with USB 2.0 port Evaluation software for the AD7902 (download from AD7902 product page) EVALUATION KIT CONTENTS EVAL-AD7902SDZ evaluation board Wall power supply 9 V dc adapter Daughter card power connector ONLINE RESOURCES Documents Needed AD7902 data sheet EVAL-AD7902SDZ user guide Required Software EVAL-AD7902SDZ evaluation software FAQs and Troubleshooting TYPICAL SETUP SMA CONNECTOR SIGNAL SOURCE 11798-001 PC Figure 1. Typical Setup for the EVAL-AD7902SDZ (EVAL-AD7902SDZ on Left and EVAL-SDP-CB1Z on Right) PLEASE SEE THE LAST PAGE FOR AN IMPORTANT WARNING AND LEGAL TERMS AND CONDITIONS. Rev. 0 | Page 1 of 32 UG-608 EVAL-AD7902SDZ User Guide TABLE OF CONTENTS Features .............................................................................................. 1 Modes of Operation ....................................................................... 12 Evaluation Kit Contents ................................................................... 1 SDP Controlled Mode ............................................................... 12 Additional Equipment/Software Needed ...................................... 1 Standalone Mode ........................................................................ 12 Online Resources .............................................................................. 1 How to Use the Software ............................................................... 13 Typical Setup ..................................................................................... 1 Revision History ............................................................................... 2 Setting Up the System for Data Capture: Board Operation/Connection Sequence ................................. 13 General Description ......................................................................... 3 Starting the Software .................................................................. 13 Getting Started .................................................................................. 4 Overview of the Main Window ................................................ 15 Software Installation Procedures ................................................ 4 Generating a Waveform Analysis Report................................ 16 Evaluation Board Setup Procedures........................................... 7 Generating a Histogram of the ADC Code Distribution ..... 17 Evaluation Board Hardware ............................................................ 8 Generating a Fast Fourier Transform of AC Characteristics ...... 18 Device Description ....................................................................... 8 Generating a Summary of the Waveform, Histogram, and Fast Fourier Transform .............................................................. 19 Power Supplies .............................................................................. 8 Link Configuration Options ......................................................... 10 Evaluation Board Circuitry ........................................................... 11 Analog Inputs .............................................................................. 11 Reference ..................................................................................... 11 Serial Interface ............................................................................ 11 Evaluation Board Schematics and Artwork ................................ 20 EVAL-AD7902SDZ Schematics ............................................... 20 EVAL-AD7902SDZ Layout ....................................................... 26 Bill of Materials ............................................................................... 29 Related Links ................................................................................... 31 REVISION HISTORY 2/14—Revision 0: Initial Version Rev. 0 | Page 2 of 32 EVAL-AD7902SDZ User Guide UG-608 GENERAL DESCRIPTION The EVAL-AD7902SDZ is an evaluation board designed to demonstrate the low power AD7902 performance and to provide an easy to understand interface for a variety of system applications. The AD7902 is a dual pseudo differential 16-bit, 1 MSPS PulSAR® ADC. A full description of the AD7902 is available in the AD7902 data sheet and should be consulted when using this evaluation board. The evaluation board is ideal for use with the Analog Devices, Inc., system demonstration platform (SDP) board, EVAL-SDP-CB1Z. The evaluation board interfaces to the SDP board via a 120-pin connector. SMA Connectors J6, J10, J14, and J15 are provided to connect a low noise analog signal source. The user PC software executable controls the evaluation board over the USB through the SDP board, EVAL-SDP-CB1Z. On-board components include the following: ADR435: high precision, buffered band gap 5.0 V reference AD8031: reference buffer ADA4841-1: signal conditioning circuit with op amps ADP7104 and ADP2301: regulators to derive necessary voltage levels on board Rev. 0 | Page 3 of 32 UG-608 EVAL-AD7902SDZ User Guide GETTING STARTED 4. SOFTWARE INSTALLATION PROCEDURES Download the evaluation board software from the AD7902 product page on the Analog Devices website, at www.analog.com. There are two parts to the installation: • • Select the location to install the software, and then click Next. (The default location is C:\Program Files (x86)\ Analog Devices\AD7902_03 Evaluation Software\. This location also contains the executable software and example files.) AD7902 evaluation board software installation EVAL-SDP-CB1Z system demonstration platform board drivers installation Warning Install the evaluation board software and drivers before connecting the evaluation board and EVAL-SDP-CB1Z board to the USB port of the PC to ensure that the evaluation system is correctly recognized when it is connected to the PC. Installing the AD7902 Evaluation Board Software To install the AD7902 evaluation board software, Figure 3. AD7902 Evaluation Board Software Installation: Selecting the Location for Software Installation (the Default Location Is Shown) 5. A license agreement appears. Read the agreement, and then select I accept the License Agreement and click Next. 11798-005 11798-003 2. 3. Start the Windows operating system and download the software from the AD7902 product page on the Analog Devices website, at www.analog.com. Unzip the downloaded file. Double-click the setup.exe file to begin the evaluation board software installation (see Figure 2). 11798-004 1. Figure 2. AD7902 Evaluation Board Software Installation: Installation Begins Figure 4. AD7902 Evaluation Board Software Installation: Accepting the License Agreement Rev. 0 | Page 4 of 32 EVAL-AD7902SDZ User Guide 8. The dialog box informs you when the installation is complete. Click Next. 11798-008 A summary of the installation is displayed. Click Next to continue. 11798-006 6. UG-608 Figure 7. AD7902 Evaluation Board Software Installation: Indicating When the Installation Is Complete Figure 5. AD7902 Evaluation Board Software Installation: Reviewing a Summary of the Installation 9. The setup for the installation of the EVAL-SDP-CB1Z system demonstration platform board drivers automatically begins to load. 11798-009 A dialog box shows the installation progress. Figure 8. Loading the Setup for SDP Drivers Installation Installing the EVAL-SDP-CB1Z System Demonstration Platform Board Drivers After the installation of the evaluation board software is complete, a welcome window is displayed for the installation of the EVALSDP-CB1Z system demonstration platform board drivers. 11798-007 1. Make sure that all other applications are closed, and then click Next. Figure 6. AD7902 Evaluation Board Software Installation: Displaying Installation Progress 11798-010 7. Figure 9. EVAL-SDP-CB1Z Drivers Setup: Beginning the Drivers Installation Rev. 0 | Page 5 of 32 UG-608 Select the location to install the drivers, and then click Install. 5. To complete the drivers installation, click Finish, which closes the installation wizard. 11798-014 11798-011 2. EVAL-AD7902SDZ User Guide Figure 10. EVAL-SDP-CB1Z Drivers Setup: Selecting the Location for Drivers Installation 3. Figure 13. EVAL-SDP-CB1Z Drivers Setup: Completing the Drivers Setup Wizard Installation of the SDP drivers begins. Before using the evaluation board, you must restart your computer. A dialog box opens, giving you the following options: Restart, Shut Down, Restart Later. Click the appropriate button. 11798-012 11798-015 6. Figure 11. EVAL-SDP-CB1Z Drivers Setup: Beginning the Installation A dialog box appears asking whether you would like to install this device software. Click Install to confirm that you would like to install the drivers. 11798-013 4. Figure 12. EVAL-SDP-CB1Z Drivers Setup: Granting Permission to Install Drivers Rev. 0 | Page 6 of 32 Figure 14. EVAL-SDP-CB1Z Drivers Setup: Restarting the Computer EVAL-AD7902SDZ User Guide UG-608 EVALUATION BOARD SETUP PROCEDURES Verifying the Board Connection The AD7902 evaluation board connects to the (EVAL-SDP-CB1Z) system demonstration board. The EVAL-SDP-CB1Z board is the controller board, which is the communication link between the PC and the main evaluation board. 1. Figure 1 shows a photograph of the connections made between the EVAL-AD7902SDZ daughter board and the EVAL-SDP-CB1Z motherboard. 2. Connecting the Evaluation and SDP Boards to a PC 2. 3. 4. Install the AD7902 software. Ensure that the EVAL-SDPCB1Z board is disconnected from the USB port of the PC while installing the software. The PC must be restarted after the installation is complete. Before connecting power, connect the 120-pin connector, J5, of the EVAL-AD7902SDZ board to Connector J4 on the EVAL-SDP-CB1Z board. Nylon screws are included in the EVAL-AD7902SDZ evaluation kit and can be used to ensure that the EVAL-AD7902SDZ and EVAL-SDP-CB1Z boards are connected firmly together. Connect the 9 V power supply adapter included in the kit to the EVAL-SDP-CB1Z. Connect the EVAL-SDP-CB1Z board to the PC via the USB cable. (If you are using Windows® XP, you may need to search for the EVAL-SDP-CB1Z drivers. Choose to automatically search for the drivers for the EVAL-SDP-CB1Z board if prompted by the operating system.) 11798-016 1. Allow the Found New Hardware Wizard to run after the EVAL-SDP-CB1Z board is plugged into your PC. (If you are using Windows XP, you may need to search for the EVAL-SDP-CB1Z drivers. Choose to automatically search for the drivers for the EVAL-SDP-CB1Z board if prompted by the operating system.) Check that the board is connected to the PC correctly using the Device Manager of the PC. a. Access the Device Manager as follows: i. Right-click My Computer and then click Manage. ii. A dialog box appears asking for permission to allow the program to make changes to your computer. Click Yes. iii. The Computer Management box appears. From the list of System Tools, click Device Manager. b. Under ADI Development Tools, Analog Devices System Development Platform SDP-B should appear (see Figure 15), indicating that the EVAL-SDP-CB1Z driver software is installed and that the board is connected to the PC correctly. Figure 15. Device Manager: Checking that the Board Is Connected to the PC Correctly Rev. 0 | Page 7 of 32 UG-608 EVAL-AD7902SDZ User Guide EVALUATION BOARD HARDWARE DEVICE DESCRIPTION The AD7902 is a 16-bit, 1 MSPS, precision, power efficient, dual pseudo differential PulSAR ADC that uses SAR-based architecture and does not exhibit any pipeline delay or latency. The AD7902 is specified for use with a single supply of 2.5 V (VDD1, VDD2). The interface from the digital host to the AD7902 uses 1.8 V/2.5 V/3.3 V/5.5 V logic. The AD7902 is compatible with the SPI/QSPI/MICROWIRE/DSP serial interface to transfer data conversions. Complete AD7902 specifications are provided in the AD7902 data sheet and should be consulted in conjunction with this user guide when using the evaluation board. Full details on the EVAL-SDPCB1Z are available on the Analog Devices website, at www.analog.com. Figure 26 to Figure 31 show the evaluation board schematics. The board consists of an AD7902 ADC (U1) with a reference (U6—ADR435), and two ADC drivers (U12 and U17— ADA4841-1YRZ). The evaluation board is a flexible design that enables you to adjust compensation components and operate the evaluation board from an adjustable bench top power supply. Each on-board power supply is decoupled where it enters the board as well as where it connects to each device. A single ground plane is used on this board to minimize the effect of high frequency noise interference. Alternatively, the board can be powered from a bench top power supply by using the J2 and J3 screw terminals and changing the SL1 to SL4 and LK3 to LK5 solder link settings to Position B (see Table 2). When bench top power is used, use of the wall adapter and the on-board power supplies are no longer required. Table 2. Solder Links—Settings for Bench Top Power Supply1 Link SL1 SL2 SL3 SL4 LK3 LK4 LK5 1 The evaluation board can be powered from a wall adapter or from a bench top power supply. By default, the board is set up to operate from a 9 V wall adapter using the on-board power supplies described in Table 1. Table 1. Power Supplies Provided on the Board Function SDP power Positive rail Negative rail ADC VDD rail VDRIVE (digital power) Function +VS −VS −VS +VS V_SDP VREF VDD for ADC All other solder link settings are as described in Table 3. POWER SUPPLIES Power Supply (V) +5 +7.5 −2.5 +2.5 +3.3 Setting B B B B B B B Components Used ADP2301 ADP7104 ADP2301 ADP7104 ADP7104 Rev. 0 | Page 8 of 32 EVAL-AD7902SDZ User Guide UG-608 VIN = 9V WALL ADAPTER (OPTIONAL) –VS POWER SUPPLY CIRCUITRY ADP7104, ADP2301 GND +VS +7.5V/–2.5V +7.5V 2.5V 3.3V +5V (OPTIONAL) +5V ADR435 VDD GND VCM VSDP 5V AD8031 ADSP-BF527 DSP +7.5V ADA4841-1 VIN1+ VDD1 REF1 VIO1 SDI1 IN1+ SCK1 ADC1 SDO1 IN1– GND CNV1 –2.5V ADA4841-1 +7.5V VIN1– GLUE LOGIC A B –2.5V 2.5V 5V SPORT +7.5V VDD2 REF2 VIO2 SDI2 IN2+ SCK2 ADC2 SDO2 IN2– GND CNV2 VIN2+ –2.5V ADA4841-1 +7.5V VIN2– GLUE LOGIC A B –2.5V AD7902/AD7903 PulSAR EVALUATION BOARD SDP BOARD Figure 16. Simplified Evaluation Board Functional Block Diagram Rev. 0 | Page 9 of 32 11798-002 ADA4841-1 UG-608 EVAL-AD7902SDZ User Guide LINK CONFIGURATION OPTIONS Care should be taken before applying power and signals to the evaluation board to ensure that all link positions are as required by the operating mode. There are two modes in which to operate the evaluation board. The evaluation board can be operated in SDP controlled mode to be used with the SDP board, or the evaluation board can be used in standalone mode. When operating in SDP controlled mode, ensure that VIO is 3.3 V. Operating with a VIO greater than 3.3 V in SDP controlled mode may damage the SDP board. The Setting column of Table 3 shows the default positions in which the links are set when the evaluation board is packaged. When the board is shipped, it is assumed that you are going to operate the evaluation board with the SDP board (SDP controlled mode). Table 3. Solder Links—Factory Default Settings Link SL1 SL2 SL3 SL4 SL5 SL6 LK1 LK2 LK3 LK4 LK5 LK6 LK7 LK8 LK9 LK10 LK11 LK12 Setting A A A A B B A A A A A Not applicable Not applicable A A A A A Function +VS −VS −VS +VS Analog input Analog input +VS −VS V_SDP VREF VDD for ADC Not applicable Not applicable ADC2 input ADC2 input U17 input U17 input ADC2 input Comment Change to B if using bench supplies. Change to B if using bench supplies. Change to B if using bench supplies. Change to B if using bench supplies. Do not alter. Do not alter. Change to B if using bench supplies. Change to B if using bench supplies. Change to B if using bench supplies. Change to B if using bench supplies. Change to B if using bench supplies. Do not place Do not place Do not alter. Change to B if using ADC1 input. Change to B if U17 needs to be bypassed. Change to B if U17 needs to be bypassed. Do not alter. Rev. 0 | Page 10 of 32 EVAL-AD7902SDZ User Guide UG-608 EVALUATION BOARD CIRCUITRY ANALOG INPUTS The analog inputs to the evaluation board are SMA Connectors J6 and J14. These inputs are buffered with dedicated amplifier circuitry (U12 and U17), as shown in Figure 26 and Figure 27. The circuit not only allows different configurations, input range scaling, and filtering but also allows adding a dc component and using different op amps and supplies. The analog input amplifiers are set as unity-gain buffers by factory default. The amplifier positive rail is driven from 7.5 V (from U13—ADP7104). The negative amplifier rail is driven from –VS (generated by U3— ADP2301). The default configuration sets all op amps (U12 and U17) at midscale, generated from a buffered reference voltage divider (VCM). The evaluation board is configured by factory default for providing a pseudo differential analog input path to ADC1 and ADC2 (see Figure 16). For dynamic performance, an FFT test can be done by applying a very low distortion ac source. balanced with a floating ground. The J10 and J15 connectors are provided for balanced termination of a signal source. Different sources can be used; however, most are single-ended sources that use a fixed output resistance. By default, the evaluation board uses the amplifiers as unity-gain buffers. The noninverting input has a common-mode adjustment that involves a 100 kΩ shunt resistor. This resistor creates a voltage divider with the source, which must be accounted for when using the board. REFERENCE An external 5 V reference (U6—ADR435) is used to supply the ADCs directly. SERIAL INTERFACE The evaluation board uses the SPORT interface from the ADSP-BF527 DSP. Multiple AND gates (U9, U10, and U11) are used to clock and gate the SPORT transfer to the ADC device. For low frequency testing, the audio precision source can be used directly because its outputs are isolated. Set the outputs as Rev. 0 | Page 11 of 32 UG-608 EVAL-AD7902SDZ User Guide MODES OF OPERATION SDP CONTROLLED MODE STANDALONE MODE The AD7902 uses a high speed serial interface that allows sampling rates of up to 1 MSPS. For more information about the operation of the serial interface, refer to the AD7902 data sheet. The EVAL-AD7902SDZ can also be used without the EVAL-SDPCB1Z controller board. In this case, the EVAL-AD7902SDZ is connected to the serial interface using the J5 connector or the test points. For more information about the operation of the serial interface, refer to the AD7902 data sheet. The AD7902 uses the serial interface to transfer data to the EVAL-SDP-CB1Z. The EVAL-AD7902SDZ communicates with the EVAL-SDPCB1Z board using level shifters. The EVAL-SDP-CB1Z operates at a 3.3 V logic level, which allows logic voltages that exceed 3.3 V to be used without damaging the SDP interface. Rev. 0 | Page 12 of 32 EVAL-AD7902SDZ User Guide UG-608 HOW TO USE THE SOFTWARE 3. SETTING UP THE SYSTEM FOR DATA CAPTURE: BOARD OPERATION/CONNECTION SEQUENCE After finding the evaluation board, the software connects to the board and displays the dialog box shown in Figure 18. 1. 2. 3. 4. 5. Connect the SDP controller board to the evaluation board via the J5 connector (screw into place as required). The software is configured to find the evaluation board on either the J4 or J5 connector of the SDP board. Power the board with the appropriate supply, as described in the Power Supplies section. Connect the EVAL-SDP-CB1Z board to a PC using the USB cable. Start the evaluation software. Click Start > All Programs > AD7902_03_Evaluation > AD7902_03_Evaluation_ Software. Apply a signal source and capture data. STARTING THE SOFTWARE When the software starts running, it searches for hardware connected to the PC. The software automatically detects the generic attached to the PC, or you can choose to run the software in standalone mode without any hardware connected. 11798-018 With the evaluation software installed, the following board operation/connection sequence can be used: Figure 18. Software Connects to SDP Board 4. After the board is correctly detected, the main window of the software appears (see Figure 21), showing that the EVAL-AD7902SDZ board is connected. Without Hardware Connected The software can run in standalone mode when no evaluation board hardware is connected to the USB port. 1. Click Start > All Programs > AD7902_03_Evaluation > AD7902_03_Evaluation_Software. 2. The software automatically seeks to find the hardware connected; therefore, when no hardware is connected, a connectivity error is displayed (see Figure 19). If you wish to continue without hardware in standalone mode, click Cancel. With Hardware Connected To run the program with hardware connected, 1. 11798-019 2. Click Start > All Programs > AD7902_03_Evaluation > AD7902_03_Evaluation_Software. (To uninstall the program, click Start > Control Panel > Add or Remove Programs > AD7902_03_Evaluation.) If the SDP board is not connected to the USB port when the software is launched, a connectivity error displays (see Figure 17). If a connectivity error is displayed, connect the evaluation board to the USB port of the PC, wait a few seconds, click Rescan, and follow the instructions. Figure 19. No Hardware Connected Pop-Up Window Error The software alerts the user that no hardware is connected and that the software is going to continue in standalone mode. 11798-017 3. 11798-020 Figure 17. SDP Board Not Connected to the USB Port Pop-Up Window Error Figure 20. Software Indicates Operating in Standalone Mode Rev. 0 | Page 13 of 32 UG-608 You can then load example files or previously saved files and analyze data. The main window of the software appears (see Figure 21), showing the evaluation board connected as the part number from the saved data file. 5. If you decide to connect hardware at this point, you must close the software and relaunch it to allow it to search for the board again. 11798-021 4. EVAL-AD7902SDZ User Guide Figure 21. Main Window Rev. 0 | Page 14 of 32 EVAL-AD7902SDZ User Guide UG-608 OVERVIEW OF THE MAIN WINDOW The main window of the software is shown in Figure 21 and has the features described in this section. File Menu The File menu offers the choice to • • • • • Load data: load previously captured data. Save Data as .tsv: save captured data in .tsv format for future analysis. Save Picture: save the current screen capture. Print: print the main window to the default printer. Exit: close the application. sample frequency must be an integer divider of the SCLK frequency. If an unusable sample frequency is input, the software automatically adjusts the sample frequency accordingly. Units can be entered as, for example, 10k for 10,000 Hz. The software automatically adjusts the sample frequency according to the ability of the ADC connected to the board. For example, if you enter a value that is beyond the ability of the device, the software indicates this and reverts to the maximum sample frequency. Select Channels Checkboxes Select either Channel 1 or Channel 2 or both to read the data from a single ADC or both ADCs simultaneously. Tabs Area Eval Board Connected Box The Eval Board Connected box displays the evaluation board connected to the USB port—either EVAL-AD7902 or EVAL-AD7903. When an evaluation board is not connected to the USB port, the software can be operated in standalone mode for data analysis, and the part information notes the part number from the saved data file. ADC Settings Area The ADC Settings area allows changing the sampling frequency and the reference voltage value, as well as selecting Channel 1 or Channel 2. Reference Voltage (V) Box By default, the external reference voltage is 5 V (ADR435 on-board reference). The minimum/maximum voltage calculations are based on this reference voltage. If you change the reference voltage, you must change this input accordingly. Sampling Freq (Hz) Box The default sampling frequency (10000000 Hz) in the Sampling Freq (Hz) box matches the maximum sample rate of the ADC connected to the board. Although you can adjust the sampling frequency, there are limitations in terms of the sample frequencies that can be entered related to the SCLK frequency applied. The There are five tabs available in the tabs area of the main window: Configure, Waveform, Histogram, FFT, and Summary. These tabs display the data in different formats. Navigation tools are provided within each tab to allow you to control the cursor, zooming, and panning (see Figure 22) within the graphs displayed. Each tab is described in more detail in the Generating a Waveform Analysis Report; Generating a Histogram of the ADC Code Distribution; Generating a Fast Fourier Transform of AC Characteristics; and Generating a Summary of the Waveform, Histogram, and Fast Fourier Transform sections. Single Capture Button Clicking Single Capture performs a single capture from the ADC. Continuous Capture Button Clicking Continuous Capture performs a continuous capture from the ADC. Num Samples Box The Num Samples box allows you to select the number of samples to analyze. Exit Button Clicking the Exit button (in the upper right corner of the window) closes the software. Alternatively, you can select Exit from the File menu. Rev. 0 | Page 15 of 32 UG-608 EVAL-AD7902SDZ User Guide GENERATING A WAVEFORM ANALYSIS REPORT Figure 22 illustrates the Waveform tab for a 10 kHz sine wave input signal when the on-board 5 V external reference is used. The Waveform Analysis area (located toward the bottom of the window) reports the amplitudes recorded from the captured signal and the frequency of the signal tone. Select the Channel 1 tab or Channel 2 tab in the Waveform Analysis area to view the corresponding waveform. 11798-022 CONTROL CONTROL CONTROL CURSOR ZOOMING PANNING Figure 22. Waveform Tab Rev. 0 | Page 16 of 32 EVAL-AD7902SDZ User Guide UG-608 GENERATING A HISTOGRAM OF THE ADC CODE DISTRIBUTION The Histogram tab can be used to perform ac testing or, more commonly, dc testing. This tab shows the ADC code distribution of the input and computes the mean and standard deviation, which are displayed as DC Offset/Mean and Transition Noise, respectively, in the Histogram Analysis area (located toward the bottom of the window). DC Input A histogram test of dc input can be performed with or without an external source because the evaluation board has a buffered VREF/2 source at the ADC input. To perform a histogram test of dc input, 1. Figure 23 shows the histogram with ac input for a 1 kHz sine wave applied to the ADC input and the resulting calculations. 2. 3. AC Input To perform a histogram test of ac input, 1. 2. 3. Apply a sinusoidal signal with low distortion (better than 100 dB) to the evaluation board at the J6 or J14 input SMA connector pair. Click the Histogram tab from the main window. Click Single Capture or Continuous Capture. If an external source is being used, apply a sinusoidal signal with low distortion (better than 100 dB) to the evaluation board at the J6 or J14 input SMA connector pair. It may be required to filter the signal to ensure that the dc source is noise-compatible with the ADC. Click the Histogram tab from the main window. Click Single Capture or Continuous Capture. Raw data is then captured and passed to the PC for statistical computations, and various measured values are displayed in the Histogram Analysis area. 11798-023 Raw data is then captured and passed to the PC for statistical computations, and various measured values are displayed in the Histogram Analysis area. Figure 23. Histogram Tab Rev. 0 | Page 17 of 32 UG-608 EVAL-AD7902SDZ User Guide GENERATING A FAST FOURIER TRANSFORM OF AC CHARACTERISTICS Figure 24 shows the FFT tab. This feature tests the traditional ac characteristics of the converter and displays a fast Fourier transform (FFT) of the results. To perform an ac FFT test, 2. 3. Apply a sinusoidal signal with low distortion (better than 100 dB) to the evaluation board at the J6 or J14 input SMA connector pair. To attain the requisite low distortion, which is necessary to allow true evaluation of the part, one option is to a. Filter the input signal from the ac source. A band-pass filter can be used; its center frequency must match the test frequency of interest. b. If a low frequency band-pass filter is used when the fullscale input range is more than a few volts peak-to-peak, use the on-board amplifiers to amplify the signal, thus preventing the filter from distorting the input signal. Click the FFT tab from the main window. Click Sample. 1 The FFT Analysis area displays the results of the captured data. • • • 2 The area labeled 1 in Figure 24 shows the spectrum information. The area labeled 2 in Figure 24 displays the fundamental frequency and amplitude. You can also click Show Harmonic Content to view information about the second to fifth harmonics. The area labeled 3 in Figure 24 displays the performance data, including the SNR, THD, SINAD, and noise performance. 3 11798-024 1. As in the histogram test, raw data is then captured and passed to the PC, which performs the FFT and displays the resulting SNR, SINAD, THD, and SFDR. Figure 24. FFT Tab Rev. 0 | Page 18 of 32 EVAL-AD7902SDZ User Guide UG-608 GENERATING A SUMMARY OF THE WAVEFORM, HISTOGRAM, AND FAST FOURIER TRANSFORM 11798-025 Figure 25 shows the Summary tab. The Summary tab captures all the display information and provides it in one panel with a synopsis of the information, including key performance parameters, such as SNR and THD. Figure 25. Summary Tab Rev. 0 | Page 19 of 32 UG-608 EVAL-AD7902SDZ User Guide EVALUATION BOARD SCHEMATICS AND ARTWORK 11798-026 EVAL-AD7902SDZ SCHEMATICS Figure 26. Schematic, Page 1 Rev. 0 | Page 20 of 32 UG-608 11798-027 EVAL-AD7902SDZ User Guide Figure 27. Schematic, Page 2 Rev. 0 | Page 21 of 32 UG-608 EVAL-AD7902SDZ User Guide 11798-028 Figure 28. Schematic, Page 3 Rev. 0 | Page 22 of 32 EVAL-AD7902SDZ User Guide UG-608 11798-029 Figure 29. Schematic, Page 4 Rev. 0 | Page 23 of 32 UG-608 EVAL-AD7902SDZ User Guide 11798-030 Figure 30. Schematic, Page 5 Rev. 0 | Page 24 of 32 EVAL-AD7902SDZ User Guide UG-608 11798-031 Figure 31. Schematic, Page 6 Rev. 0 | Page 25 of 32 UG-608 EVAL-AD7902SDZ User Guide EVAL-AD7902SDZ LAYOUT Layout Considerations When laying out the printed circuit board (PCB) for the AD7902, follow the recommended guidelines described in this section to obtain the maximum performance from the converter. Figure 33 through Figure 36 show the recommended layout for the AD7902 evaluation board. Decouple all the power supply pins (VDD1, VDD2, and VIO) and the REF pin with low ESR and low ESL ceramic • 11798-032 • • capacitors, typically 10 µF and 100 nF, placed close to the DUT (U1) and connected using short, wide traces to provide low impedance paths and to reduce the effect of glitches on the power supply lines. Separate analog and digital sections and keep power supply circuitry away from the AD7902. Avoid running digital lines under the device and crossover of digital and analog signals because these couple noise into the AD7902. Figure 32. EVAL-AD7902SDZ Evaluation Board Silkscreen—Top Assembly Rev. 0 | Page 26 of 32 UG-608 11798-033 EVAL-AD7902SDZ User Guide 11798-034 Figure 33. EVAL-AD7902SDZ Evaluation Board—Top Layer Figure 34. EVAL-AD7902SDZ Evaluation Board Layer 2—Ground Rev. 0 | Page 27 of 32 EVAL-AD7902SDZ User Guide 11798-035 UG-608 11798-036 Figure 35. EVAL-AD7902SDZ Evaluation Board Layer 3—Power Figure 36. EVAL-AD7902SDZ Evaluation Board Bottom Layer Rev. 0 | Page 28 of 32 EVAL-AD7902SDZ User Guide UG-608 BILL OF MATERIALS Table 4. EVAL-AD7902SDZ Bill of Materials Reference Designator U1 U2 U3 U4 U5 U6 U7 Part Description Dual pseudo differential 16-bit, 1 MSPS PulSAR ADC 1.2 A, 20 V, 1.4 MHz nonsynchronous stepdown switching regulator 1.2 A, 20 V, 1.4 MHz nonsynchronous stepdown switching regulator Linear regulator, 3.3 V, 20 V, 500 mA, ultralow noise, CMOS 2.7 V, 800 µA, 80 MHz rail-to-rail I/O single amplifier SOT23-5 Ultralow noise XFET voltage references Manufacturer Analog Devices Part Number AD7902 Stock Code AD7902 Analog Devices ADP2301AUJZ ADP2301AUJZ-R7 Analog Devices ADP2301AUJZ ADP2301AUJZ-R7 Analog Devices ADP7104ARDZ-3.3 ADP7104ARDZ-3.3-R7 Analog Devices AD8031ARTZ AD8031ARTZ-R2 Analog Devices ADR435BRZ ADR435BRZ Analog Devices ADP7104ARDZ-2.5 ADP7104ARDZ-2.5-R7 U8 Linear regulator, 2.5 V, 20 V, 500 mA, ultralow noise, CMOS Single INV Fairchild NC7SZ04M5 Farnell 1013809 U9 Single AND gate Fairchild NC7SZ085M5 Farnell 1013807 U10 Single AND gate Fairchild NC7SZ085M5 Farnell 1013807 U11 Single AND gate Fairchild NC7SZ085M5 Farnell 1013807 U12 Analog Devices ADA4841-1YRZ ADA4841-1YRZ-R7 U13 Low noise, high speed amplifier for 16-bit systems 20 V, 500 mA, low noise, CMOS adjustable LDO Analog Devices ADP7104ARDZ ADP7104ARDZ-R7 U14 Not applicable Not applicable Not applicable Do not place U15 32k I2C serial EEPROM, 8-lead MSOP Microchip 24LC32A-I/MS Farnell 1331330 U16 Not applicable Not applicable Not applicable Do not place U17 Low noise, high speed amplifier for 16-bit systems Capacitor tantalum, 20 V Analog Devices ADA4841-1YRZ ADA4841-1YRZ-R7 AVX TAJB106K020RNJ Farnell 197427 Capacitor ceramic, 4.7 µF, 16 V, X7R, 0805 Taiyo Yuden EMK212B7475KG-T Farnell 1853520 C8, C20, C23, C25, C27, C28, C30, C31, C34, C37, C41, C42, C44, C53, C54, C56, C57, C59, C77, C78 C9 Capacitor ceramic, 50 V, X7R Murata GRM188R71H104KA93D Farnell 8820023 Capacitor ceramic, 50 V, X7R, 0805 Murata C0805C104K5RACTU Farnell 1414664 C12, C40, C79 Capacitor ceramic, 22 µF, 10 V, X7R, 1206 AVX LMK316AB7226ML-TR Farnell 1894515 C14 Capacitor ceramic, 4.7 µF, 16 V, X5R, 1206 Taiyo Yuden EMK316BJ475KL-T Farnell 6578937 C15, C16, C17, C21, C22, C26 C18 Capacitor, 0805, 1 µF, 50 V, X7R Murata GRM21BR71H105KA12L Farnell 1735541 Capacitor ceramic, 50 V, X7R Murata GRM188R71H103KA01D Farnell 1118178 C33, C58 Capacitor ceramic ,10 pF, 100 V, C0G, 0603 AVX 06031A100JAT2A Farnell 1273324 C35, C74 Capacitor ceramic, 2700 pF, 50 V, C0G/NP0, 0603 TDK C1608C0G1H272J Farnell 1844178 C1, C2, C5, C9, C11, C13, C19 C3, C4, C6, C7 Rev. 0 | Page 29 of 32 UG-608 EVAL-AD7902SDZ User Guide Reference Designator C24, C29, C32, C36, C38, C39, C43, C45, C46, C47, C48, C49, C50, C51, C52, C55, C60, C61, C62, C63, C65, C66, C67, C68, C69, C70, C71, C72, C73, C75, C76, C80, C81 R1 Part Description Not applicable Manufacturer Not applicable Part Number Not applicable Stock Code Do not place Resistor, thick film, 2.4 kΩ, 0603, 100 mW, 1% Yageo RC0603FR-072K4L Farnell 1799329 R2 SMD resistor Multicomp MC 0.1W 0805 1% 62K Farnell 9333436 R3 Resistor, 0603, 35.7 kΩ Multicomp Farnell 1170942 R4 SMD resistor Multicomp R5 SMD resistor Multicomp R6 Resistor, 0603, 16.9 kΩ Multicomp R7 Resistor, 0805, 12.1 kΩ, 1% Vishay Draloric MC 0.063W 0603 1% 35K7 MC 0.0625W 0402 1% 53K6 MC 0.0625W 0402 1% 10K2 MC 0.063W 0603 1% 16K9 CRCW080512K1FKEA R10 Resistor, 0603, 82 kΩ, 0.063 W, 1% Multicomp R11, R13, R42, R44 SMD resistor Multicomp R12, R15 Resistor, 20 kΩ, 0.063 W, 1%, 0603 R14, R20, R21, R23, R25, R26, R36, R45, R48, R53, R63, R69, R70, R71, R72 R17, R22, R46, R47 Farnell 1803723 Farnell 1803137 Farnell 1170908 Farnell 1469866 Multicomp MC 0.063W 0603 1% 82K MC 0.063W 0603 1% 100K MC 0063W 0603 1 20K Farnell 9330771 SMD resistor Multicomp MC 0.063W 0603 0R Farnell 9331662 Resistor, 0805, 49.9 Ω, 0.1%, 0.125 W Panasonic ERA6AEB49R9V Farnell 1810805 R28, R35, R50, R74 Resistor, 2 kΩ, 0.1 W, 1%, 0805 Multicomp MC 01W 0805 1 2K Farnell 9332766 R27, R34, R49, R73 Resistor, 100 kΩ, 0.1 W, 1%, 0805 Multicomp MC 01W 0805 1 100K Farnell 9332405 R24, R67 Resistor, 22 Ω, 1% 0805 Vishay Draloric CRCW080522ROFKEAHP Farnell 1738936 R8, R9, R16, R18, R19, R29, R30, R31, R32, R33, R37, R38, R39, R40, R41, R44, R54, R55, R56, R59, R60, R61, R62, R64, R65, R66, R68 Not applicable Not applicable Not applicable Do not place Rev. 0 | Page 30 of 32 Farnell 9331573 Farnell 9330402 EVAL-AD7902SDZ User Guide UG-608 RELATED LINKS Resource AD7902 ADA4841-1 AD8031 ADP7104 ADP2301 ADR435 Description Product Page: Dual Pseudo Differential 16-Bit, 1 MSPS PulSAR ADC Product Page: Unity Gain Stable, Low Noise and Distortion, Rail-to-Rail Output Amplifier Product Page: 2.7 V, 800 μA, 80 MHz Rail-to-Rail I/O Amplifiers Product Page : 20 V, 300 mA/500 mA, Low Noise, CMOS LDO Product Page: 1.2 A, 20 V, 1.4 MHz, Nonsynchronous Step-Down Regulator Product Page: Ultralow Noise, High Accuracy Voltage References Rev. 0 | Page 31 of 32 UG-608 EVAL-AD7902SDZ User Guide NOTES ESD Caution ESD (electrostatic discharge) sensitive device. Charged devices and circuit boards can discharge without detection. Although this product features patented or proprietary protection circuitry, damage may occur on devices subjected to high energy ESD. Therefore, proper ESD precautions should be taken to avoid performance degradation or loss of functionality. Legal Terms and Conditions By using the evaluation board discussed herein (together with any tools, components documentation or support materials, the “Evaluation Board”), you are agreeing to be bound by the terms and conditions set forth below (“Agreement”) unless you have purchased the Evaluation Board, in which case the Analog Devices Standard Terms and Conditions of Sale shall govern. Do not use the Evaluation Board until you have read and agreed to the Agreement. Your use of the Evaluation Board shall signify your acceptance of the Agreement. This Agreement is made by and between you (“Customer”) and Analog Devices, Inc. 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