® DEM-ADS1250 EVALUATION FIXTURE FEATURES DESCRIPTION ● ● ● ● The ADS1250U evaluation fixture provides an easy and efficient method of evaluating the ADS1250U. The evaluation fixture and PC software function as a complete data acquisition system using a standard parallel port. Data can be collected, analyzed, and stored in either the time domain or frequency domain. ● ● ● ● EASY TO USE GRAPHICAL INTERFACE Windows® 95 COMPATIBLE SOFTWARE COLLECTS UP TO 32,768 CONVERSIONS RETRIEVED DATA CAN BE VIEWED IN TIME DOMAIN, FFT, OR AS INDIVIDUAL SAMPLES HISTOGRAM FUNCTION DISPLAYS NOISE DISTRIBUTION AUTOMATICALLY CALCULATES STANDARD DEVIATION, MEAN, SNR, SINAD, THD, AND SFDR DATA CAN BE SAVED IN ASCII FORMAT (EASILY IMPORTED INTO MICROSOFT® EXCEL) GRAPHS MAY BE PRINTED OR EMBEDDED INTO OTHER WINDOWS APPLICATIONS The time domain analysis includes a histogram feature which allows for verification of low noise and no missing code performance. The frequency domain analysis uses conventional FFT plots. The FFT analysis can also be modified with a user-selectable FFT window. The time domain or frequency domain data can be collected and displayed in either an on-demand or periodic basis. The design of the evaluation fixture’s hardware allows the user to choose between several configurations, including single-ended or differential mode input signals. An offboard reference voltage may also be applied to the device. Test points are included for all digital signaling. In addition, a small prototyping area is available on the analog board. International Airport Industrial Park • Mailing Address: PO Box 11400, Tucson, AZ 85734 • Street Address: 6730 S. Tucson Blvd., Tucson, AZ 85706 • Tel: (520) 746-1111 Twx: 910-952-1111 • Internet: http://www.burr-brown.com/ • Cable: BBRCORP • Telex: 066-6491 • FAX: (520) 889-1510 • Immediate Product Info: (800) 548-6132 © 1999 Burr-Brown Corporation LI-544 Printed in U.S.A. November, 1999 SYSTEM REQUIREMENTS SETTING BOARD JUMPERS Windows® 95 Standard Parallel Port +5V DC Power Supply ±15V DC Power Supply (for single-ended to differential signal converter) • 6.2Mb free space on hard drive (maximum required) • ADS1250 Demo Hardware The analog board has several configuration jumpers. The most important of these jumpers are the analog input selection jumpers (JMP1, JMP15, and JMP21-24). Direct connection allows both the positive and negative input of the part to be provided by external sources (see Figure 1). To connect directly to the inputs (J3 and J4), set the jumpers as shown in Table I. • • • • CONNECTING THE HARDWARE The ADS1250 demonstration system contains two printed circuit boards. The first board is the computer interface board (A2702), which handles data buffering and parallel port communication. The second is the analog board (PR277) which contains the ADS1250 and all the support circuitry. The computer interface board buffers the data from the ADS1250 chip so that the data can be transferred to the computer for analysis. The data link between the interface board and the computer is comparatively slow, so the data is first stored in buffer memory on the interface board and then transferred to the computer. The Intel-compatible computer connects to the interface board via the 25-pin cable. The female end of the cable connects to J1 on the interface board. The male end of the cable connects to the female parallel port connector on the back of the computer. The analog board connects to the interface board via a 36conductor ribbon cable. The cable is designed to lay flat in between the boards. Do not twist the ribbon cable when connecting the two boards (the connectors are not polarized). It does not matter which direction the ribbon cable exits the connector. Both boards must now be connected to a +5V DC supply (the same unit can supply both boards). Connector P3 on the interface board is the DC power input. Connector J1 on the analog board is the other DC power input. Connector J5 on the analog board is the DC power for the ±15V supply. NOTE: Parallel ports are female 25-pin connectors, serial ports are male 25-pin connectors. Do not connect to a serial port. Do not “daisy-chain” the interface board with any other device. The demonstration board was designed to work on a dedicated parallel port. JUMPER POSITION JMP1 N/A JMP15 2-3 JMP21 2-3 JMP22 2-3 JMP23 2-3 JMP24 2-3 TABLE I. Direct Differential Connection. JMP1 1 ADS1250 JMP23 1 JMP21 1 JMP24 JMP15 1 J3 Negative 1 JMP22 J4 Positive 1 FIGURE 1. Jumper Settings for Direct Connection to Analog Inputs. If the application requires a fixed common-mode voltage, the board can be set to provide 2.5V DC common mode (see Figure 2). The conversion circuitry is connected by the jumper settings in Table II. JUMPER POSITION JMP1 1-2 JMP15 1-2 JMP21 N/A JMP22 1-2 JMP23 1-2 JMP24 1-2 TABLE II. Single-Ended Connection with 2.5V Common Mode. ® DEM-ADS1250 2 +5VDC JMP1 1 1kΩ 5kΩ 5kΩ 1kΩ JMP23 1 ADS1250 JMP21 1 JMP24 JMP15 1 1 JMP22 J4 Positive 1 NOTE: The supply connected to J4 (Positive Channel) must be floating (i.e., it must not share a ground connection with the power supply). There is a gain of 2 associated with J4 (Positive Channel). FIGURE 2. Jumper Settings for a Fixed Common-Mode Voltage to Analog Inputs. The analog input can also be shorted directly to demonstrate rms noise. To short the analog input, set the jumpers for direct connection. Disconnect any sources at J3 and J4, and connect jumper JMP17. If the user wants to provide an arbitrary common-mode signal, single-ended connection allows the input to be converted from two single-ended sources to a differential input for the chip. J4 is the input for the signal, and J3 is the input for the common-mode voltage (see Figure 3). The conversion circuitry is connected by the jumper settings in Table III. JUMPER NOTE: Remember to remove the shorting jumper after the test. If an external reference is to be used, connect the reference voltage to J2. To select the external reference voltage, set JMP11 to position 2-3. To return to the internal voltage, set JMP11 to position 1-2. POSITION JMP1 2-3 JMP15 1-2 JMP21 1-2 JMP22 1-2 JMP23 1-2 JMP24 1-2 There are several jumper locations on the board that do not have header pins installed. These jumpers were included in case the user wished to directly connect a logic analyzer or apply external digital signals. For logic analyzers, a wire may be soldered into one of the open pin holes. For external digital signals, cut the copper trace on the board in between the jumpers. Refer to Figure 15 for connections of the jumpers. TABLE III. Single-Ended Connection. JMP1 1 1kΩ JMP23 1 ADS1250 1kΩ JMP21 1 JMP24 J3 Negative JMP15 1 1 JMP22 1 J4 Positive NOTE: The supply connected to J4 (Positive Channel) must be floating (i.e., it must not share a ground connection with the supply on J3). There is a gain of 2 associated with J4 (Positive Channel). FIGURE 3. Jumper Settings for a Single-Ended-to-Differential Voltage to Analog Inputs. ® 3 DEM-ADS1250 INSTALLING A PART IN THE SOCKET INSTALLING THE SOFTWARE The Robinson Nugent low profile socket on the analog board has an ADS1250 installed as part of the kit. If the user wants to change the part, use caution to properly orient the part in the socket. To install the software, first close all applications running on the computer. If you do not close all applications, the install may fail because a Windows system file could be in use. Insert Disk 1 into the floppy disk drive. Click on the Start button. Select RUN... and type A:setup in the dialog box (assuming that A: is the drive that the disk is in). The setup installation program will prompt for the installation directory (the default is recommended). The installation program will prompt when the other disks in the set are needed. The latching cover can be removed by using a small screwdriver or pair of tweezers to dislodge the mounting clips at either end of the lead cover (remember to turn the power off before attempting). The new part is placed with pin 1 (nearest the small dimple in the package) oriented to the label “PIN 1” on the silkscreen (see Figure 4). There should be no space between the part and pin 1 in the socket. The setup program installs or updates all the necessary Windows system DLLs and OCX controls. The actual program files are stored in C:\program files\demo1250. Setup will also create an icon in the Start menu for the Demo1250 program. If it is necessary to remove the Demo1250 software, open the control panel and click on Add/Remove Programs. The Demo1250 software will be listed as an option for uninstall. COLLECTING DATA FOR THE FIRST TIME Socket Base Lead Cover Start the software by selecting the Demo1250 icon from the Start menu (Start/Programs/Demo1250). The program will display an empty graph when it starts, as shown in Figure 5. Correct Orientation FIGURE 4. Device Orientation in Socket. TROUBLESHOOTING • If the red LED on the analog board is not lit, then +5V is not being applied to the board. • If either of the green LEDs on the interface board is not lit, the Xilinx chips are not loaded properly. This may occur if power is not applied or the socketed chips (U1, U2, U5 and U6) are not making a good connection. • The Xilinx chips will fail to load (no green LEDs) if the rise time of the +5V DC power supply is less than 25ms. • There should not be a twist in the cable between the PC interface board and the analog board. • The cable for the parallel port does not require any type of adapter to connect to the PC. The connector on the PC will be a 25-pin female connector. FIGURE 5. ADS1250 Demonstration Software Screen. • If the supply wires are accidentally connected backwards, correct the problem and then wait approximately 20 seconds before applying power. The supply lines have resettable fuses which must cool down before they will reset. The next step is to set the program for the correct parallel port. Click on the menu titled “Settings” and an options dialog box will appear. Click on the tab labeled “Computer”. Press the button labeled “Run Autodetect” and the program will display the parallel ports detected on the computer. ® DEM-ADS1250 4 Set the combo box for the port address of the parallel port the interface board is connected to. Click on “OK” (see Figure 6). SETTING HARDWARE OPTIONS FOR THE ADS1250 FIGURE 6. Parallel-Port Detection Screen. FIGURE 8. Hardware Configuration Screen. The option dialog will disappear and the empty graph will display again. To retrieve data from the board, click on the menu icon that looks like a camera (or press CTRL-D). If everything is working correctly, the status bar at the bottom of the window will count up and a time domain graph of the collected data will appear on the screen, as shown in Figure 7. The “Hardware” tab of the options dialog box will allow changes to the following parameters: Clicking on the menu option “Settings” will open up the options dialog box shown in Figure 8. Gain Range: Click on the radio button for the gain setting that is to be used. Output Format: This option controls the display of the data on the time domain graph. Unchanged integer is the data directly from the chip. Full-Scale Normalized to 1 adjusts the data so that full-scale range is ±1 (the data from the chip is scaled). Voltage adjusts the data so that the display is in volts (assuming a 4.1V reference). Chip Select: By default, chip select is only active when communication with the chip occurs. Setting this option forces chip select to be active all the time. Serial Clock: It is only necessary to pulse the data clock when data is being shifted out of the chip. Setting this option forces the data clock to be on all the time. Serial Synchronization: Communication with the chip is normally synchronized to the rising edge of the main clock. Setting this option forces the data to synchronize with the falling edge of the clock. Read-Back Delay: This option adds a delay time between chip select asserted low and serial clock pulses. The number displayed represents the number of clock cycles. FIGURE 7. Data Retrieval Screen. Serial Frequency: This option reduces the clock frequency of the serial clock. The default clock frequency is fs/2, where fs is the main clock frequency. To adjust the number of samples retrieved from the board, move the slider at the bottom of the window or insert the desired number into the numerical display. For detailed software instructions, read the section titled “Exploring Retrieved Data.” Oscillator Frequency: This adjusts software delays and the FFT plot, if the user replaces the oscillator on the interface board with another frequency. The oscillator frequency is not changed by this option; it is simply used to display information in the proper format. If the graph did not display or if a flat line is displayed, recheck all the cable connections for data and power to the two demo boards. ® 5 DEM-ADS1250 EXPLORING RETRIEVED DATA In order to activate any of the changes, the button “OK” or “Apply” must be pressed after the changes are made. If the button “Cancel” is pressed or the window is closed, no changes will be made. Retrieving Data There are two methods for data retrieval: single capture and continuous read. For single capture, press the toolbar button that looks like a camera, or type CTRL-D. This will trigger a single read cycle. NOTE: The ADS1250 does not support “Chip select always low” and “Serial clock always on” at the same time. Continuous read mode will trigger a new read cycle 0.5 seconds after the previous cycle is done. To activate continuous read, press the toolbar button that looks like a stopwatch, or type CRTL-R. To deactivate continuous read, simply repeat the command. SETTING FFT OPTIONS FOR THE ADS1250 Clicking on the menu option “Settings” and selecting the “FFT” tab will open up the options dialog box shown in Figure 9. At the bottom of the main window is a scroll bar and text box. This is the control for the number of samples collected. Slide the bar or input a new number in the box to change the number of samples. The maximum number of samples that can be collected is 32,768. Viewing Data Data can be viewed on screen four different ways: as a time domain plot, a Fast Fourier Transform, a hexadecimal table, or as a histogram. To select the different views, choose from among the four buttons on the toolbar or select from the View menu. FIGURE 10. Toolbar. FIGURE 9. FFT Configuration Screen. Graph Options The “FFT” tab of the options dialog box will allow changes to the following parameters: All the selections for changing the display of the graphs are accessed by right-clicking on the graph itself. This will display a small pop-up list of options as shown in Figure 11. FFT Window: This group of radio buttons allows selection of different windows for the FFT data. For evaluations of a low noise part like the ADS1250, sophisticated windows like Continuous 5th Derivative and Blackman-Harris are recommended. Calculations: The calculations for the SNR, THD, SFDR, and SINAD are based on the number of FFT bins shown. If a different resolution is required, the number of bins used can be changed here. Display: For further insight into the FFT calculations, the checkboxes in this section will display markers on the FFT plot which define the bin boundaries used. In order to activate any of the changes, the button “OK” or “Apply” must be pressed after the changes are made. If the button “Cancel” is pressed or the window is closed, no changes will be made. FIGURE 11. Graphic Options Pull-Down Menu. ® DEM-ADS1250 6 Viewing Style selects color or black and white display. Font Size changes the size of the titles and labels on the graph. Numeric Precision changes the number of significant digits after the decimal point. Plotting Method allows the selection of different plot types (e.g., line, bar, point, etc.). Data Shadows displays a dark background behind the data in some plotting methods. Grid Lines controls the display of the X and Y axis grid lines. Grid In Front is used to force the display of the grid. Include Data Labels will display the X and Y coordinates of every point on the graph. Mark Data Points will place a marker at each data point for easy viewing. The export dialog allows the user to choose between a Windows MetaFile (for embedding into another application), a bitmap (a exact replica of what is displayed on the screen), and text. The user can also export to the clipboard, a file, or the printer. Saving Data Aside from exporting data from the graphs, it is possible to save the collected data directly to a text file. Choosing Save from the File menu will save data to a comma-delimited text file that is compatible with Microsoft Excel (.csv). The data which is saved depends on the active plot. If the time domain plot is visible, the time domain points will be saved to the disk. If the FFT plot is visible, then the individual points of the FFT will be saved. The time domain data is saved in a single column as shown in Figure 13. The FFT data is also saved in a single column as shown in Figure 14. To have the graph fill the entire screen, select the Maximize option. This option is useful as a print preview of the graph. To add annotation to the graph, such as custom titles, select the Customization Dialog option. This will open a dialog screen which will allow edits of titles and labels. Zooming To zoom in on any section of the time domain graph, simply left-click and drag over the area of interest. A shaded box will appear when dragging over the area. To undo the zoom, right-click to display the pop-up menu and choose the option for Undo Zoom. The FFT graph will only zoom on the X axis. Printing Printing may be started by pressing the printer icon, or by selecting Print from the File menu. A small dialog box will appear and allow printer selection and setup. Page setup may also be accessed through the File menu. The print function only prints the current graph. The hexadecimal table will not print. Exporting Data To export data to other applications, right-click on the current graph and choose the option for export dialog shown in Figure 12. FIGURE 13. ADS1250 Data File Time Domain Samples. FIGURE 12. Export Dialog Screen. FIGURE 14. ADS1250 Data File FFT Samples. ® 7 DEM-ADS1250 PARTS LIST PC INTERFACE BOARD (A2702) PART LOCATION # PER KIT PART NUMBER VENDOR U1, U2 2 XC3142A-3PC84C Xilinx Programmable Gate Array U1, U2 (sockets) 2 PCS-084A-1 Augat 84-Pin PLCC Socket C8, C10 2 503AHL Rogers U5, U6 2 AT17C65 Xilinx Gate Array Control Prom U5, U6 (sockets) 2 508-AG11D-E-S Augat 8-Pin Single Wide DIP Socket U8, U9, U10 3 IDT71256SA15TP IDT U12 1 74HCT244N TI U3, U4, U11 3 74HCT541N TI J1 1 747842-6 AMP J2 1 3431-1202 3M LED1, LED2 2 CMD5453 Chicago Miniature U7 1 US-685-96 US Crystal RN1, RN2 2 CSC10A-01-103F Dale 10-Pin SIP Resistor Network (10kΩ, 9R, 1C) R1-R4, R6-R14, R16 14 RN55C4751F Dale 4.7kΩ Resistor, 1% R5, R15 2 RN55C1001F Dale 1kΩ Resistor, 1% R22-R25 4 RN55C1002F Dale 10kΩ Resistor, 1% D1 1 1N5820 Motorola C2-C7, C9, C11, C13, C14 10 C320C104K1R5CA Kemet C1 1 T110B106K020AS Kemet P3 1 2SV-02 Augat/RDI Stand-Offs 8 313-6487-016 E.F. Johnson Screws 8 F1 1 Decoupling Capacitors for Xilinx 8x32K Static RAM Digital Buffers Digital Buffers 25-Pin Male Right-Angle D Connector 34-Pin Male Ribbon Connector LED (2V, 20mA) 9.6MHz Clock Oscillator 1W Diode 0.1µF Capacitors 10µF Tantalum Capacitor, 20V, 10% Terminal Block 1/2" Hex Spacer, 6-32 1/4" Round Head Screw, 6-32 RUE090 Raychem ® DEM-ADS1250 DESCRIPTION 8 PolySwitch Resettable Fuse PARTS LIST (Cont.) DUT BOARD (PR277) PART LOCATION # PER KIT PART NUMBER VENDOR 13 T491C106K020AS Kemet 10µF, 20V Tantalum Capacitor 13 C1206C104K5RAC Kemet 0.1µF, 50V Ceramic Capacitor Kemet 0.1µF, 100V Ceramic Capacitor 0.01µF, 50V Ceramic Capacitor C1, C4, C9, C11, C13, C18, C20, DESCRIPTION C22, C23, C25, C27, C28, C29 C2, C5, C10, C12, C14, C17, C19, C21, C24, C26, C30, C31, C32 C3, C7 0 C6 1 C322C104K1R5CA Not Installed C8 1 C1206C103K5RAC Kemet D1 1 LM4040AIZ-4.1 National D2, D4, D5 1 1N5821 Motorola D3 1 HLMP-3201 HP DUT1 1 SOP-20B-SMT-TT Robinson Nugent F1-F3 3 RUE090 Raychem J1 1 ED1930 On-Shore Tech J2-J4 3 227161-2 AMP J5 1 ED1931 On-Shore Tech JMP1, JMP11, JMP15, 7 TSW-103-07-T-S Samtec 3-Pin Header, 100mil JMP17 1 TSW-102-07-T-S Samtec 2-Pin Header, 100mil P1 1 3431-1202 3M R1-R2 2 CRCW12061001F Dale 1kΩ Resistor, 0.1% R15 1 RN55C4991B Dale 4.99kΩ Resistor, 0.1% R16 1 RN55C1002F Dale 10kΩ Resistor, 1% R18 1 CRCW12065620F Dale 562Ω Resistor, 1% R19-R27 9 CRCW12061000F Dale 100Ω Resistor, 1% R28 1 CRCW120610R0F Dale 10Ω Resistor, 1% Dale 10Ω Resistor, 1% 4.99kΩ Resistor, 1% Voltage Reference, 4.1V 1W Diode LED (2V, 20mA) 20-Pin SOIC socket PolySwitch Resettable Fuse Terminal Block, 2 Position Right-Angle BNC Connector Terminal Block, 3 Position JMP21-JMP24 R29 1 RN55C10R0B R3-R4 2 FRJ-55 R9, R12 2 CRCW12064991F Dale 34-Pin Male Ribbon Connector 0Ω Resistor Screws 4 Stand-offs 4 313-6487-016 E.F. Johnson 1/4" Round Head Screw, 6-32 1/2" Hex Spacer, 6-32 U1, U4 2 OPA350U Burr-Brown Single-Supply Op Amp U2 1 74HCT244N TI U3 1 74HCT541N TI U5, U6 2 OPA627BP Burr-Brown 10 50863-5 AMP 8 SNT-100-BK-T Samtec Jumper Block PART NUMBER VENDOR DESCRIPTION Digital Buffers Digital Buffers Bipolar Op Amp Pin Sockets CABLES PART LOCATION # PER KIT Parallel Port 6 Feet AC25G AMP Parallel Port 1 CMM25G CW Industries 25-Pin D-Sub Male Connector 25-Conductor Ribbon Cable Parallel Port 1 CFM25G CW Industries 25-Pin D-Sub Female Connector PC Interface to DUT Board 2 3414-6034 3M PC Interface to DUT Board 6 Inches AC34G AMP 34-Pin Wiremount Socket 34-Conductor Ribbon Cable ® 9 DEM-ADS1250 FIGURE 15a. Schematic for Device Board (PR277). ® DEM-ADS1250 10 FIGURE 15b. Schematic for Device Board (PR277). ® 11 DEM-ADS1250 FIGURE 16a. Schematic for PC Interface Board (A2702). ® DEM-ADS1250 12 FIGURE 16b. Schematic for PC Interface Board (A2702). ® 13 DEM-ADS1250 ® DEM-ADS1250 14 FIGURE 17. Layout of Device Board, Top Side (PR277). 15 DEM-ADS1250 ® FIGURE 18. Layout of Device Board, Bottom Side (PR277). ® DEM-ADS1250 16 FIGURE 19. Layout of PC Interface Board, Top Side (A2702). 17 DEM-ADS1250 ® FIGURE 20. Layout of PC Interface Board, Bottom Side (A2702).