The AD9578 evaluation board is a compact, easy-to-use platform for evaluating all features of the AD9578. The AD9578 is a programmable synthesizer intended for jitter attenuation and asynchronous clocking applications in high performance telecommunications, networking, data storage, serializer/deserializer (SERDES) and physical layer (PHY) applications. The evaluation board consists of one prepopulated 49.152MHz crystal and optional single ended SMA inputs to drive the XO2 and XO4 pins. Each output is accessed through edge launch ac-coupled SMA connectors. The on board power supply allows users to simply operate the AD9578 with 2.5V or 3.3V voltages by altering a few jumper settings. Use this user guide in conjunction with the AD9578 data sheet and the evaluation software available at en/design-center/evaluation-hardware-and-software/evaluation-boards-kits/EVAL-AD9578.html#eb-overview.
The following instructions are for setting up the physical connections to the AD9578/PCBZ evaluation board.
The AD9578/PCBZ is setup by default to power the AD9578 and remaining circuitry with 3.3V using the provided 6V wall power supply. The evaluation board can be configured to operate at 2.5V when using the 6V wall supply by removing jumpers P507 and P509. Make sure the jumper P508 is between pins 1 and 2.
An external power source may be connected to both the AD9578 and digital circuitry by using header P506. The AD9578 and digital circuitry must operate at the same voltage level for proper functionality. To connect an external supply:
The following instructions assume the evaluation board is set up with the default power configuration as described in the Power Connections section.
Refer to the Evaluation Board Software section for details on running the AD9578 evaluation board software.
The AD9578 evaluation board comes prepopulated with a 49.152MHz crystal (Y101) across the XO1 and XO2 pins. Crystal Y102 connects to the XO3 and XO4 pins and is not prepopulated. Any crystal between 22MHz and 54MHz in a 3.2mm x 2.5mm package is suitable but care must be taken to select the proper load capacitance to ensure oscillation.
The REFOUT output (J217 and J218) can be configured to be a copy of either XO input or a divided version of the applied REFCLK input (includes divide by 1). The frequency source of OUT1 and OUT2 is PLL1 and the source of OUT3 and OUT4 is PLL2. The logic level of each output is selectable between CMOS, HCSL, LVDS and LVPECL. All outputs are terminated as 3.3V LVPECL by default and ac coupled to their respective SMA connectors. Using any logic type other than LVPECL will require modifications to the terminations. Refer to the AD9578 datasheet for the recommended termination for each logic type.
The AD9574/PCBZ default configuration allows a PC running the AD9578 evaluation software to read and write the various registers of the AD9578 via a USB connection. The user may interface with the SPI bus from an external SPI controller by removing jumpers P107-P110 and driving the appropriate signals to the SDO, SCK, CSB, and SDI nodes at the pin 2 of the P107-P110. As GND, use TP102 point.
Use the following instructions to set up the AD9578 evaluation board software.
Connect the evaluation board to the PC until the software installation is complete.
Power up and connect the evaluation board to the PC. See the Evaluation Board Hardware section for details on the various connectors on the evaluation board. At start up, the AD9578 evaluation software checks to see if an evaluation board is connected. If no board is connected, the message in Figure 2 will appear.
Clicking OK allows the software to be used without a connected evaluation board. This mode is convenient for creating register setup files when an evaluation board is not present. If an evaluation board is present and the error message appears, check power and USB connections and re start the program. If the evaluation board is connected before starting the program, the standard GUI appears as shown in Figure 6. It is possible to connect the evaluation board after the software is started by selecting File/Select Hardware after the board has been powered and USB cable connected. When a board is properly connected, Read All Successful will appear in the Comments box.
The AD9578 software allows the user to save a setup file containing all of the current register settings generated by the software, which can be later read, and re used.
To create a setup file:
To load a setup file:
Once the evaluation software is loaded and the evaluation board is connected, use the following steps to lock both PLLs on the AD9578. These steps use the on board 49.152MHz crystal as a reference for both PLL1 and PLL2 and the default power configuration using the provided 6V wall supply as described in the Evaluation Board Hardware section. The quick start guide covers only simple PLL operation. See the AD9578 datasheet and Evaluation Software Components section for a detailed explanation of the various AD9578 features. The following case is an example of the AD9578 using the values in Table 1.
Table 1. Quick Start Summary
|Input Frequency||49.152MHz across XO1 and XO2|
|PLL1 Reference Selection||Crystal 1|
|PLL2 Reference Selection||Crystal 1|
|OUT1 Frequency and Logic Type||125MHz LVPECL|
|OUT2 Frequency and Logic Type||156.25MHz LVPECL|
|OUT3 Frequency and Logic Type||Disabled|
|OUT4 Frequency and Logic Type||155.52MHz LVPECL|
|REFOUT Frequency and Logic Type||Disabled|
Upon startup, many controls in the AD9578 main window are inactive and grayed out. To manipulate all controls within the main window check the Advanced box in the lower right corner of the main window.
Checking the Advanced box expands the main window to include a full register map and many other features, which are explained in the following sections of the user guide.
Certain combinations of values can cause the AD9578 operating parameters to exceed the valid ranges specified in the datasheet. In these cases, the invalid entry will be highlighted in yellow and a message will appear in the Comments box explaining why the entry is invalid.
The following conditions are checked within the software:
The Autocalculate button takes the user defined reference input and output frequency parameters and automatically configures the proper PLL settings using the Frequency Wizard. Autocalculate is disabled in Advanced Controls mode. For more information on the Frequency Wizard and Advanced Controls, refer to the respective sections in this document.
The Configure button loads all of the parameters from the GUI into the AD9578 on the evaluation board. “Write All Successful” will appear in the comments box upon the completion of a successful write operation.
The Read button reads the current register values from inside the AD9578 and loads them into the Main Window. “Read All Successful” will appear in the comments box upon the completion of a successful read operation.
The input frequency section of the Main Window is used to identify the reference input frequency of either crystal input. Each text box (Crystal 1 and Crystal 2) is editable by the user and is used to calculate the output frequency of each output. If a differential input is used for an external reference, check the Differential Input check box.
The reference input to each PLL is specified by using the various drop down menus shown in Figure 8.
Each PLL and REFOUT reference frequency can be supplied by Crystal 1, Crystal 2, or an external reference input Ref In. Crystal 2 and Ref In cannot be used simultaneously. The selection of Ref In or Crystal 2 is controlled by using the Ref In/Crystal 2 drop down.
The AD9578 evaluation software automatically configures the settings for each PLL based on user inputs for both the reference frequency and output frequency by using an internal frequency wizard and the Autocalculate button. To enable an output text box, change the appropriate logic level in each outputs allocated drop down menu. Logic levels are selectable from LVDS, LVPECL, HCSL, and LVCMOS. Once a text box is enabled, the user may enter the desired output frequency. Pressing Autocalculate will then calculate the value closest to the user input. Figure 9 shows a standard configuration in the software’s default mode using Output 1 and Output 3.
The OEx and override check boxes allow the user to manipulate the various output enable bits from the register 0x02 of the AD9578. Default operation is for both boxes to be checked, allowing the software to have control over each output.
Clicking the Advanced check box, as shown in Figure 7, expands the Main Window to allow the user to interact with individual PLL settings and the entire register map as the part is currently configured.
In Advanced Controls mode, all PLL feedback dividers, output dividers, charge pump and VCO settings are editable by typing in the various text boxes. It is recommended to allow the software to auto select the VCO band being used when in Advanced Controls mode. In this mode, all of the output frequencies are calculated based off the user’s settings for the reference frequencies and feedback/output division settings. The Autocalcuate feature is thus disabled in Advanced Controls mode. Another feature in Advanced Controls mode is the Reset Fuses Button. This button allows the user to reset the AD9578 to its default fuse blown settings without power cycling evaluation board. The default fuse blown settings are then displayed in the Main Window.
The Reference Output source is selected in the Input Frequency Section. The output frequency is displayed in the Reference Output section and the logic level is selectable from LVDS, LVPECL, HCSL, and LVCMOS.
When either PLL1 or PLL2 are in lock, the appropriate PLL lock indicator will turn blue.
The Comments box displays notifications to the user upon successful read/write operations as well as warnings when maximum limits of the part have been exceeded. Pressing the Clear Comments button erases all previous comments.
The AD9578 Frequency Wizard is responsible for calculating the optimum PLL settings for the user’s desired input and output frequencies when the Autocalculate feature is used. For any given frequency plan there may be multiple configurations possible for each PLL. The Frequency Wizard will automatically pick the best option by default, but every configuration can be accessed by pressing the Show Frequency Wizard button after Autocalculate has been pressed. The Frequency Wizard is shown in Figure 15.
Pressing the various Index buttons on the left of the window will load those particular settings into the Main Window and override the original settings chosen by the Frequency Wizard.
The File menu has the following options:
Select hardware is used to find and connect to an evaluation board that has been plugged in to the computer (or recently power cycled) after the evaluation software has already started.
Polling allows the software to automatically update the software without having to press the Read button. To disable Polling, uncheck the box shown in Figure 16.
Allows the user to load a previously created setup file into the software. Press the Configure button to load the setup file into the AD9578.
Creates a register setup file of the current settings seen in the evaluation board software. This setup file can be saved and used later by using Load All Registers.
Exits the program. This is the same function as the “X” icon in the upper right of the screen.
The View menu has the following options:
Allows the user to read write hex values to specific registers. The register address is selected in a drop down menu and the register value is written by the user. The Read button reads in the current register value at the address chosen the drop down. The Load button loads the setting in the Register Value text box into the register chosen in the drop down. The Debug Window expects register writes to be a hexadecimal number starting with “0x”.
Allows the user to alter the various XO settings found in registers 4 and 10. This is useful when configuring the part to use a different crystal value than what is originally placed on the board.
The Help Menu only contains the About section which shows a short summary of the software being used.