The AD9508 evaluation board is a compact, easy-to-use platform for evaluating all features of the AD9508. This user guide focuses on the AD9508 evaluation board and software. The AD9508 is a high performance 1:4 flexible clock buffer. Each output has a programmable divider that can be set via SPI/I2C programming or Sx pin strapping. The AD9508 features both 2.5 V and 3.3 V operation. For convenience, detailed information from the AD9508 data sheet has been included in this user guide. Use this guide in conjunction with the AD9508 data sheet and software documentation available at www.analog.com.
The following instructions are for setting up the physical connections to the AD9508/PCBZ evaluation board. Before connecting the evaluation board to a PC for the first time, the user must install the evaluation software.
To connect signals, connect a signal generator to the J200 (CLKIN) SMA connector. By default, the CLKIN input is connected to a balun for single-ended to differential conversion. This path is differentially terminated to 100 Ω and ac-coupled into the AD9508 reference inputs. An amplitude setting of 0 dBm to 6 dBm is fine. The CLKIN_B SMA input is grounded by default. To input a differential signal, the user must remove Balun T200 and Resistor R221, and replace Resistors R209 and R210 with 0 Ω. Connect an oscilloscope, spectrum analyzer, or other lab equipment to any of the J209 to J216 SMA clock OUTx connectors on the edge of the board. OUT0 through OUT3 are ac-coupled outputs differentially terminated to 100 Ω.
Table 1. P102, P106, P110, and P114 Jumper Settings with Respect to Jumper P101 Setting
|Programming Pin||Jumper Placement vs. Programming Method (SPI or I2C)||Pin Strapping|
|S0||P102 = SCLK||P102 = S0P|
|S1||P106 = SDIO||P106 = S1P|
|S2||P110 =||P110 = S2P|
|S3||P114 = SDO||P114 = S3P|
There are two more jumpers allocated for each Sx pin that are used to obtain all eight divider settings (for Pin S0 through Pin S3) and to select between logic types (Pin S4 and Pin S5). The first jumper is used to pull the Sx pin up to VDD or down to GND. The second jumper is used to select one of the four resistor settings on the evaluation board. Table 2 describes the possible divider and output mode settings when in Sx pin programming mode. Table 3 lists the jumper label associated with each divider ratio and driver mode setting.
Table 2. Divider Ratio and Driver Mode Table for S0, S1, S2, S3, S4, and S5 Pins (Driver Modes Are Listed in the Order of CH1/CH2 or CH3/CH4)
|Programming Pins||Sx Pin Settings (0 Through 7) vs. Resistor Value vs. Divide Value and Logic Type||Description|
|0 = 820 Ω Pulled to GND||1 = 1.8 kΩ Pulled to GND||2 = 3.9 kΩ Pulled to GND||3 = 8.2 kΩ Pulled to GND||4 = 820 Ω Pulled to VDD||5 = 1.8 kΩ Pulled to VDD||6 = 3.9 kΩ Pulled to VDD||7 = 8.2 kΩ Pulled to VDD|
|S0||÷1||÷2||÷3||÷4||÷5||÷6||÷8||÷16||S0 is assigned to the CH0 divider ratio only|
|S1||÷1||÷2||÷3||÷4||÷5||÷6||÷8||÷16||S1 is assigned to the CH1 divider ratio only|
|S2||÷1||÷2||÷3||÷4||÷5||÷6||÷8||÷16||S2 is assigned to the CH2 divider ratio only|
|S3||÷1||÷2||÷3||÷4||÷5||÷6||÷8||÷16||S3 is assigned to the CH3 divider ratio only|
|S4||HSTL/HSTL||HSTL/LVDS||HSTL/ Disable||LVDS/HSTL||LVDS/ LVDS||LVDS/ Disable||Disable/ HSTL||Disable/ Disable||S4 is assigned to CH0/CH1 to select their output logic types|
|S5||HSTL/HSTL||HSTL/LVDS||HSTL/ Disable||LVDS/HSTL||LVDS/ LVDS||LVDS/ Disable||Disable/ HSTL||Disable/ Disable||S5 is assigned to CH2/CH3 to select their output logic types|
Table 3. Evaluation Board Sx Pin Jumper Labels
|Programming Pins||Evaluation Board Sx Pin Jumper Labels|
|820 Ω/1.8 kΩ||3.9 kΩ/8.2 kΩ||Pull Up to VDD/Pull Down to GND|
The AD9508 evaluation software allows the user to control the full functionality of the AD9508 through SPI/I2C communication on the evaluation board. Use the following instructions to set up the evaluation board software.
Do not connect the evaluation board 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.
The bottom left corner of the main window should now display AD9508 Evaluation Board in green. Alternatively, you can use the software in standalone mode. The standalone mode is useful for verifying register settings for a given setup. See the Evaluation Software Components section for a description of the evaluation software features.
The AD9508 evaluation software is composed of subsections that correspond to the major functional blocks of the AD9508. These subsections are described in the following sections of the user guide. Some of the subsections have dedicated windows that allows the user to edit the register settings associated with a functional block. For example, the output distribution functional block window can be accessed by clicking the DIST REGISTER button. Some of the functional blocks have editable text areas that can be accessed and altered without opening each functional block window. Altering these text areas changes the settings found in the various block windows and immediately loads the change into the evaluation board. Conversely, edits to the settings within a block are reflected in the respective text area.
After clicking Load, the settings from that subwindow are loaded to the evaluation board. When editing a text box within the main window, the ENTER key must be pressed before a change is saved and loaded into the evaluation board.
The input receiver (INPUT RECV) section allows the user to select between single-ended and differential operation. Click the mux symbol within the block to highlight the active path (see Figure 5). The left image in Figure 5 shows the default differential operation of the input receiver. The right image shows single-ended operation.
The output distribution (OUTPUT DIST) section allows the user to alter divide ratios and phase offsets for each output of the AD9508. Each divide and phase block can be edited by typing the preferred value within the block, and then pressing the ENTER key. When ENTER is pressed, the values are loaded into the evaluation board. The phase offset blocks accept the u (micro), p (pico), and n (nano) prefixes. Phase offset is limited to one half of the period of the input clock rate. Each divider supports integer divide values from 1 to 1024. If the typed value is not achievable in the current configuration, the software automatically rounds to the nearest possible solution. The output distribution section is shown in Figure 6.
Clicking the DIST REGISTERS button at the bottom of the output distribution section allows the user to access all of the distribution register settings in the Distribution Settings window (see Figure 7).
The Distribution Settings window consists of four individual tabs for each output channel. Each tab contains controls for each channel divide ratio, phase offset, driver mode, polarity and power-down settings. To load any of the settings to the evaluation board changed within the Distribution Settings window, the user must click the Load button.
The driver mode and polarity settings are altered by selecting one of the values from the respective drop-down box and clicking the Load button. To power down a channel driver, the appropriate channel power-down box must be selected.
The Operational Controls window is opened by clicking the CONTROL button at the bottom of the main window. This window contains controls for SPI configuration, LDO voltage control, channel power-down, sleep mode, and two buttons for soft reset and soft sync. The Operational Controls window is shown in Figure 8.
The Register Map window is accessed by clicking the REG MAP button at the bottom of the main window. Figure 9 shows the Register Map window.
The Register Map window contains two tabs. The All tab displays all of the registers that can be changed through the AD9508 evaluation software. Each register can be selected by clicking the various blue boxes shown in Figure 9. Register details for the selected register appear at the bottom of the window. These details include the name of the register, the current register value, and the various bit fields for the register. The Changed tab contains all of the registers that have been modified from within the AD9508 evaluation software but not loaded into the evaluation board yet. These same registers are also highlighted in the All tab as they are modified.
The READ ALL and WRITE ALL buttons are located at the bottom of the main window. Click the READ ALL button to read all of the register values currently stored in the chip and transfer them to the evaluation software. Click the WRITE ALL button to transfer all of the register values currently loaded into the software and write them to the chip.
The Reset Button is located at the bottom of the main window. Clicking this button resets the part to its default register settings, which is also reflected in the main window.
Click the SYNC button to issue a soft synchronization command, which synchronizes all outputs that are not omitted by the appropriate SYNCMASKx bit. Refer to the AD9508 data sheet for more information about the sync command.
The File menu includes the following options:
The AD9508 evaluation system allows one PC to control multiple evaluation boards. This window allows the user to select the evaluation board that the software is controlling. Click the Refresh button to detect a recently connected evaluation board.
Polling allows the user to define how often the software checks for changes made to the register values on the AD9508. Polling also checks for a hardware connection, which updates in the lower left corner of the main window. The polling interval window sets the length of time between each software check. The default interval is 1 sec. Figure 12 shows the polling interval selection window.
Exits the evaluation software. No checking is performed to ensure that the existing setup is saved.
The View menu includes the following options:
The Debug window allows the user to read the values that are loaded into the various register addresses as well as manually load values into each register address of the AD9508 on the evaluation board. Figure 13 shows the Debug Window. Detailed information about the usable registers and their functions can be found in the AD9508 data sheet.
Selecting About opens the AD9508 window, which contains information about the version of the evaluation board software.
I2C refers to a communications protocol originally developed by Philips Semiconductors (now NXP Semiconductors).