Hi,
It depends which version you have. There have been several iterations of the eval board which made various changes and improvements. There are two quick methods to determine which you have.
You can open WaveVision and see what FPGA image is being loaded. It is displayed once at startup and all the time at the top of the window (shown below).
Here I'm showing version 2 of the board. ADC12D1600RB2. We can use this number to determine which clock is installed.
Or you can also inspect the board and read the top side mark of the clock device directly shown below.
You can enter this information into the part marking tool which will translate it to the corresponding device: http://focus.ti.com/general/docs/partmarking/partmarkinghome.jsp
The two clocking devices we have used are the LMX2531LQ1778E or the LMX2541SQ3740E.
The available VCO frequencies are limited to the following:
Clocking Device | VCO Frequency (MHz) |
LMX2531LQ1778E | 1726 – 1840 |
LMX2541SQ3740E | 3480 – 4000 |
The LMX2531 is run at 1800MHz and outputs the VCO directly. It has the option to use the output divider of /1 or /2. If this is the version you have then you cannot output 1200MHz.
The LMX2541 is run at 3600MHz and uses the output divider to get 1800MHz. The output divider has a much greater range, /1 to /63. We currently use /2 to get 1800MHz. If you use /3 you can get to 1200MHz.
Note that you cannot program the clock directly from the WaveVision GUI though. You will either need to modify the XML script file and/or FPGA image or you will need to use an external microcontroller like USB2ANY and connect it directly to the SPI bus and program using CodeLoader.
An easier method is to configure the board for external clock and connect a 1200MHz clock source directly. Again depending on which version of the board you can either change it directly in WaveVision, or it may require a resistor change in addition to setting it in WaveVision. Please refer to the following thread: http://e2e.ti.com/support/data_converters/high_speed_data_converters/f/68/p/304442/1060429.aspx#1060429
Let me know how it goes!