3.7. Clock Worksheet
Intel FPGA devices support global, regional, or periphery clock networks. The EPE spreadsheet does not distinguish between global or regional clocks because the difference in power is not significant.
Each row in the Clock worksheet of the EPE spreadsheet represents a clock network or a separate clock domain. Enter the following parameters for each design module:
- Clock frequency (in MHz)
- Total fanout for each clock network used
- Global clock enable percentage
- Local clock enable percentage
|Domain||Specify a name for the clock network in this column. This is an optional value.|
|Clock Freq (MHz)||Enter the frequency of the clock domain. This value is limited by the maximum frequency specification for the device family.|
|Total Fanout||Enter the total number of flipflops and RAM, DSP, and I/O blocks fed by this clock. The number of resources driven by every global clock and regional clock signal is reported in the Fan-out column of the Quartus II Compilation Report. In the Compilation Report, select Fitter and click Resources Section. Select Global and Other Fast Signals and click Fan-out.|
|Global Enable %||Enter the average percentage of time that the entire clock tree is enabled. Each global clock buffer has an enable signal that you can use to dynamically shut down the entire clock tree.|
|Local Enable %||
Enter the average percentage of time that clock enable is high for destination flipflops.
Local clock enables for flipflops in ALMs are promoted to LAB-wide signals. When a given flipflop is disabled, the LAB-wide is clock disabled, cutting clock power and the power for down-stream logic. This worksheet models only the impact on clock tree power.
|Total Power (W)||This is the total power dissipation due to clock distribution (in watts). This value is automatically calculated.|
|User Comments||Enter any comments. This is an optional entry.|
For more information about the clock networks of the supported device families, refer to the “Clock Networks and PLLs” chapter of the respective device handbook.
Did you find the information on this page useful?