Controlling Power Consumption

The power consumption of each macrocell in an CPLD device is programmable. The standard (default) setting consumes more power and produces shorter propagation delay. The low-power setting reduces power consumption for less speed-critical paths.

By default, all macrocells in the design will operate in standard power mode. You can change the global power setting to use the low power mode throughout the design by selecting Low on the Default Power Setting in the Implementation Options template in the Design Manager:

1. Design Implement
   
   
2. Press the Options softkey.
   
   
3. Select Edit Template
   
   
4. Select the Basic tab.
   
   
5. Select the Low option adjacent to Macrocell Power Setting.
   
   

When you run the fitter your design will be implemented with the low power setting.

To specify low power when using the Unix command line, use the "lowpwr" parameter with the cpld command as follows:

cpld -lowpwr design_name

You can also instruct the fitter to automatically reduce the macrocell power for paths that do not require standard power to meet timing constraints. In the Design Manager, check Timing Driven. On the Unix command line, specify the -autopwrslew parameter on the cpld command line:

cpld -autopwrslew design_name