Relationship to Other Clock Settings

Allows you specify the timing requirements for an "absolute" clock (not dependent on other clocks), and/or to define the relationship between an absolute and "derived" clock (dependent on another clock) in your project. You can specify the timing requirements for an absolute clock and define its relationship with a derived clock with one or more of the following options and/or settings:

Independent of other clock settings Specifies that the current clock settings are for an absolute clock, not dependent on any other clocks.

Required fmax Specifies the minimum acceptable f_MAX requirement for the current absolute clock settings. You can select Independent of other clock settings, type a value in the box, and select a time unit in the list to indicate the minimum speed at which the clock must run to latch all internal signals. This requirement overrides the default required f_max for the specified clock signal.

Resulting period Displays the resulting clock period of the current absolute clock settings.

Duty Cycle Specifies the percentage of time that the clock period is high. For example, an 80% duty cycle on a 10 ns clock indicates that every 10 ns, the clock is high for 8 ns and low for 2 ns. You can specify a numeric value in the Duty Cycle box to specify the required duty cycle of an absolute clock.

Include external delays to and from device pins in fmax calculations Specifies that f_MAX calculations, for the clock to which the settings are assigned, should include external delays to and from device pins. You can turn on this option to include pin-to-pin delays when the Timing Analyzer calculates the minimum speed the clock must run to latch all signals.

Based on Allows you to specify the relationship and requirements for a derived clock that is based on the absolute clock settings you select in the list.

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Independent of other clock settings	Specifies that the current clock settings are for an absolute clock, not dependent on any other clocks.
Required fmax	Specifies the minimum acceptable f_MAX requirement for the current absolute clock settings. You can select Independent of other clock settings, type a value in the box, and select a time unit in the list to indicate the minimum speed at which the clock must run to latch all internal signals. This requirement overrides the default required f_max for the specified clock signal.
Resulting period	Displays the resulting clock period of the current absolute clock settings.
Duty Cycle	Specifies the percentage of time that the clock period is high. For example, an 80% duty cycle on a 10 ns clock indicates that every 10 ns, the clock is high for 8 ns and low for 2 ns. You can specify a numeric value in the Duty Cycle box to specify the required duty cycle of an absolute clock.
Include external delays to and from device pins in fmax calculations	Specifies that f_MAX calculations, for the clock to which the settings are assigned, should include external delays to and from device pins. You can turn on this option to include pin-to-pin delays when the Timing Analyzer calculates the minimum speed the clock must run to latch all signals.
Based on	Allows you to specify the relationship and requirements for a derived clock that is based on the absolute clock settings you select in the list.