Specifying Timing Constraints and Exceptions (TimeQuest Timing Analyzer)


Timing constraints and exceptions allow you to specify the timing conditions for proper operation of your design. You must fully constrain your design for the TimeQuest Timing Analyzer to produce an accurate timing analysis. The TimeQuest analyzer verifies that your design meets all specified timing constraints and reports the results in the Report pane and the Console. The Fitter uses timing constraint information to optimize placement of the design in the target device.

You can specify all timing constraints in Synopsys Design Constraints (SDC) format using the graphical user interface (GUI), by entering the constraints directly in the Console, or by creating or editing an SDC File in the Quartus II Text Editor. The SDC File should contain only SDC statements from the quartus::sdc or quartus::sdc_ext packages.

The TimeQuest analyzer supports constraints that allow you to define the timing conditions for your design, such as clock constraints, clock latency, and input and output delays. Timing exceptions allow you to modify the default timing analysis rules for specific paths, such as multicycle paths, false paths, and minimum and maximum delays.

The following sections describe how to specify constraints and exceptions for TimeQuest analysis.


Important: You must create the timing netlist by using the Create Timing Netlist command before you can specify timing constraints.


Clock Constraints

ExpandTo  define a clock:

ExpandTo define a generated clock:

ExpandTo set clock latency:

ExpandTo set clock uncertainty:

ExpandTo cut clocks by setting a clock group:

ExpandTo remove a clock:


Input and Output Constraints

ExpandTo set input delay:

ExpandTo set output delay:


Derivation Constraints

ExpandTo derive PLL clocks:

ExpandTo derive clock uncertainty:


Timing Exceptions

ExpandTo define a false path:

ExpandTo define a multicycle path:

ExpandTo set maximum delay:

ExpandTo set minimum delay:



Important: When you specify constraints and exceptions, you must use the Write SDC File command to save them to the SDC File.



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