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The prorating constraints, VOLTAGE and TEMPERATURE, provide a method for determining timing delay characteristics based on known environmental parameters. On a schematic, you can enter these constraints in any empty space. For Release 2.1i these two constraints are supported for XC4000XL/XLA. New speed file releases for existing architectures will support these two constraints.
Note: Prorating is not intended for military and industrial ranges. It is applicable only within the commercial ranges.
This constraint allows the specification of the operating voltage. This provides a means of prorating delay characteristics based on the specified voltage.
Note: Each architecture has its own specific range of supported voltages. If the entered voltage does not fall within the supported range, the constraint is ignored and an architecture-specific default value is used instead. The UCF syntax is as follows.
VOLTAGE=value[units]
value is an integer or real number specifying the voltage and units is an optional parameter specifying the unit of measure. V specifies volts, the default voltage unit.
This constraint allows the specification of the operating temperature which provides a means of prorating device delay characteristics based on the specified junction temperature. Prorating is a linear scaling operation on existing speed file delays and is applied globally to all delays.
Note: Each architecture has its own specific range of valid operating temperatures. If the entered temperature does not fall within the supported range, the constraint is ignored and an architecture-specific default value is used instead. The UCF syntax is as follows.
TEMPERATURE=value[C |F| K]
value is an integer or a real number specifying the temperature. C, K, and F are the temperature units: F is degrees Fahrenheit, K is degrees Kelvin, and C is degrees Celsius, the default.