User`s guide

Creatin
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a Di
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ital Model Usin
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the PINDLY and LOGICEXP Primitives 7
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delay in every CASE function. Also note that the expressions
must be separated by a comma.
In the PINDLY section of the PINDLY primitive in the model
listing, the four output nodes (QA_O through QD_O) all use the
same delay rules. The CASE function is evaluated
independently for each of the outputs in turn. The first delay
expression is:
CLOCK & LOADBAR=='1 & TRN_LH, DELAY(-1,13NS,20NS)
This means that if CLOCK is TRUE, and LOADBAR is equal
to 1, and QA_O is transitioning from 0 to 1, then the values of -
1, 13ns, and 20ns are used for the MINIMUM, TYPICAL, and
MAXIMUM propagation delay for the CLK-to-QA data output
of the chip. In this case, the manufacturer did not supply a
minimum prop delay, so we used the value -1 to tell the
simulator to derive a value from what was given. If this
statement is TRUE, then the simulator assigns the values and
move on to the CASE function for QB_O and eventually
RCO_O.
For instances where one or more propagation delay parameters
are not supplied by the data sheet, the simulator derives a value
from what is known and the values specified for the .OPTION
DIGMNTYSCALE and DIGTYMXSCALE.
When the typical value for a delay parameter is known but the
minimum is not, the simulator uses the formula:
TPxxMN = DIGMNTYSCALE X TPxxTY
where the value of DIGMNTYSCALE is between 0.1 and 1.0
with the default value being 0.4. If the typical is known and the
maximum is not, then the simulator uses the formula:
TPxxMX = DIGTYMXSCALE X TPxxTY
where the value of DIGTYMXSCALE is greater than 1.0 with
the default being 1.6. If the typical value is not known, and both
the minimum and maximum are, then the typical value used by
the simulator will be the average of the minimum and maximum
propagation delays. If only one of min or max is known, then the
typical delay is calculated using the appropriate formula as
listed above. If all three are unknown, then they all default to a
value of 0.