User`s guide

Timin

Characteristics 7

-13

DIGMNTYSCALE

This option computes the minimum delay when a typical delay

is known, using the formula:

TPxxMN = DIGMNTYSCALE ⋅ TPxxTY

DIGMNTYSCALE defaults to the value 0.4, or 40% of the

typical delay. Its value must be between 0.0 and 1.0.

DIGTYMXSCALE

This option computes the maximum delay from a typical delay,

using the formula

TPxxMX = DIGTYMXSCALE ⋅ TPxxTY

DIGTYMXSCALE defaults to the value 1.6. Its value must be

greater than 1.0.

When a typical delay is unspecified, its value is derived from the

minimum and/or maximum delays, in one of the following

ways. If both the minimum and maximum delays are known, the

typical delay is the average of these two values. If only the

minimum delay is known, the typical delay is derived using the

value of the DIGMNTYSCALE option. Likewise, if only the

maximum delay is specified, the typical delay is derived using

DIGTYMXSCALE. Obviously, if no values are specified, all

three delays will default to zero.

Treatment of unspecified timin

constraints

The remaining timing constraint parameters are handled

differently than the propagation delays. Often, data books state

pulse widths, setup times, and hold times as a minimum value.

These parameters do not lend themselves to the extrapolation

method used for propagation delays.