Specifying the Maximum Transition Constraint

Maximum transition constraints can come from a user input, library, and library pin. User-specified maximum transition constraints are expressed with the main library derate and slew threshold of PrimeTime.  The set_max_transition command sets a maximum limit on the transition time for all specified pins, ports, designs, or clocks. When specified on clocks, pins in the clock domain are constrained. Within a clock domain, you can optionally restrict the constraint further to only clock paths or data paths, and to only rising or falling transitions. During constraint checking on a pin or port, the most restrictive constraint specified on a design, pin, port, clock ( if the pin or port is in that clock domain), or library is considered. This is also true where multiple clocks launch the same path.
The set_max_transition command places the max_transition attribute, which is a design rule constraint, on a specified objects. In Prime Time, the slews and maximum transition constraint attributes are reported in the local threshold and derate of each pin or library.

To view the maximum transition constraint evaluations, use the report_constraint -max_transition cmd.  Prime Time reports all constraints and slews in the threshold and derate of the pin of the cell instance, and the violations are sorted on the absolute values ( that is, they are expressed in that of design threshold and derate ). You can also use the report_constraint command to report constraint calculations only for maimum capacitance and maximum transition for a specified port or pin list. Use the object_list option to specify a list of pins or ports in the current design that you want to display constraint related information.

To see the port maximum transition limit, sue the report_port -design_rule command. To see the default maximum transition setting for the current design, sue the report_design command. To undo maximum transition limits previously set on ports , pins, designs, or clocks, use remove_max_transition.

setting a maximum transition limit.
To set a maximum transition limit of 2.0 units on the ports of OUT*, enter
pt_shell> set_max_transition 2.0 [get_ports "OUT*"]

To set the default maximum transition limit of 5.0 units on the current design, enter
pt_shell> set_max_transition 5.0 [current_design]

To set the maximum transition limit of 4.0 on all pins in the CLK1 clock domain , for rising transitions in data paths only, enter
pt_shell> set_max_transition 4.0 [get_clocks CLK1] -data_path -rise