set_max_time_borrow - 2024.1 English

Vivado Design Suite Tcl Command Reference Guide (UG835)

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2024.1 English

Limit time borrowing for latches


set_max_time_borrow [‑quiet] [‑verbose] <delay> <objects>


Name Description
[-quiet] Ignore command errors
[-verbose] Suspend message limits during command execution
<delay> Delay value: Value >= 0
<objects> List of clocks, cells, data pins or clock pins




Sets the maximum amount of time in nanoseconds that can be borrowed between nets when analyzing the timing on latches.

Note: This command operates silently and does not return direct feedback of its operation.


-quiet - (Optional) Execute the command quietly, returning no messages from the command. The command also returns TCL_OK regardless of any errors encountered during execution.
Note: Any errors encountered on the command-line, while launching the command, will be returned. Only errors occurring inside the command will be trapped.
-verbose - (Optional) Temporarily override any message limits and return all messages from this command.
Note: Message limits can be defined with the set_msg_config command.

<delay> - (Required) The delay that should be applied to the specified objects. The <delay> is specified in nanoseconds (ns) as a floating point number >= 0, with a default value of 0.

<objects> - (Required) A list of clocks, cells, data pins, or clock pins to which the limit should be applied.


The following example specifies that the latches attached to "all clocks" will be allowed 0 time units of borrowing. Effectively, this disables time borrowing throughout the entire design.

set_max_time_borrow 0.0 [all_clocks]

The following example specifies that nets in the top level of hierarchy are allowed 20 time units of time borrowing:

set_max_time_borrow 20 {top/*}