What is a high-current net constraint?
Quilter supports the definition of high current constraints to identify signals with elevated current requirements. These constraints enable Quilter to implement trace width controls with lower resistance, which can help prevent excessive voltage drops, IC brownouts, and overheating under load.
How do I create high current constraints?
High current constraints are defined in the "High-current Trace Controls" section of Circuit Comprehension during job creation.
High current constraints can be created in one of two ways:
Specifying a max current rating for an individual pin, net, or net class
Specifying a minimum trace width for an individual pin, net, or net class
You can choose from the following configuration options when defining a high-current constraint:
Name: Choose a name for your constraint rule that allows you to identify it
Scope: Choose the pins, nets, or net classes that you wish to apply the constraint to. You can use the "*" character for wildcard matching to apply the rule to all matching pins, nets, and net classes.
Value: Enter a numerical value and unit of measure. We currently support:
Trace widths in
mmormilsAmperages in
mAorA
All constraint rules that you have defined are added to the "Constraint Rules" table, where they can be viewed or deleted.
How does Quilter calculate trace widths for high-current nets?
Quilter uses the IPC-2221 Trace Width Calculator to calculate appropriate trace widths for high current constraints. This calculator takes the following variables as inputs:
Current rating: Defined by user
Temperature rise: We assume a default 20deg C temperature rise. We plan to make this user-configurable in the future.
External trace routing (top and bottom layers)
Copper weight: Quilter's stack-ups utilize 1oz copper
FAQs
What is the maximum current Quilter can handle?
Quilter can reasonably handle signals up to 4A. Because Quilter cannot meet high-current constraint requirements with copper pours, we do not recommend that users generate boards with >4A using Quilter at this time.
How does Quilter validate high-current nets?
Quilter validates differential pairs using Physics Rule Checks. More information on PRCs for differential pairs can be found here.