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  • Automatic Detection
  • Recommended Patterns
  • Defaults
  • Constraint details
  • Physics Rule Checks

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  1. Routing Constraints

High Current Nets

Explanation of Quilter’s High Current Net constraint, including automatic detection criteria, recommended naming conventions, default current values, and IPC-based validation methods.

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Last updated 10 days ago

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This constraint aims to establish the minimum trace widths needed to prevent excessive resistive heating on traces carrying high currents.

Automatic Detection

Nets with certain attributes will be automatically classified as high current nets. This will include:

  • Any net that matches our various patterns for being a voltage or power net.

  • Any net in a "Power" netclass.

Recommended Patterns

You can force Quilter to detect a high current net by placing it in a "Power" net class. This is particularly helpful for nets that do not have a voltage-pattern name (like 3V3) but do need to carry a significant amount of current, such as a net that powers a motor.

Defaults

We assign conservative default values to every automatically detected net, assuming they are unlikely to carry high current. If a net is expected to encounter a substantial amount of current, you should specify the maximum in the interface.

Nets with detected voltages under 3V are assigned a 200mA maximum current by default, and nets over 3V receive a maximum of 500mA.

Constraint details

High current nets can be set up in the "High Current Nets" section of Circuit Comprehension. You can add them one by one, match them with regex, or use a netclass.

To define a high current net constraint, you'll need to fill in the following fields:

  1. Net name

  2. Maximum current (mA)

Quilter automatically completes IPC calculations that consider the specified copper weight and layer thickness for each stack-up to determine the ideal trace width for the net to prevent overheating.

Physics Rule Checks

The PRCs that validate this constraint after compilation are:

Overheated Length determines the approximate analytic temperature rise of trace segments on a specified high current nets. A net segment is considered “overheated” if its approximated temperature rise exceeds 20C.