Beyond Design: High-speed Rules of Thumb
Global PCB Connections: A Technical Overview of Long-flex Printed Circuit Boards
The Shaughnessy Report: A Handy Look at Rules of Thumb
Estimated reading time: Less than a minute
Trace Currents and Temperature, Part 3: Fusing Currents
One day, after I gave a seminar on trace currents and temperatures, a student asked me: "I have a trace that only needs to be able to carry 20 amps for 0.5 seconds. After that, I don’t care what happens to it. How do I determine how big the trace needs to be?"
There are certain applications where such a requirement is quite reasonable. Consider, for example, a trace that normally carries a reasonable current. But if there is a catastrophic system failure, the trace would be subject to a very large current. If such a failure occurs, you may need to have the time necessary to shut down the system in a controlled manner--perhaps to prevent even more catastrophic failures, or to prevent the chance of human injury, etc. There are at least three ways to address this type of problem.Read the full article here.This column originally appeared in the January 2013 issue of The PCB Design Magazine.
Share on:
More Columns from Brooks' Bits
Brooks' Bits: Internal Trace Temperatures—More Complicated Than You ThinkBrooks' Bits: Electromagnetic Fields, Part 3 - How They Impact Coupling
Brooks' Bits: Electromagnetic Fields, Part 2: How They Impact Propagation Speed
Brooks' Bits: How Electromagnetic Fields Determine Impedance, Part 1
Trace Currents and Temperature, Part 4: Via Heat
Trace Currents and Temperature, Part 1: The Basic Model
The Skinny on Skin Effect, Part 3: Crossover Frequency
Brooks' Bits: The Skinny on Skin Effect, Part 2