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28 DESIGN007 MAGAZINE I OCTOBER 2025 depends on context. "High" can mean above 100 watts in consumer electronics, but just a few watts is considered high power in RF. High power in EVs might mean hundreds of kilowatts, or hundreds of megawatts in industrial systems. In practice, high power begins when heat must be actively man- aged, insulation distances must be calculated, and failures pose real safety risks. It's the point where the physics of heat, fields, and safety dominate the design, and in autonomous vehicles, it is the invis- ible backbone that makes autonomy possible. A design engineer, when thinking of high power, told me he means that "this is the point where physics stops being polite and starts getting real." But actually, when you look at high power vs. high speed, the laws of physics don't change as we move from a 3.3-volt trace to an 800-volt bus. Maxwell's equations, Ohm's law, and Joule heating are exactly the same equations we learn in the first semester of electrical engineering. What does change is how dominant those effects become once the voltages and currents rise. At low power, parasitics are background noise. A few nanohenries of inductance or a fraction of an ohm in a trace hardly matter. A slight temperature rise can be ignored. A layout shortcut rarely causes more than minor performance issues. In short, the physics is there, but it behaves politely. But with high power, those same "small" effects become the main character in the movie. A few nanohenries of inductance can cause destructive voltage spikes. A few milliohms of resistance can translate into significant heating. A sharp copper corner or a contaminated board surface can lead to partial discharge or arcing. The physics has not changed, but the consequences have scaled up dramatically. That's why high power is both fascinating and intimidating. It forces designers to confront the same basic rules of electricity and magnetism, but at a scale where the margins are thin, the by-prod- ucts are unavoidable, and the cost of ignoring them is no longer a glitch but a failure that can take down the entire system. DESIGN007 John Watson is a professor at Palomar College, San Marcos, California. To read past columns, click here. E L E M E N TA RY, M R . WATS O N That's why high power is both fascinating and intimidating. " "