Somewhere in the last few years, chargers quietly shrank. A 65-watt charging block that used to take up half an outlet strip now fits next to your keys. The battery inside your phone didn't get this upgrade, the semiconductor switching the power did.

The transformer is the problem

A charger's job is to take wall power and step it down to something your device can use, and it does this by switching the incoming power on and off at high frequency through a small transformer, thousands to millions of times a second. The faster you can switch, the smaller the transformer and supporting coils can be — size scales down roughly in proportion to frequency.

The limiting factor has always been the switching transistor. Ordinary silicon MOSFETs lose more energy as heat the faster you switch them, and that heat has to go somewhere — usually a bigger heatsink and a bigger enclosure to dissipate it safely. For decades, that tradeoff capped how small a charger could get at a given wattage.

A wider bandgap changes the math

Gallium nitride (GaN) is a wide-bandgap semiconductor, which in practice means it can switch far faster than silicon while wasting much less energy doing it. Higher switching frequency lets the transformer and inductors shrink dramatically; lower switching losses mean less heat, which means a smaller enclosure and a smaller (or absent) heatsink. Both effects push in the same direction: less silicon-era bulk, for the same or higher wattage.

That's the whole story behind the wave of tiny 65W and 100W GaN chargers that showed up on charging blocks over the past few years — not a new battery trick, a better switch.

Worth being precise here too, same way the SiC/Si-C mix-up comes up in battery anodes: gallium nitride and silicon carbide (SiC) are both wide-bandgap semiconductors, but they specialize differently. SiC tends to win at higher voltages and power levels — EV inverters, industrial drives. GaN tends to win at higher frequencies and lower-to-mid power — chargers, power supplies, RF amplifiers. Related chemistry, different jobs.

Not just smaller — cooler and cheaper to run

Lower switching losses mean a GaN charger wastes less power as heat for the same job, which matters more at scale than it sounds: a data center's worth of power supplies running a percent or two more efficiently adds up fast. On your desk it just means the brick barely gets warm anymore.

What to watch

  • Prices keep dropping as GaN fabrication scales — it was a premium feature a few years ago, now it's showing up in budget chargers.
  • Multi-port chargers pushing higher combined wattages (100W+) without getting bigger, since GaN is what makes splitting power across ports efficiently practical.
  • GaN creeping into laptop power supplies and eventually server/data-center power delivery, where the efficiency gain matters even more than the size.

Same pattern as the anode story: not a flashy headline feature, just a components-level swap that quietly makes everything around it smaller, cooler, and a little more efficient.