PCIM: Old ferrites get new life for GaN switching

GaN power transistors are giving new life to old ferrites as PSU designers seek magnetic components that can keep up with multi-MHz switching, according to Ferroxcube.

Ferroxcube 3F36 3F46 planar Ecore

“We are providing a lot of samples of 3F46 and 3F36 around the world,” the company’s product manager Artur Pawlak told Electronics Weekly at PCIM in Nuremberg.

A decade ago the firm created a class of fast ferrites, including the two above and even faster 4F1, but demand was low because few people needed the speed and Snoek’s law meant permeability was lower than in more sluggish materials.

Planar E-core parts (picture above) are the most popular, said Pawlak, because they work well with printed windings at GaN switching frequencies – the large surface-to-volume ratio gives good core cooling and exposed end-windings cool the coils.

TDK was another company showing core materials for GaN power supplies.

Its N59 was developed for operation from 700kHz to 2MHz, and it too was showing it in planar E-core for, although “N59 ferrite material is particularly suitable for transformers based on toroidal core topologies”, it said.

TDK Ecore triple gapSomething else on the TDK stand at PCIM was cores (in E, ETD, PM and PQ forms) with multiple air-gaps.

TDK Ecore single gapUp to 70% reduction in leakage field losses is claimed, or a reduction of one core size.


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