The Primary Magnetic Materials for
Output Chokes / Inductors / Smoothing Chokes:
Gapped Ferrite Cores
Cut Nanocrystalline Toroids
A Diagram Showing How the Materials Relate
Between Frequency and Flux Density:
To aide in selection of material, please see the discussion below:
Prevalent material is gapped ferrite. The usual requirement for DC-DC converters is lowest possible losses for highest possible efficiency.TDK’s PC90 material is the best material for this application with the Epcos N92 as an alternative.
The wide variety of topologies have different demands on the magnetics. Some converters require the highest possible saturation point so that Sendust or MegaFlux is the preferred material. Other converters are more sensitive to core losses so that gapped ferrite or cut Nanoperm is the better choice of material. Converters operating with a switching frequency over (about) 150KHz perfer gapped ferrite since the eddy current losses can be high.
The material of choice has historically been MegaFlux due to it’s Mega high saturation point and energy storage. Only in specific cases where efficient is critical does a gapped ferrite make sense. This usual takes place in a solar inverter where efficiency is critical.