Might as well post this here as well : Wurth Elektronik has a lot of useful books and application notes.
It is not really a book, it is a technical article over the dielectric strength molded inductors need to have.
Making the perfect inductor with the perfect core in combination with fast GaN mosfets causes for high voltage spikes and therefor dv/dt issues.
The perfect molded inductor isolating layers can break down when used optimal but no care is considered about voltage spikes.
Interesting subject. Better components and all of a sudden physical properties that never where really an issue can now become an issue when selecting the wrong kind of inductor.
Now with current (MHz switching) SMPS technology the isolation strength of an molded inductor has to be taken into account as well.
ANP126
www.we-online.com
ANP126 | Voltage specification for molded inductors
Excerpt from text:
"
With the continuous technological advancement in the semiconductor industry, MOSFETs today can achieve high power densities and fast switching speeds. For this reason, the question of the dielectric strength of inductors has become very important in recent years when selecting the right inductor and will continue to be a requirement to be considered in the future.
With the increasing popularity of molded inductors based on fine iron powder with a distributed air gap also the production process has changed in recent years. By constantly optimizing the production process and the material composition, it is possible to achieve the greatest possible permeability, in order to realize large inductance values in the smallest possible installation space. This must be combined with the maximum possible current carrying capacity. As a result, the power density per volume can be continuously increased. To constantly increase the power handling of the inductors in the smallest possible volume, the percentage of insulation binder in relation to the iron powder has been continuously reduced so that, consequently, the distance between the individual grain sizes has continuously decreased. This reduction has resulted in the fact that today, the applied voltages to an inductor within a DC-DC converter should be considered when selecting an inductor for an application and thus a high operating voltage can lead to failure of the entire application.
To ensure transparency, Würth Elektronik has developed a concept that tests the behavior of the component at higher voltages close to the application over a longer period in order to integrate the new property for molded inductors into the data sheets.
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