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.

Content:

• Definition of operating voltage
• Effects of exceeding the operating voltage
• Molded inductors
• Test method

Download: ANP126