Decoupling Inductors used in SMPS

[thereza]

I'm working on a new board and picked an inductor for a switching regulator, but was surprised to find that it's a self-proclaimed "Decoupling Inductor".  What makes an inductor specially adapted to decoupling applications, and can I not use this for a sm power regulator (FT440).


http://www.tdk.co.jp/tefe02/e533_mlz_h.pdf

Reza

[Circlotron]

That datasheet lists inductors only going as high as 10 uH. That's not very big. Also they do not look like they have a "closed" magnetic circuit but instead let the flux exit one end of the inductor and find its way through the air to the other end. They would have some degree of HF filtering but not very suitable as an energy storage inductor like you want. These general type may be more suitable -> http://image.made-in-china.com/2f0j00rCStHivKfezO/SMD-Power-Inductors-SPRH127-.jpg

[thereza]

Great explanation - thanks.

Reza

[Ghydda]

What makes an inductor specially adapted to decoupling applications, and can I not use this for a sm power regulator (FT440).

Decoupling usually refers to ways of controlling/limiting EMI.
Inductors for decoupling usually needs to behave as an inductor at 10s and/or 100s of MHz.
Inductors for smps-purposes usually do not go much above a few MHz before stray capacitance takes over.