Inductor Current rating vs Current saturation

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I know in theory what current saturation means, but when I am about to select an inductor on Digikey, I am not sure who these two parameters works together.

I am contemplating to buy something like
http://www.digikey.ca/product-de...
or
http://www.digikey.ca/product-de....

For one the saturation current is smaller than the current rating, for the one it is higher.

Could someone explain how these works ? Also if you can mention the resistance parameter better.

Thanks

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Current rating takes into account the gauge of the wire in the inductor. It does not insure that the inductor will have the required inductance at that current, just that the device will physically survive.

Saturation current is the current where the inductance drops to some specified level compared to its low current value. Pragmatically, what happens if you have current peaks that "bump" into the saturation zone, the inductor starts to get hot. If you keep normal current peaks to half of the saturation limit and worst case current peaks to 75%, you should be fine.

The resistance value is usually the DC resistance of the wire in the inductor. In some cases, it may be effective resistance as measured with a network analyzer; if it is this, then it will be a bit higher than the DC resistance because it would include core losses. You can usually tell if it is this because it will quote resistance at a particular test frequency.

Jim

Jim Wagner Oregon Research Electronics, Consulting Div. Tangent, OR, USA http://www.orelectronics.net

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Angelu,

In his description of a simple power inductor tester, Chan (actually his cat's name) illustrates the performance of various inductors with some sample screen captures such as that below.

I liked the idea so much I built one and have been using it recently in designing a switcher.

Cheers,

Ross

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Ross McKenzie ValuSoft Melbourne Australia