# Effect of Isat on inductor when connecting four inductors in a combination

In my circuit I want to use inductor having value 330uH. So instead of connecting a single inductor, I prefer to connect 4 inductors, two of them in series two make it 660uH and another two in parallel with the last two of them to make it again 330uH. This is it if we are talking about only inductance but waht about saturation current. Using this connection how it would affect the saturation current of the indductors? Will I actually get 2 x 4amp = 8amp Isat? For a little bit of time, consider this one as a cheaper than using a single inductor. What are the pros and cons for doing this??

• Not that I don't like my answer being accepted, but you might get more (and better?) answers if you wait at least two days until you accept. Aug 13, 2013 at 6:39
• @zebonaut No actually I found very reasonable explanation the link you have provided. Its good and doesn't create any choasity.But if you said then I wait untik the another good and accepted answer. Well +1 for suggesting me the links
– Atom
Aug 13, 2013 at 6:59

If the saturation current of a single 330uH inductor is 2A, then having two in series will still saturate at 2A.

Having two series strings in parallel means the strings as individuals will saturate at 2A but because they are in parallel the circuit combination will saturate at 4A.

Make sure they are not closely coupled or the inductance values will change due to coupling magnetic fields to each other.

• So using this combination can I change the limiting value of Isat?
– Atom
Aug 13, 2013 at 7:20
• @SHASWAT using 4 series / parallel inductors of 2A Isat will yield an overall 4A Isat Aug 13, 2013 at 7:21
• Possibility of any other problem (e.g. magnetic interfernece) or any other issue using this combination?
– Atom
Aug 13, 2013 at 7:25
• @SHASWAT If they are close to each other on the circuit board they may cause the overall inductance to rise due to mutual coupling. Aug 13, 2013 at 8:03

The saturation current is a constant for a given inductor. Just like the "normal" current will be shared between two paralleled inductors depending on their value, this "normal" current will just reach the point of saturation. In Theory, two parallel inductors can take twice the (saturation) current of one induvidual inductor. No big deal here. For series-connected inductors, it's a bit like the chain analogon: The chain breaks once the weakest link breaks. The behavior of two series-connected inductors is covered here.

Your setup of a series connection of two paralleled inductors each will have twice the saturation current compared to the value you find in one inductor's data sheet.

However, you will likely end up having your four paralleled and series-connected inductors close to each other. Depending on the type of core and the stray field your cores will create, your four inductors might become coupled to a certain degree, with the overall inductance not being what you expect. See here for more info on this issue.

• Thanxx for the link. This is what I want to know.
– Atom
Aug 13, 2013 at 5:59