Physical Size of the Inductor

[shemo]

I saw two inductors on a board, L1 is much bigger than L2. L1 specified as 2uH on top, whereas L2 has 220 which I assume is 220uH.

The smaller physical sized inductor has bigger value. I assume that's true.

I have seen giant coiled inductor in the power supply,can I assume they would have low inductance value? maybe 0.02 uH or something like that.

Is the assumption, the bigger physical size of inductor the smaller it's inductance value?

 

[volker@muehlhaus]

I The smaller physical sized inductor has bigger value. I assume that's true.

No. Larger diameter means higher inductance, for same number of turns.
https://www.circuits.dk/calculator_planar_coil_inductor.htm

For inductors with ferrite core, there your be different magnetic materials used -> Al value
https://en.wikipedia.org/wiki/Magnetic_core#AL_value

 

[FvM]

Not a reasonable assumption. For power inductors with similar design, size will be in a first order related to energy storage capability 0.5 I² L. In your example, the 2 µH inductor is probably designed for a much larger rated current.

 

[schmitt trigger]

In addition to what FvM mentions (energy storage), inductors become physically much larger whenever they have to sustain DC bias. Dc bias saturates a core, therefore an air gap must be implemented. However, air gaps dramatically reduce Al, which reduce the available inductance per number of turns.

Lastly, not all magnetic materials are created equally, some may have fantastic core losses at the required operating frequency. Therefore different materials are used, and it so happens that better materials (usually, though there are exceptions) have a lower Al value.