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What type of inductors are usually used on PCB for these applications?

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  • What type of inductors are usually used on PCB for these applications?

    All I know about inductors is that they have a quantity called inductance. This means that it resists change in current through it and it saves energy in its magnetic field. If one goes to buy an inductor, they come in a wide range of sizes and shapes. First there are the inductor types based on the core: Air Core Inductor, Iron Core Inductor, Ferrite Core Inductor, Laminated Steel, Core Inductor, Iron Powder Core Inductor, Ceramic Core Inductor​. Then there are different shapes of the core: torroidal inductor, multilayer inductor among others. It is all mind boggling and terrifying.

    The application we are thinking about for this question is: SMPS (all common types like buck, boost and buck-boost), filters using OpAmps i.e active filter design, passive filter design (e.g LPF, HPF, Pi-Filter). This question is not about high power applications or "niche" applications.

    There is no one more thing which is connected to this question so I am posting here. That is these terms: choke, ferrite bead and inductor. They all use a coil I believe so why use differnet words when they are all basically inductors?

    This question is asking one of the most mystifying things I have come across since I became an electronic engineer. The main reason so far I have not had to know the finer details of this topic is that I was writing code for digital designs.

  • #2
    The two reasons that I know for inductors is to either:
    - Store energy in an magnetic field
    - Suppress changes in current.
    Storing energy is what you want for SMPS while suppressing changes is for a filter.

    A choke "chokes" the changes and does not need to store energy. Ferrite beads do (often?) the same and are small.


    • #3
      if you need some background on inductors.. you can download the trilogy of magnetics from Wurth here

      Last edited by Paul van Avesaath; 09-12-2023, 02:49 PM.


      • #4
        Paul van Avesaath the very first mentioning of "choke" in the trilogy book mentions "storage choke". There goes my explanation...