Inductor selection

Discussion in 'General Electronics Chat' started by imraneesa, Mar 23, 2015.

  1. imraneesa

    Thread Starter Member

    Dec 18, 2014
    184
    4
    Dear Sirs.

    Attached is the image of buck drier, that drives laser diode with 2A current. I am designing the same type for which I am trying to find the inductor but unable to find.
    the inductor required is 22uf. and I know it is good to select current rating little higher than laser diode current i.e. 2A.
    Now in the image the inductor shown is 6.2mm diagonal and height is 2.4mm.
    Can anybody tell me where to find this inductor?
    when I tried in digikey when I select 22uf with current rating more than 2.6A I am not getting this size. I am getting big size inductors. Please tell me what is this confusion about and what I am missing. if in the driver he have selected current rating lower than the led current required?
     
  2. alfacliff

    Well-Known Member

    Dec 13, 2013
    2,449
    428
    the rthing that is confusing is that inductors are rated in Henrys, not Farads. 22uf is twenty two micro farad, a capacitor.
     
  3. imraneesa

    Thread Starter Member

    Dec 18, 2014
    184
    4
    oops sorry. I meant 22uH. sorry sorry.
     
  4. Roderick Young

    Member

    Feb 22, 2015
    408
    168
    Go to mouser.com, or digitkey, or one of the other major suppliers, and look for a 22 uH surface mount inductor. I took a quick look and there were over 1300 choices. Without knowing more about the design, it's hard to say what you need, exactly.
     
  5. #12

    Expert

    Nov 30, 2010
    16,298
    6,809
    You can't build a 2 amp inductor with 30 gauge wire. Whatever you arrive at, it will have significant mass.
     
  6. imraneesa

    Thread Starter Member

    Dec 18, 2014
    184
    4
    yes I want 22uH inductor and 2A current will be flowing into it. I want the size to be 6mmx6mm and height like 2.4~3mm.
     
  7. imraneesa

    Thread Starter Member

    Dec 18, 2014
    184
    4
    S0 can I choose less current rating even though 2A current passing through it.
    if I select 22uH of 1.6A instead 22uH of 2A current. what will happen?
     
  8. imraneesa

    Thread Starter Member

    Dec 18, 2014
    184
    4
    look at this datasheet. in page 4. they have mentioned 22uH inductor. what current rating I have to select for the inductor?
    that is for 1A output current. if I want to use the same circuit for 2A current. how much current rating inductor I have to select?
     
  9. takao21203

    Distinguished Member

    Apr 28, 2012
    3,577
    463
    you need higher rating since pulses will be higher.

    By the way these are quite common just dont take a too small kind- it will just get hot
     
  10. Roderick Young

    Member

    Feb 22, 2015
    408
    168
    If an inductor is used at above its rated current, most likely the inductance seen will be less than the marked rating. Between 1.6A and 2A, the circuit might still work fine. In fact, the original part might be rated for 1.6A. If this is your own design, I'd say try several different parts and see how they do.
     
  11. MikeML

    AAC Fanatic!

    Oct 2, 2009
    5,450
    1,066
    It is all about selecting an inductor that will never saturate due to the peak current through it. The peak current in the inductor is much higher than the average LED current.
     
  12. Lundwall_Paul

    Member

    Oct 18, 2011
    220
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