Reduce cutrrent of SMPS

Discussion in 'Power Electronics' started by Avijit Palit, Aug 2, 2017.

  1. Avijit Palit

    Thread Starter Member

    Jul 19, 2017
    81
    1
    I have a smps, output voltage about 12v and current about 18a.
    How to reduce current from 18A to 2A.
     
  2. tcmtech

    Distinguished Member

    Nov 4, 2013
    2,809
    2,703
    Use a smaller load that only draws 2 amps.
     
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  3. Avijit Palit

    Thread Starter Member

    Jul 19, 2017
    81
    1
    But if I add a registor, accordingly is it reduces voltage?
     
  4. ScottWang

    Moderator

    Aug 23, 2012
    6,257
    970
    Do you mean that you want to add a regulator?

    When you add a regulator then the output voltage could be reduces about 2~3V.
     
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  5. Avijit Palit

    Thread Starter Member

    Jul 19, 2017
    81
    1
    But I want to reduce only current.
    Voltage must remain unchanged.
     
  6. Bordodynov

    Well-Known Member

    May 20, 2015
    1,821
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    Do you want to limit the maximum load current ?. Do you want to remake the circuit? Or do not you want to redo the scheme and everything will be done magically? Theoretically, this is possible (reworking the scheme).
     
  7. Dodgydave

    AAC Fanatic!

    Jun 22, 2012
    7,418
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    What load are you running on the psu, can you show pictures of the circuit or a diagram?
     
  8. dendad

    Well-Known Member

    Feb 20, 2016
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    Your power supply will only supply the current the load needs. UP TO a max of 8Amps. If you load only draws 2 Amps, that is all it will supply. You don't keep the voltage the same and reduce the current to the load by changing the power supply. You have to change the load.
    There is nothing at all wrong with running a 2A load on an 8A supply, as long as the volts are ok.
    In fact it is better to have a larger current capacity supply than to run the supply at its max current.
     
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  9. Avijit Palit

    Thread Starter Member

    Jul 19, 2017
    81
    1
    If I make current divider circuit then?
     
  10. crutschow

    Expert

    Mar 14, 2008
    19,552
    5,451
    Most loads take only the current they need.
    Can you explain why you think you need to reduce the current? :confused:
     
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  11. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
    5,360
    1,183
    Avijit,
    The basic concept that you do not seem to know is that typically the load/device attached to the power supply will only "draw (or pull)" the current it needs from the power supply..
    The power supply does not "push" 18 Amps into your load..
    18 Amps is just the maximum current that can be safely "drawn/pulled" from the power supply

    Just like a car can go 150+ km/hour but your foot controls how fast it really goes..
    It has the potential for 18 Amps but the load will draw only what it needs..
    You do not need to do anything.

    Your device says "hey power supply.. I'm going to take 2 Amps" and the power supply says "ok" the power supply does not say "screw you device.. you asked for 2 Amps and I don't care what you want so here is 18 Amps"...

    Now there are certain specific instances where that basic information is not true.. (a discrete LED might be one of those specific situations.. an LED needs to be fed the proper amount of current)

    So to continue this conversation please tell us exactly what you want to hook up to this power supply so we can tell you if you need to do anything special or if you just hook up your device to the power supply directly..

    Is this an LED? If so please provide us with the part number or link to the datasheet..
     
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  12. gerty

    AAC Fanatic!

    Aug 30, 2007
    1,230
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    What is it you are trying to do? What are you trying to limit the current to? It is easier for us to help you when we know what your goal is.
     
  13. bertus

    Administrator

    Apr 5, 2008
    18,371
    3,521
    Hello,

    @gerty , As I recall he is looking to power a motor of wich he does not know the power ratings.
    In this thread he gives the same specs for the powersupply:
    Measurement of wattage of motor

    Bertus
     
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