Calculation of heatsink

Discussion in 'General Electronics Chat' started by pradeeba, Mar 5, 2008.

  1. pradeeba

    Thread Starter Active Member

    Feb 27, 2008
    104
    0
    can any one help me out in calculating heatsink area. am using offline SMPS switcher IC.calculated junction temperature seems to be higher than the value mentioned in the datasheet. so external heatsink is required.now how to choose the area of required heatsink?
     
  2. Lembit

    New Member

    Nov 13, 2007
    4
    0
    the simplest estimation is 10cm2 per avg W. It will do at room temperature, but a lot depends on your overall design of chassis etc.
     
  3. sudharshan

    Member

    Mar 3, 2008
    11
    0
    Avg watt means Watt. Give me an Example
     
  4. scubasteve_911

    Senior Member

    Dec 27, 2007
    1,202
    1
    He is saying that every 10 square centimeters, you can dissipate a watt. This is just a rule of thumb though, so if it is critical, then over-rate your heatsink according to the rule, or you will have to do some finite element modeling.

    A simple hand calculation doesn't lend itself to such a task. This is why heatsinks are spec'd given their thermal resistance in degrees/watt.

    Steve
     
  5. John Luciani

    Active Member

    Apr 3, 2007
    477
    0
    You need to look at the heatsink thermal resistance. Also can you use a fan in your
    application? How much can you afford to spend on a heatsink?

    You can purchase a heatsinks with a wide variety of fin arrangements. The
    purpose is to maximum the cooling surface area. Go to the heatsink manufacturers
    website and look at the thermal resistance specifications.

    Does the IC manufacturer have a heatsinking application note?

    (* jcl *)
     
  6. pradeeba

    Thread Starter Active Member

    Feb 27, 2008
    104
    0
    can anyone suggest me about heasink manufacturer website, so that i can get rich information about the heatsinks?
     
  7. scubasteve_911

    Senior Member

    Dec 27, 2007
    1,202
    1
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