Datasheet Question

Discussion in 'General Electronics Chat' started by waldopulanco, Nov 27, 2013.

  1. waldopulanco

    Thread Starter New Member

    Nov 14, 2013
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    i was wondering on how to read a datasheet for transistor i mean i mean if i want to bias or operate the transistor how to prevent it from damaging,
    i have read the data sheet and i want to know some basic info example


    Code ( (Unknown Language)):
    1. collector-base voltage = 55V condition open emitter
    2.  
    3.  
    4.  Collector-emitter voltage = 55V condition RBE = 10 Ohms
    5.  
    6.  
    7.  Collector-emitter voltage = 30V condition Open Base
    8.  
    9.  
    10.  Emitter-base voltage = 3.5V condition open collector
    11.  
    12.  
    13.  Collector current(DC) = 0.4A
    14.  
    15.  
    16.  collector current peak value = 0.4A
    17.  
    18.  
    19.  total power dissipation = 3.5W condition up to Tmb = 25 °C
    20.  
    21.  
    22.  storage temperature = +200 °C
    23.  
    24.  
    25.  junction temperature = 200 °C
    26.  
    27.  
    28.  Power Output  = 1W

    Please can you explain it!! i want to know some basic information in datasheet!!


    Thanks in advanced!!
     
  2. KJ6EAD

    Senior Member

    Apr 30, 2011
    1,425
    363
    If you'd post a link to the actual datasheet you'd get more useful responses.
     
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  3. waldopulanco

    Thread Starter New Member

    Nov 14, 2013
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  4. crutschow

    Expert

    Mar 14, 2008
    13,009
    3,233
    I would think you understand some of those data sheet values. For example it would seem apparent that you shouldn't ever exceed the voltage, power or current ratings when using the device in a circuit. Which ones do you find particularly confusing?
     
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  5. waldopulanco

    Thread Starter New Member

    Nov 14, 2013
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    As an example the total power dissipation is 7 watts, what wattage can only apply during operation to avoid destroying the transistor? half of the total power dissipation or 3.5watts or 2watts?

    thanks!!
     
  6. MrChips

    Moderator

    Oct 2, 2009
    12,440
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    Where did you read 7W?
    You would want to use a heat sink on that transistor.
     
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  7. Alec_t

    AAC Fanatic!

    Sep 17, 2013
    5,797
    1,103
    You should always design a circuit such that the transistor operates well within its ratings. The bigger the margin you allow, the longer the life of the transistor is likely to be. With few exceptions I would aim to keep voltage/current/power at no more than 70% or so of the maximum.
     
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  8. crutschow

    Expert

    Mar 14, 2008
    13,009
    3,233
    For that amount of power you need a heat sink for the transistor as MrChips stated. You need to look at the thermal resistance of the transistor junction-to-case (θjc given in °C/W) and then determine the thermal resistance of the heat sink you need to dissipate the power at the highest ambient temperature the device will see while keeping the device junction temperature below its maximum rating by at least 25°C.
     
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