+ Post New Thread
Results 1 to 6 of 6
  1. #1
    Advanced Member level 5
    Points: 31,570, Level: 43
    Achievements:
    7 years registered

    Join Date
    Sep 2008
    Location
    cambridge
    Posts
    6,598
    Helped
    478 / 478
    Points
    31,570
    Level
    43

    High power, short time power pulses in FETs

    Hi,
    Do you think that this FET (STD3NK90Z) could conduct 0.7A (with a Vds of 440V) for 50us?
    Then also for 500us?
    STD3NK90Z FET:
    https://www.st.com/resource/en/datasheet/stp3nk90z.pdf

    •   AltAdvertisment

        
       

  2. #2
    Advanced Member level 2
    Points: 4,707, Level: 16

    Join Date
    Feb 2014
    Posts
    634
    Helped
    220 / 220
    Points
    4,707
    Level
    16

    Re: High power, short time power pulses in FETs

    Treez I see the answer in figure 1, Safe operating area for DPAK, TO-220.

    I see it able to conduct more than 10A for 1mS with 500Vds.


    1 members found this post helpful.

    •   AltAdvertisment

        
       

  3. #3
    Advanced Member level 5
    Points: 31,570, Level: 43
    Achievements:
    7 years registered

    Join Date
    Sep 2008
    Location
    cambridge
    Posts
    6,598
    Helped
    478 / 478
    Points
    31,570
    Level
    43

    Re: High power, short time power pulses in FETs

    Thanks, this fet can dissipate 1600w for 100us and no more....imagine it dissipating 1600W for 200us, then nothing for 0.999800 seconds...repeatedly.....thats only 0.32W on average, but this TO220 FET wouldnt be able to do that...seems incredible.
    I cant see how it can heat up seriously in 100us....even with 1600W



    •   AltAdvertisment

        
       

  4. #4
    Advanced Member level 5
    Points: 22,863, Level: 36
    barry's Avatar
    Join Date
    Mar 2005
    Location
    California, USA
    Posts
    4,368
    Helped
    970 / 970
    Points
    22,863
    Level
    36

    Re: High power, short time power pulses in FETs

    Quote Originally Posted by treez View Post
    Thanks, this fet can dissipate 1600w for 100us and no more....imagine it dissipating 1600W for 200us, then nothing for 0.999800 seconds...repeatedly.....thats only 0.32W on average, but this TO220 FET wouldnt be able to do that...seems incredible.
    I cant see how it can heat up seriously in 100us....even with 1600W
    That's a naive view. There will be local hotspots in the device that can cause damage. Do you think you can withstand 100000 volts across your body with a 1:100000 duty cycle? It's only an "average" of 1 volt...


    1 members found this post helpful.

  5. #5
    Advanced Member level 5
    Points: 15,875, Level: 30

    Join Date
    Nov 2012
    Posts
    2,911
    Helped
    701 / 701
    Points
    15,875
    Level
    30

    Re: High power, short time power pulses in FETs

    this fet can dissipate 1600w for 100us and no more....imagine it dissipating 1600W for 200us, then nothing for 0.999800 seconds...repeatedly.....thats only 0.32W on average
    It depends on the anatomy: the inner constructions.

    1600W for 100us results in 0.16J of energy. How efficiently this is spread over inside the the die?

    During the rest period, the heat will spread- it moves by diffusion. The die will cool down but not to the ambient temp.

    When the next pulse comes with another 0.16J of heat, the temp will rise further (because the die is already pre-heated). I do not know the exact details, but the steady state dissipation will be the one when the input heat is balanced by the heat lost by the package.

    The graphs are there for guide only; you need to be careful while working close to the borderline.

    - - - Updated - - -

    I see it able to conduct more than 10A for 1mS with 500Vds.
    Did you mean 1.0A?


    2 members found this post helpful.

    •   AltAdvertisment

        
       

  6. #6
    Advanced Member level 2
    Points: 4,707, Level: 16

    Join Date
    Feb 2014
    Posts
    634
    Helped
    220 / 220
    Points
    4,707
    Level
    16

    Re: High power, short time power pulses in FETs

    Quote Originally Posted by c_mitra View Post


    Did you mean 1.0A?
    Yes you're right, I misread.


    1 members found this post helpful.

--[[ ]]--