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Pulling current through a FET while it's turning off

Discussion in 'Electronic Design' started by panfilero, Jun 19, 2013.

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  1. panfilero

    panfilero Guest

    Hello,

    I'm trying to figure out how much current I can pull through a FET while its turning off... basically, how fast I have to turn it off if I have it hooked up to a constant current load so that the load doesn't kill my part while it goes through its resistance region... what information on the datasheet should I be looking at to figure this out?

    I'm guessing it's the power dissipation rating, but I'm not sure....


    Here's the FET I'm using

    http://www.st.com/web/en/resource/technical/document/datasheet/DM00048681.pdf

    much thanks!
     
  2. Joerg

    Joerg Guest

    You'll have to keep your eye on figure 2, the safe operating area or
    SOA. Make sure you never exceed the limits. For example, while at 200V
    Vds it can take 20A for 1mseec, but if it takes 10msec then only 7A.


    De nada :)
     
  3. Joerg

    Joerg Guest


    Oh, and that's for single pulse or "once in a blue moon". If such
    situations happen in rapid succession you need to also get into figure 3
    and avoid death local excessive local heating.
     
  4. Jamie

    Jamie Guest

    That's a nice part.

    to bad the gate cap is so high but I guess it would depend
    on the application at hand.

    It really depends on your application, I can see that being used in
    auto applications incase of load dumps etc.

    Personally my self, I wouldn't want a supper fast switching speed, with
    high voltage on drain side, the miller effects could prove to be
    interesting.

    Jamie
     
  5. Guest

    Guest Guest

    Hello,

    I'm trying to figure out how much current I can pull through a FET while its
    turning off... basically, how fast I have to turn it off if I have it hooked
    up to a constant current load so that the load doesn't kill my part while it
    goes through its resistance region... what information on the datasheet
    should I be looking at to figure this out?

    I'm guessing it's the power dissipation rating, but I'm not sure....


    Here's the FET I'm using

    http://www.st.com/web/en/resource/technical/document/datasheet/DM00048681.pdf

    much thanks!

     
  6. josephkk

    josephkk Guest

    That is just not enough information. Where might the current
    alternatively go to and what is the compliance of the current source? Is
    there any energy transfer capacitors or inductors involved?

    ?-)
     
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