MOSFET gate drive sinking and sourcing urrent

Discussion in 'Analog & Mixed-Signal Design' started by Engineering_Junkie, Oct 4, 2016.

  1. Engineering_Junkie

    Thread Starter New Member

    Sep 9, 2015
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    Hey everyone,

    I just want to double check something. I have a resistor and diode in parallel to my MOSFET gate which the gate driver passes current through, it sources 1 amp through the resistor to the MOSFET to turn it on and bypasses the resistor through the diode to turn it off.

    My understanding is it will ever sink or source more current the its limit although when one of my friends ran a simulation he obtained a sinking current of 19 amp through he diode when the max sinking current of the driver is 4 amp.

    Just want to make sure I' not missing something and the simulation is in fact incorrect?

    Thanks in advance for any help.
    Image: http://imgur.com/a/21ajm
     
  2. Bordodynov

    Well-Known Member

    May 20, 2015
    1,043
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    Drajver=Vsource+2.5Ohm
    and 150Ohm -->15Ohm
     
  3. Engineering_Junkie

    Thread Starter New Member

    Sep 9, 2015
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    I'm sorry, but i dont quite understand?
     
  4. jpanhalt

    AAC Fanatic!

    Jan 18, 2008
    5,699
    912
    The gate is simply a capacitor. The current it gets is over quite a short period usually. Your gate resistance and current capability of the driver, which can be viewed as in internal series resistance, determine that time. Similarly, the turn off time/current is determined by the series resistance. It will not be higher than what your driver can sink.

    John
     
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  5. Bordodynov

    Well-Known Member

    May 20, 2015
    1,043
    317
    See
    Draft338.png
     
    Last edited: Oct 6, 2016
    Engineering_Junkie likes this.
  6. Engineering_Junkie

    Thread Starter New Member

    Sep 9, 2015
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  7. Engineering_Junkie

    Thread Starter New Member

    Sep 9, 2015
    28
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    thank you!
     
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