MOSFET - Practical design examples

Discussion in 'General Electronics Chat' started by DumbDummy77, Feb 22, 2010.

  1. DumbDummy77

    Thread Starter Member

    Jan 21, 2010
    43
    0
    Hello

    I am in the process of selecting right MOSFET for my application which involves a hard switching at high frequency and under 50A. According to my mosfet datasheet, high input capacitance is 7nF, and Cre - 300pF which potentially problem. I have been told by someone and I did not have the chance to ask why. What is the drawback of these parameters?


    Secondly, I do not have any textbook that covers any hard-switching, power loss, switching loss, etc. I need these information in order to complete my design in the correct manner. Do you know any document or book will help to cover the design with maybe example and tutorials?

    DumbDummy77
     
  2. MikeML

    AAC Fanatic!

    Oct 2, 2009
    5,450
    1,066
    Look at what simulation can teach you. Here is a stupidly simple circuit. If you examine the V(G) trace, you can see the effect of gate charge, Miller capacitance, and the resulting time constant caused by the 100Ω gate resistor.

    Look at V(D) and you can see the effect of Ron, and the delay in rise of drain current and due to the gate capacitance. Look at the Light Blue trace and you can see the power dissipation that occurs in the FET because it is switching rather slowly...
     
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