What MOSFET should I use

Discussion in 'The Projects Forum' started by newuser1029834535, Aug 30, 2016.

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  1. newuser1029834535

    Thread Starter New Member

    Jul 22, 2016
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    I am trying to choose a MOSFET for my project, but am not sure how to read the specifications.
    The specs I'm referring to are: Drain-Source breakdown voltage, Continuous Drain Current, and Power
    I need to pass 63v 24A through that MOSFET. What should I buy?

    Thanks for the advice.
     
  2. SLK001

    Well-Known Member

    Nov 29, 2011
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    Look for a 100V Vd-s MOSFET (or higher) with continuous current capabilities of 30A or greater. There's only a million different kinds of them.

    Are you high-side or low-side switching? Post your project schematics.
     
  3. crutschow

    Expert

    Mar 14, 2008
    12,988
    3,226
    The ON resistance is also important if you are using the MOSFET as a switch.
    If you want to avoid having to add a heatsink to the MOSFET then the ON resistance should be low enough so its I²R dissipation is less than about a watt (depending upon the MOSFET package) when conducting the 24A.
    This means the ON resistance should be less than 1.7mΩ.
     
  4. wayneh

    Expert

    Sep 9, 2010
    12,090
    3,027
    Agreed. I'll add that going to even higher amps often adds little cost. I mean, if 50A costs only a few cents more, if may be a better choice.

    The voltage you control the gate with is a factor. Anything less than 10V or so means you should look for a "logic level" MOSFET.
     
  5. SLK001

    Well-Known Member

    Nov 29, 2011
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    I'm waiting on the schematic, or usage information to be able to narrow it down further. There is a LOT of information that the TS left out to be able to help him out.
     
  6. newuser1029834535

    Thread Starter New Member

    Jul 22, 2016
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    these are the schematics I am using, they are not mine though, I found them on the internet and I am adapting them to my needs. I need to change the IRF3205 for something that can handle more power.
    Currently I am undecided between IRF3205PBF-ND and IXFX420N10T-ND. The first one is much less expensive but the power dissipation is only 200W.. The second is much more expensive but the power rating is ok (1670W). The resistence is a little bit high on both the MOSFETS but they will be on for a very short amount of time so that shouldn't be a problem. I'm will use 5V to activate the MOSFET.

    What should I choose?
     
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  7. SLK001

    Well-Known Member

    Nov 29, 2011
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    You need to tell us what your circuit is doing. What makes you think that the coil will require up to 25A? What kind of coil is it? Your circuit is NOT what you want to use, unless your goal is to burn out the FET.
     
  8. newuser1029834535

    Thread Starter New Member

    Jul 22, 2016
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    It's a 1 stage coil gun and I am using some 63v caps I have laying around. An online calculator estimated that they will output 25A all combined.
     
  9. ScottWang

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    Aug 23, 2012
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