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Explanation of mosfet terms

Discussion in 'General Electronics Discussion' started by aidan, Apr 1, 2012.

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  1. aidan

    aidan

    29
    0
    Jul 15, 2011
    I wanna know what all these mean, things like:

    Gate to Source Voltage
    Single pulse avalanche energy rating
    Drain to gate Voltage

    And also the amplifying characteristics, like how much power i need to supply to the gate to get a certain amount of switched current

    Use this as an example:
    http://www.datasheetcatalog.org/datasheet/fairchild/IRF730.pdf
     
  2. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,496
    2,837
    Jan 21, 2010
    Gate to source voltage is simply the voltage as measured between the source terminal and the gate. This is typically abbreviated as Vgs.

    To know what it means, you need to look at what section of the datasheet you're in. For example, in the absolute maximum ratings section you'll have figures you should never exceed. In the electrical specifications you'll have threshhold voltages -- Vgs(th) -- which indicate the voltage between the source and the gate at which the device begins to conduct.

    Drain to gate voltage is something rarely seen because it is a breakdown limit that is typically captured by Vds and Vgs, although it is included in this datasheet Note that it tells you in this case that you can only have a max oVDS of 380V if you have -20V Vgs -- can you see how that is determined?

    Single pulse avalanche energy is the amount of energy the device can absorb from a single pulse if Vds is exceeded. If you do exceed Vds, then the device will conduct anyway, and the energy is determined by the voltage across the device, the current through it, and the duration of the pulse. Multiplying all of these out should not exceed this value.

    Avalanche operation is a fairly extreme condition and manufacturers have datasheets that explain it far better than I can. Here, and here are 2 examples.
     
  3. aidan

    aidan

    29
    0
    Jul 15, 2011
    thanks! my mind has been opened!
     
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