Info on a BS250 P Channel MosFET TO-92

Discussion in 'General Electronics Chat' started by spike1947, Mar 19, 2016.

  1. spike1947

    Thread Starter Member

    Feb 4, 2016
    39
    0
    Hi
    Could anyone tell me if a BS250 P-CHANNEL ENHANCEMENT MODE VERTICAL DMOS FET Transistor is normally open or closed , I have ordered some and I thought the Enhanced mode is normally closed , but not sure now and when I look at the data sheet I do not know were it says either way .
    I am wanting a normally closed mosfet ! , I think this is the type I ordered .

    http://www.diodes.com/_files/datasheets/BS250P.pdf


    cheers

    spike
     
  2. RichardO

    Well-Known Member

    May 4, 2013
    1,228
    382
    I am not sure what you mkean by "normally closed".

    This part is off when there is less 1 volt between the gate and source (negative on the gate). It starts to turn on when more than 3.5 volts is applied between the gate and source (negative on the gate).
     
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  3. dl324

    Distinguished Member

    Mar 30, 2015
    3,211
    619
    You want a depletion mode MOSFET or a JFET.

    The part you referenced is enhancement mode, as most discrete MOSFETs are.
     
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  4. ian field

    Distinguished Member

    Oct 27, 2012
    4,413
    782
    Enhancement mode need to be enhanced (by voltage applied to the gate) to make the channel conduct current.

    Depletion mode conduct as much as they're going to with no potential applied to the gate. Depletion MOSFETs are usually RF types - most depletion types are JFETS. The gate is just a PN junction, a reverse bias on that junction causes the depletion region to expand into the channel and strangle the current flow.
     
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  5. spike1947

    Thread Starter Member

    Feb 4, 2016
    39
    0
    Hi

    Sorry I meant "normally on " .

    spike
     
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