Mosfet with a series diode.

Discussion in 'General Electronics Chat' started by Varkatzas, Nov 6, 2012.

  1. Varkatzas

    Thread Starter New Member

    Oct 22, 2012
    15
    0
    Hi,

    I've seen power MOSFET modules or MOSFETS configurations that include a series diode at the drain and it's opposite to the intrinsic internal diode. I know the applications of this modules are for zero current resonants, but i'm not sure what is the purpose of such diode.

    As i can see in the datasheets of these modules, due their high reverse recovery time and charge, the reverse current during this time can be high, which i guess it's undesirable; also, because of the voltage drop in direct polarization.

    Can someone explain the purpose of this diode and how it will work in a SMPS?

    Thanks.
     
  2. crutschow

    Expert

    Mar 14, 2008
    13,042
    3,244
    Not sure what you are referring to. Post a schematic.
     
  3. Varkatzas

    Thread Starter New Member

    Oct 22, 2012
    15
    0
    I attach the schematic of the MICROSEMI-APTM120UM70DAG which show the series diode.

    Thanks
     
  4. lokeycmos

    Active Member

    Apr 3, 2009
    432
    7
    i cant really tell you what its for, but if you dont need it just tap off the "DK" instead of the "D"
     
  5. toffee_pie

    Active Member

    Oct 31, 2009
    162
    7
    if you apply voltage source to the MOSFET, ie Vgs threshold, then you drive current from source to the drain.

    that diode prevents currents from going the other way (thus damaging the part), not 100% but my take up on it. Most fets that deal with high voltage levels would have them, and Insulated gate bipolars.
     
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