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  1. #1
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    satya_vijayawada's Avatar
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    pfc mosfet failure

    Hai

    iam facing a problem with boot converter(PFC).

    iam using MC33260D power factor ic, at 100W(Vout=400V and PFC transformer core is PQ26/20)condition the mosfet was damage

    due to the over heating.

    Space not available for, to increase the heat sink size.

    how to reduce the heat and mosfet failure

    and also observe the small audio noise in power supply

    Pls give me the reply

    with regards

    satya

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  2. #2
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    pfc mosfet fail

    First of all you need to understand if the power dissipation is within the design limits. If it is, then you will look at ways to decrease it (although you should have allowed for an adequate heatsink in the first place, if you knew the power dissipation).

    If it isn't, then you need to understand what makes the MOSFET dissipate more:
    - is the MOSFET driven fully on?
    - is the switching frequency correct?
    - is the inductor sized correctly? does it by any chance saturate?
    - is the Rdson of the MOSFET low enough?
    - is the diode adequate for PFC use?
    - did the MOSFET fail because of power dissipation, really? are the Vds voltage and Id within limits? do you have adequate margin, especially for Vds?


    If everything seems OK, then look for ways to decrease the power dissipated in the MOSFET:
    - use a MOSFET with lower Rdson (or two MOSFETs in parallel).
    - use lower switching frequency if possible
    - use a gate driver to speed up the MOSFET

    Failing all that, consider forced-air cooling.

    Hope this helps.



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  3. #3
    Newbie level 5
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    mosfet for boost converter

    Did you control duty cycle?



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