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    protecting mosfets from high voltage

    Both ESD and TVS parts have much higher clamping voltage than their breakdown voltage.

    If a diode is to breakdown at 15v and its rated clamp voltage is ~8v above max Vgs of a MOSFETs gate is this not likely to protect the MOSFET?

    Are there other devices intended for this specific role?

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    Re: protecting mosfets from high voltage

    The question is too general for a meaningful answer. When selecting protection devices, you need to consider the characteristic of the driving source. E.g. TVS diode clamping voltage is specified at several 10 A surge current. Do you expect gate driver currents of this magnitude?


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    Re: protecting mosfets from high voltage

    Quote Originally Posted by FvM View Post
    The question is too general for a meaningful answer. When selecting protection devices, you need to consider the characteristic of the driving source. E.g. TVS diode clamping voltage is specified at several 10 A surge current. Do you expect gate driver currents of this magnitude?
    The real inquiry is just how much volts above max Vgs does it take to damage a MOSFET gate pulsed.
    Last edited by Zak28; 18th December 2018 at 12:31.



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    Re: protecting mosfets from high voltage

    Hi,

    I assume you donīt connect too high DC voltage source to a gate.

    DC voltage causes power ... dissipated as heat. Both ESD protection devices as well as TVS ar not designed to dissipate high - continous - power.

    Whatīs the idea behind your question.
    A sketch with a bit of description could clarify the doubts...

    Klaus
    Please donīt contact me via PM, because there is no time to respond to them. No friend requests. Thank you.



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    Re: protecting mosfets from high voltage

    Start with how and where, referred to what, the "high voltage"
    will be imposed. Some classes of fault become unlikely when
    things are assembled (like, the driver may be what protects
    the gate from gate-node "stimulus" by its own ESD network).

    You can't prevent every scenario but some prevent themselves
    in the end.

    Avalanche rated FETs will take some abuse on the drain (as long
    as the source is tied down well w.r.t. the threat source - the
    return path matters as much as the "injection point").

    There exist some FETs with built in gate protection zeners.



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