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  1. #1
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    Using discrete logic to "make" a synchronous FET buck converter controller?

    Hello,

    Please can you state if the attached method for deriving discrete logic for Buck converter sync FET switching signals is optimal?
    We are designing a 300W Buck converter for down-hole application where ambient temperatures are 170degC.
    We cannot use a chip which does the sync FET driving signals as those chips can’t withstand 170degC.

    The delays and switching logic put in all seems very precarious and I worry about shoot through currents.
    Please can you state if you have a more reliable way to do it?

    (Ltspice sim and pdf schematic attached)

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  2. #2
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    Re: Using discrete logic to "make" a synchronous FET buck converter controller?

    Are you sure the chip can't work at 175C? Downhole
    applications seldom require the same service life as
    an industrial product's qualification assumes - like a
    few hundred hours max, at temp, vs a few thousand
    (at lesser temp).

    If you can find a ceramic package version of one you
    like, maybe do your own life testing and determine if
    you're just being sandbagged by the manufacturer?

    There are some rad hard bridge drivers that might be
    serviceable there, but you surely would not like the
    price. They are built on dielectric isolation material
    in foundry technology which I've played with its
    cousins, out to 300C.

    Have you looked to TI's "EP" lineup? They have some
    (not to say, exactly what you want) high temp power
    management and logic products.



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