I suspect that the OP wants to do a buck with a hi-side fet and yet doesn’t want the hassle of hi-side current sense……..but I would say, possibly use a current sense transformer to do your current sense.
Ive actually seen solar bucks with no current sense…….they charge batteries….and as long as the battery voltage is high enough, you can actually do it without current sense, as long as you obviously limit the duty cycle…….the problem happens.. if the output suddenly goes short circuit and then of course your buck inductor current staircases up into saturation and bang goes the fet……unless of course, your microcontroller was able to sense the output short circuit quick enough and turn off the fet pronto.
But yes, if using the ucc384x then you would have to drive its oscillator with a micro because otherwise it needs the current sense ramp to know when to turn off the fet.
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here is a nice uc384x buck, to show how it works..in ltspice