say you set D high for max load, then suddenly someone suddenly disconnects the load.....how do you ensure your output voltage doesn't sky high......I suppose you need output overvoltage trip, but better still , you need a negative feedback loop to control the D...if you do that in software then that is very difficult...a co called converter technology in reading are tryin gto make a range of controllers that close the loop in software, and all us the user does is literally key in what we want vout to be, fsw, feedback loop bandwidth etc.