Except when it's idiomatic. You can say it when you are about to leave but are not quite ready...no one is going to stand there expecting you to be out in 60 seconds. Okay, no one in Belgium, that is.
What about when you're out of breath and you say, "I need a minute." But you actually just need to rest for a moment or two because you're winded?
You will more likely say something like, "Wacht eventjes" or "Ik ben nog niet klaar".
No, as heb nodig is need. It also doesn't make sense grammatically in English.