Maximun duty cycle and burst current

rama1001

i have been trying to write a logic in C to produce a burst current as output but i don't find any way to make it possible. My concern is to produe a burst current even at maxim duty cycle. My duty cycle is always at maximum but the current should depend on the user setting. I am not quiet understand how can i do it at maximum duty cycle.

Can any one have suggestions for me?