Devices and systems that use an adaptively limited PWM duty-cycle to control a circuit and methods and control programs to operate and to control the devices and systems to adaptively limit the PWM duty-cycle are disclosed. The devices and systems are capable of adjusting the duty-cycle such that the actual inductor current in the next cycle is precisely limited. Specifically, a maximum allowable duty-cycle for time interval N+1 is estimated during time interval N. When the duty-cycle is applied to the circuit at time interval N+1, the peak inductor current is kept below a maximum allowable inductor current level.