A dual-mode switching voltage regulator has a duty cycle that varies with the input and output voltages so as to dynamically compensate for changes in the operating conditions. The switching voltage regulator uses input and output voltages/currents to optimize the duty cycle of the signals applied to a pair of switches disposed in the regulator. In the PFM mode, a control block senses the time that a first switch used to discharge an inductor is turned off. If the control block senses that the first switch is opened too early, the control block increases the on-time of a second switch used to charge the inductor. If the control block senses that the first switch is opened too late, the control block decreases the on-time of the second switch.