Current-controlled switching regulator using a DC-DC converter with high-step-down voltage gain

During the last two decades, a great number of applications for DC-DC converters have been reported. New technologies are requiring low voltages. A possible solution to this problem is to use a transformerless high-step-down voltage converter where the conversion ratio depends on an integer number that indicates the number of times the steady-state duty ratio is multiplied by itself to obtain a high-voltage reduction. A controller design methodology is given in this study for such converter using average current-mode control. The proposed controller scheme employs the inductor current of the input stage and the capacitor voltage of the output stage. The advantage of using the selected current is that changes in the input source will have an immediate effect in the controller. The sensed current can also be used for one cycle overload protection; therefore the full benefits of current-mode control are maintained. The resulting switching regulator is able to provide a high-step-down voltage reduction and a regulated output voltage. Experimental results are given for a switching regulator with a voltage reduction from 48 to 1.5-V where the robustness of the proposed controller is tested under changes on the output load.