A battery-powered, highly efficient, single-ended forward converter with new driving method for synchronous rectifier

A compact and highly efficient nonisolated step-up/step-down converter is described for battery input and low-output voltage applications. The circuit has a single-ended forward converter with synchronous rectifiers that are driven using a new driving method. The new method uses the drain voltage of the main switch to drive the freewheeling MOSFET. Experimental results are presented for a converter with an input voltage range of 0.9 to 1.65 V, an output voltage of 1.6 V and a load current of up to 200 mA. A maximum overall efficiency of 78% was obtained experimentally by using the new driving method in a freewheeling synchronous rectifier.