1. A DC-DC conversion scheme comprising a main inductor connected in series with a first circuit leg and a second circuit leg, the first and second circuit legs being arranged in parallel with one another, wherein each circuit leg comprises a first inductor, a second inductor and a third inductor arranged in series with a primary switch, a first switched ground connection being connected to a location between the first and second inductors, and a second switched ground connection being connected to a location between the second and third inductors, the first, second and third inductors of the first and second legs being wound upon a common core.