In　this　article,　high　step-down　dc-dc　converters　are　widely　employed　in　data　center　applications.　Due　to　the　higher　step-down　conversion　ratio　in　the　new　generation　48　V　voltage　regulator　module,　a　conventional　buck　converter　is　not　suitable　for　such　applications.　To　conquer　this　problem,　a　novel　dc-dc　converter　is　proposed　in　this　article　to　achieve　an　ultrahigh　step-down　voltage　conversion　ratio　for　data　centers.　The　nonisolated　topology　can　be　optimally　designed　to　integrate　both　the　switched-capacitor　and　coupled　inductor　techniques,　which　allows　zero-voltage-switching　(ZVS)　of　all　active　switches　to　be　achieved　and　improves　high　efficiency.　In　addition,　the　converter　presents　the　advantages　of　lower　voltage　stress,　ultrahigh　voltage　gain,　common　ground,　and　simple　control　strategy.　A　comprehensive　analysis　of　the　steady-state　analysis,　derivation　of　voltage　gain,　voltage　stress,　and　ZVS　condition　is　presented　in　detail.　Finally,　a　30　W,　48-to-1　V　experimental　prototype　is　built　and　tested,　which　validates　the　ultrahigh　step-down　voltage　gain　and　soft-switching　characteristic　of　the　proposed　converter.　The　maximum　efficiency　of　the　prototype　is　89.1%　and　the　efficiency　is　81.4%　in　full-load　condition.