A Novel Hybrid Buck-Boost Converter Topology for Li-ion Batteries with Increased Efficiency

A novel two-phase hybrid Step-Up/Down converter for Lithium battery-powered systems is presented. The inductor is connected to the input and is followed by a charge-pump configuration using two external flying capacitors. With these, we facilitate smaller voltage rated switches, parallel conduction path, partial soft-charging of the flying capacitors, and continuous input and output current delivery. The overall converter loss and reliability concerns arising from discontinuous input/output current transfer are thus greatly reduced, even for heavy load conditions. The proposed topology promises a compact silicon and PCB footprint while providing comparable or better efficiency than state-of-the-art hybrid converter solutions. Simulation results show that 95.7% of peak efficiency can be achieved even for a 288 mΩ inductor DCR with a small output ripple of up to 18 mV.