#Hybrid DCDC converter (PS3B) vs Switch-capacitor converter

Disadvantage of SC：

• ultra-high density capacitors
• operate over a small number of conversion ratios
• need small inductors tend to have high DC resistance

Advantages of hybrid DCDC

• regulate to arbitrary output voltages
• large conversion ratio
• input current is continuous

Topology

在$S_1,S_2$都断开的时候，稳定态下，$V_{C_F}=V_{IN}$

当$S_1$闭合，$S_2$断开，瞬态下，$V_{X_1}$变为$V_{OUT}$，电容想要保持$V_{C_F}=V_{IN}$，$V_{X_2}=V_{OUT}-V_{C_F}=V_{OUT}-V_{IN}$。所以电流分别从$L_1,L_2$流到Output。

当$S_2$闭合，$S_1$断开，瞬态下，$V_{X_2}$变为$V_{OUT}$，电容想要保持$V_{C_F}=V_{IN}$，$V_{X_1}=V_{OUT}+V_{C_F}=V_{OUT}+V_{IN}$。

根据电感的volt-second平衡，$C_F$ is balanced at $V_{IN}$.