| Abstract |
This paper presents an auxiliary-assisted 5:1 Series-Capacitor (SC) buck converter for fast transient response in 48V Point-of-Load (PoL) automotive applications. The 5:1 SC buck converter, which is implemented as the main hybrid stage, regulates the auxiliary buffer capacitor voltage, Vaux, and consequently, delivers the average load power. By regulating Vaux, the main hybrid stage facilitates the creation of an ancillary voltage bus for on-board electronics. The high-frequency auxiliary stage precisely regulates the output voltage, Vout with a Ripple-Based Constant On-Time (RB-COT) control scheme, by utilizing the energy stored in the buffer capacitor, Caux. With no stringent transient requirements on $V\_{AUX}$, the main stage is optimized to deliver the average load power, while the auxiliary stage is designed for high-frequency operation. A 50W, 48V-to-0.8V experimental prototype was built to validate the proposed architecture. Load transients from 5 A to 29 A were applied to the prototype, resulting in an output voltage deviation of 60 mV. The system achieves a peak efficiency of 89.5\% with an output capacitance of only 720 µF and an auxiliary capacitance of 120 µF. |
