This course focuses on the Totem Pole Bridge-less Power Factor Calibrator (TP-PFC) and why Gallium Nitride (GaN) is the best power switch for it. The session starts with AC/DC power basics, and explain the structure and basic operation of the TP-PFC, including a comparison with the classic PFC solution and why GaN is better, and then explain the advantages, equipment characteristics, and robustness of TI GaN in TP-PFC. Finally, we will guide you how to select the right TI GaN product, what are the on-resistance for typical power levels and design tools, and what are the general TI reference design combinations for TP-PFC.