The USB type-C port becomes more popular in the past few years, which consolidates various data communication and the power transfer. The USB power delivery even extends the power capability up to 100W. The typical 5V, 9V, 15V and 20V input voltages charge 1s~4s battery, therefore the buck-boost topology is required. This on-demand training introduces several advanced applications of buck-boost charger on the type-C power delivery products, such as power bank, car charger, type-C port on notebook, desktop, monitor. It also explains how unique features of buck-boost charger facilitate users to meet USB PD 3.0 specification.  The application diagram illustrates how the system is designed to comply the USB PD 3.0 specification.