Switching chargers have widely been used in various products, such as smart phones, tablet computers, etc., due to the ability of quickly charging lithium batteries. However, the charging time is of increasing concern as the capacity of a lithium battery increases. Typically, a switching charger can reduce the charging time by increasing a charging current. However, in some cases, the charging power may be limited by an input power supply, such that switching charger utilizes the input power supply to the maximum extent. This can reduce the charging time, as well as protect the input power supply from being damaged because of overload.