Overview

Many battery-powered systems, such as smart phones, must be fully functional and their electronics up and running shortly after the user plugs a charger into the phone. The system electronics need to be functional regardless of the state of the battery, even if the battery is fully discharged or absent. The FAN5400 family charger IC allows power to be delivered to the system when the charger is plugged in, whether the battery is absent or present, and allows the system to power up and be functional quickly after the charger is plugged in. Other approaches, such as power path, add additional impedance in series with the battery.