FAN3989 Overview
The FAN3989 is a USB-connection-monitoring device used to determine if a standard USB device is connected or a battery changing device is connected. The FAN3989 sets the FLAG1 pin to logic HIGH or LOW as an indicator to the system controller that a standard USB device or a charger is connected to the USB port. The FAN3989 also monitors the VBUS for over- or under-voltage conditions.