In accordance with the teachings described herein, a method and apparatus
for handling a charging state in a mobile electronic device is provided.
A universal serial bus (USB) interface may be used for connecting the
mobile device to a USB host. A processing device may be used to execute
programs and to control operation of the mobile device. The processing
device may be operable to receive an enumeration acknowledgement signal
from the USB host via the USB interface and generate an enable signal
upon receiving the enumeration acknowledgement signal. A rechargeable
battery may be used to power the processing device. A battery charger may
be used to receive a USB bus voltage from the USB interface and use the
USB bus voltage to power the processing device and to charge the
rechargeable battery. The battery charger may be further operable to
receive a charge enable signal that enables and disables the battery
charger from powering the processing device and charging the rechargeable
battery. A timing circuit may be used to detect the USB bus voltage and
to measure the passage of a pre-determined amount of time upon detecting
the USB bus voltage. A battery charger enabling circuit may be used to
generate the charge enable signal to control the battery charger, the
battery charger enabling the battery charger if the timer has measured
the passage of the pre-determined amount of time or the enable signal is
received from the processing device.