Patent ID: 6995963

Claim:
A power manager unit for managing power delivered to a battery powered device, comprising: a voltage converter unit arranged to convert an external voltage received by an external voltage supply by way of a cable to a supply voltage, wherein the cable includes a number of lines some of which are data lines arranged to form a transmit-receive connection and at least one of which is a power line arranged to carry the external voltage from the external voltage supply to the battery powered device; a voltage sensor unit coupled to the voltage converter unit for sensing a voltage; a comparator unit coupled to the voltage sensor unit arranged to generate a switching signal based upon the sensed voltage; and a switchover circuit coupled to the comparator unit arranged to receive the switching signal, wherein the switchover circuit responds to the received switching signal by connecting the battery powered device and a not fully charged battery to the voltage converter unit such that the supply voltage is provided thereto, wherein when the battery is substantially fully charged, the switchover circuit responds by electrically disconnecting the battery so as to not overcharge the battery.