Patent ID: 6920575

Claim:
A power source switching unit with an integrated charging circuit for selectively coupling an external power source, a computer loads and one or more batteries, for providing temporary power during coupling, and for charging the one or more batteries, comprising: an external power receiving unit to transfer-electric power from an external power source to a power output to which a computer load is coupled; a detector, directly coupled to the power output of the external power receiving unit, to measure the voltage supplied by the external power receiving unit and detect a loss of the electric power supplied from the external power source to the external power receiving unit, wherein said detector detects the loss of the electric power supplied from the external power source to the external power receiving unit by measuring the voltage level supplied by the power output and comparing the voltage level to a fixed reference voltage, regardless of whether power is being supplied by the one or more batteries; one or more battery power supply circuits to selectively couple one or more batteries to the computer loads and the one more batteries to an integrated charging device; the integrated charging device, coupled to the power output and to the one or more battery supply circuits, wherein the charging device is capable of selectively trickle charging and rapid charging the one or more batteries with the electric power supplied from the power output; a control unit to selectively cause the one or more battery supply circuits to couple the one or more batteries to the integrated charging unit during periods when the external power receiving unit is receiving electric power and to cause the one or more battery supply circuits to couple the one or more batteries to the computer load within a predetermined time in response to detector detecting a loss of the electric power supplied from the external power circuit; and a rechargeable temporary power supply device to supply electric power to the computer load for at least the predetermined time in response to the detector detecting the loss of the electric power supplied from the external power circuit.