Abstract: An uninterruptible power supply unit for coupling between an adapter with an adapter connector and an electronic device in accordance with one embodiment of the present invention includes a self-contained housing, a backup power supply, and an output switch system. The self-contained housing has an input port for coupling with the adapter connector from the adapter and an output connector extending from the housing for coupling with the electronic device. The backup power supply is located in the housing and provides the backup power. The output switch system is also located in the housing. The output switch system is coupled between the output connector and the input port and the backup power supply and couples the backup power from the backup power supply to the electronic device when incoming power from the adapter fails.