Patent ID: 8719629

Claim:
A power-backup device comprising: a power input for receiving primary power; a power output for providing output power; a primary switch having a primary switch input connected to the power input, a primary switch output connected to the power output, and a primary switch control configured and arranged to enable a current path between the primary switch input and the primary switch output, thereby providing power to the power output; a secondary switch having a secondary switch output connected to the power output, a secondary switch input, and a secondary switch control configured and arranged to enable a current path between the secondary switch input and the secondary switch output in response to detecting a problem with the primary power, thereby providing power to the power output; a power storage circuit connected to the secondary switch input and configured and arranged to provide stored power to the secondary switch; and a control circuit configured and arranged to provide a control signal to the secondary switch control, the control signal generating an increasing voltage level that delays full-enablement of the secondary switch by increasing the voltage level over a period of time, the period of time being responsive to inrush current caused by enabling the secondary switch.