A method of operating an accessory (200, 400), the method comprising: establishing a connection to a portable computing device (100, 402); receiving operating power from the portable computing device (100,402) via the connection; communicating a command to the portable computing device (100, 402), the command requesting that the accessory (200, 404) continues to receive power from the portable computing device (100, 402) when the portable computing device (100, 402) is in a hibernation mode, wherein the command specifies a level of power that should be provided to the accessory (200, 404) during the hibernation mode, wherein the specified level of power is lower than a normal operating power and high enough to enable the accessory to detect an accessory event; and subsequently to communicating the command, while the portable computing device (100, 402) is in the hibernation mode: receiving power at the specified level from the portable computing device (100, 402) via the connection, wherein the portable computing device (100, 402) provides the power at the specified level while in the hibernation mode based on the command; using the power received from the portable computing device (100, 402) to detect an accessory event; and in response to the accessory event, sending a wake event signal to the portable computing device (100, 402), wherein the wake event signal signals the portable computing device (100, 402) to wake from the hibernation mode. establishing a connection to a portable computing device (100, 402); receiving operating power from the portable computing device (100,402) via the connection; communicating a command to the portable computing device (100, 402), the command requesting that the accessory (200, 404) continues to receive power from the portable computing device (100, 402) when the portable computing device (100, 402) is in a hibernation mode, wherein the command specifies a level of power that should be provided to the accessory (200, 404) during the hibernation mode, wherein the specified level of power is lower than a normal operating power and high enough to enable the accessory to detect an accessory event; and subsequently to communicating the command, while the portable computing device (100, 402) is in the hibernation mode: receiving power at the specified level from the portable computing device (100, 402) via the connection, wherein the portable computing device (100, 402) provides the power at the specified level while in the hibernation mode based on the command; using the power received from the portable computing device (100, 402) to detect an accessory event; and in response to the accessory event, sending a wake event signal to the portable computing device (100, 402), wherein the wake event signal signals the portable computing device (100, 402) to wake from the hibernation mode. receiving power at the specified level from the portable computing device (100, 402) via the connection, wherein the portable computing device (100, 402) provides the power at the specified level while in the hibernation mode based on the command; using the power received from the portable computing device (100, 402) to detect an accessory event; and in response to the accessory event, sending a wake event signal to the portable computing device (100, 402), wherein the wake event signal signals the portable computing device (100, 402) to wake from the hibernation mode.