Apparatus and method for operating a device in a low power mode. In accordance with some embodiments, the apparatus comprises a memory and a system on chip (SOC) integrated circuit. The SOC has a first region with a processing core and a second region electrically isolated from the first region as an always on domain power island with a power control block. In response to a sleep command, the processing core transfers system data to the memory and the power control block enters a low power mode in which no electrical power is supplied to the first region. In response to a wake up command, power is restored to the first region and the processing core performs a reinitialization operation responsive to status information communicated by the power control block indicative of a state of the system during the low power mode.