an electronic device , comprising a plurality of data storage cells , collectively operable in a data access mode and separately in a sleep mode . the sleep mode comprises a period of time during which the plurality of data cells are not accessed and during which a data state stored in each cell in the plurality of data cells is to be maintained at a valid state . the electronic device further comprises circuitry for providing at least one temperature - dependent voltage to at least one storage device in each cell in the plurality of data storage cells during the sleep mode .