continually operate or become overloaded and accordingly generate a large amount of heat in that case the controller 100 may reduce the system clock for example the controller 100 may use up to the maximum system clock rate e g 1 4 ghz in a normal mode however it may only use up to a preset clock rate e g 500 mhz in a heat generation suppressing mode the temperature on an outer surface of the mobile device may differ from the internal temperature of the mobile device detected by the temperature sensor 130 the temperature on the outer surface of the mobile device that the mobile device user can feel and the internal temperature of the mobile device as detected by the temperature sensor 130 may be empirically measured thereby setting a temperature to determine that a state in which an unacceptable heat is generated inside the mobile device if for example the temperature sensor 130 is installed near the controller 100 the outer surface temperature and the detected temperature may be acquired as described in the following table 1 the outer surface temperature refers to a temperature on the outer surface of the mobile device the detected temperature refers to an internal temperature of the mobile device that is detected by the temperature sensor 130 and corresponds to.