According to an embodiment of the invention, an apparatus is provided which includes a microprocessor, and a built-in temperature sensor configured to measure a temperature of the microprocessor as a reference temperature. The apparatus further includes external temperature sensors, where at least one of the external temperature sensors is configured to measure the temperature of the microprocessor. The microprocessor is configured to make an external temperature calibration using the reference temperature measured by the built-in temperature monitor. Each of the external temperature sensors is configured to monitor temperature information of a component and provide the temperature information to the microprocessor.