A method of performing a dynamic voltage and frequency scaling operation comprises controlling a clock management unit (CMU) to predict an operating state of a central processing unit (CPU) and to provide operating frequency information to a power management integrated circuit (PMIC) based on the predicted operating state of the CPU, the operating frequency information indicating a change of an operating frequency of an application processor, and controlling the PMIC to change an operating voltage of the application processor based on the operating frequency information provided from the clock management unit.