METHOD OF OPERATING SEMICONDUCTOR DEVICE

System on chip including plurality of processors including first and second processors; plurality of intellectual properties (IPs) including first and second IPs; memory interface; internal clock circuit to receive reference clock signal, generate first internal clock signal, and provide first internal clock signal to first IP; memory interface clock circuit to receive reference clock signal, generate memory interface clock signal, and provide memory interface clock signal to memory interface; and power management unit (PMU), wherein first internal clock signal drives first IP, memory interface clock signal drives memory interface, PMU generates first control signal based on operational states of plurality of processors, and provides first control signal to internal clock circuit, PMU generates second control signal based on operational states of plurality of processors, and provides second control signal to memory interface clock circuit, internal clock circuit sets clock rate of first internal clock signal based on first control signal, and memory interface clock circuit sets clock rate of memory interface clock signal based on second control signal.