Semiconductor device and semiconductor system

A semiconductor device and a semiconductor system are provided. A semiconductor device includes a monitoring circuit receiving a first operating voltage and a second operating voltage, which is different from the first operating voltage, from a Power Management Integrated Circuit (PMIC) and monitoring a duration of use of a System-on-Chip (SoC) at each of the first and second operating voltages; a processing circuit calculating a normalized value based on predetermined weight information from the duration of use of the SoC at each of the first and second operating voltages; and a voltage circuit determining whether to increase an operating voltage of the SoC by comparing the normalized value with a predetermined value.