A semiconductor device for determining whether a foreign substance (e.g., water) is present and a method of operating the same are provided. The semiconductor device includes a receptacle including a plurality of pins according to a USB type-C receptacle interface; a first current source providing first current to a CC1 signal pin or a CC2 signal pin among the plurality of pins in a first operation mode; a second current source providing second current to the CC1 signal pin or the CC2 signal pin in a second operation mode; a third current source providing third current to at least two pins of other pins excluding the CC1 signal pin and the CC2 signal pin; and a power delivery integrated circuit (PDIC) controlling the first current source, the second current source and the third current source and detecting the voltage level of a signal outputted to the plurality of pins.