The invention relates to a switch transformation IC (Integrated Circuit), and particularly but not exclusively relates to a switch transformation IC (Integrated Circuit) with a built-in photosensitive element. The switch transformation IC comprises a switch transformation circuit and an integrated photosensitive element, wherein the integrated photosensitive element is used for controlling the feedback to the switch transformation circuit. The demand on independent pins for periphery equipment for receiving feedback control information from external photosensitive elements is eliminated.