Touch screen controller, touch screen system including the touch screen controller, and method of operating the touch screen controller

Provided are a touch screen controller, a touch screen system including the touch screen controller, and a method of operating the touch screen controller. The touch screen controller includes a driving circuit configured to output a first driving signal in a first touch mode and a second driving signal in a second touch mode, the first touch mode including a driving period and a subsequent sensing period; and a boosting circuit configured, in the first touch mode, to generate a first voltage by performing an internal switching operation based on an input voltage and a first switching signal, and configured to provide the first voltage to the driving circuit, wherein the first switching signal has a first frequency in the driving period and a second frequency different from the first frequency in the subsequent sensing period.