A touch screen controller circuit (1A) including means for generating a first and second levels of a pen touch signal (PENTOUCH) if a touch point (Q) is present or absent, respectively. A clock start signal (CLKSTART) is generated in response to the first level. An internal clock signal (INTCLK) is generated in response to the clock start signal. First and second levels of a synchronized pen touch signal (PENTOUCH1) corresponding to the first and second levels, respectively, of the pen touch signal are generated in response to the internal clock signal. A stop clock signal (CLKSTOP) is generated in response to the second level of the synchronized pen touch signal. The internal clock signal (INTCLK) is stopped in response to the clock stop signal.