Embodiments of the present disclosure relate to a touch controller, a touch sensing system, and a touch display device. Among data communication periods between the touch controller and a touch driving circuit, during the data communication period included in a period in which a system clock signal is not output, a level of a communication control signal is changed a plurality of times, thereby allowing the touch driving circuit to recognize an address start time point. Therefore, it is possible to reduce power consumption of the touch sensing system by reducing a period in which the system clock signal is output and to improve the efficiency of data communication of the touch sensing system by enabling normal data communication in a period in which the system clock signal is not output.