A touch sensing system and a method of controlling power consumption thereof are disclosed. The touch sensing system includes a plurality of sensing units, which sample a voltage received from a touch screen and accumulate the sampled voltage, and a plurality of analog-to-digital converters converting an output of the sensing units into digital data. The sensing units and the analog-to-digital converters are divided into a plurality of groups in an idle state. Each of the plurality of groups includes at least two sensing units and one analog-to-digital converter. At least one sensing unit included in at least one group is powered down in the idle state. An analog-to-digital converter is powered on during the group it belongs to is powered on.