of the semiconductor device the comparator 123 may determine that the count bit signals rod_out lt n 0 gt are greater than the predetermined reference bit signals default_set lt n 0 gt and output the driver set signals dqdrv_set lt m 0 gt corresponding to differences therebetween the output pre driver 124 may reduce the number of bit signals activated among the pull up bit signals pu lt m 0 gt and the pull down bit signals pd lt m 0 gt to less than the predetermined number based on the driver set signals dqdrv_set lt m 0 gt the output driver 125 may output data by controlling the voltage level of the external data line dq based on the pull up bit signals pu lt m 0 gt and the pull down bit signals pd lt m 0 gt which are output from the output pre driver 124 for example when the output pre driver 124 activates the pull up bit signals pu lt m 0 gt the output driver 125 may increase the voltage level of the external data line dq to a high level when the output pre driver 124 activates the pull down bit signals pd lt m 0 gt the output driver 125 may reduce the voltage level of the external data line dq to a low level as described above according to the embodiment of the present invention changes in internal conditions of the semiconductor device may be sensed by counting the dock number of the output clock rod_out which is output from the oscillator 121 and comparing the counted.