An operation method of a semiconductor device is disclosed. The semiconductor device includes separate first and second dies in a package and receives first types of signals through first and second respective channels independent of each other and corresponding to the first and second respective dies. The method includes a step in which when information for controlling internal operations of the first and second dies is first applied to the first die through a first pad, the first die performs the internal operation and also transmits the information to the second die through an internal interface connecting the first die and the second die, and a step in which when the information is transmitted to the second die, the second die performs the internal operation.