Generally, each integrated circuit (IC) provides multiple operational modes. The operational mode of an IC is usually configured at the power on or reset, so as to ensure the IC could start operating with the correct operational mode. Normally during initialization, the initial state of the IC is determined by providing working voltage or ground voltage to a plurality of specific pins of the IC. Thus, when the operational modes provided by the IC are increased, the number of pins of the IC will also be increased in response to the configuration of operational modes. For the IC design, the more pins the IC has, the larger volume the IC has, relatively. Therefore, how to reduce the pin numbers required by the initialization of IC is still a target each engineer is aggressively developing on. The related techniques and research could be referred to U.S. Pat. No. 6,831,479 and Taiwan Patent publication No. 200633381.