SEMICONDUCTOR DEVICE

PROBLEM TO BE SOLVED: To select operations of a built-in interface circuit in response to an initialization operation from a host device coupled thereto. SOLUTION: A semiconductor device includes: a first clock-synchronous interface circuit (30); and a second clock-asynchronous interface circuit (31) using differential signals, and shares the external terminals of the differential signals (the external differential signal terminals). For example, the semiconductor device adopts an MMC interface circuit as the first interface circuit and a USB interface circuit as the second interface circuit, while keeping the IC card interface function. The semiconductor device (20) selects operations of the adopted interface circuits exclusively. One selection method is to enable an interface operation of the first interface circuit, upon detection of a plurality of edge changes in a clock input given from an external clock terminal (C6), which is for initializing the first interface circuit when power supply to the semiconductor device 20 is started. COPYRIGHT: (C)2009,JPO&INPIT