Semiconductor integrated circuit device having main power terminal and backup power terminal independently of each other.

摘要

A semiconductor integrated circuit device in which an internal circuit thereof is held by a backup power source when a main power source is disconnected comprises a comparator 29 for comparing a potential at a first power terminal 111 with that at a second power terminal 110. When the potential at the first power terminal is reduced switch means 212 connected between the first and second power terminals is closed to supply power from the second power terminal to a data storage unit 17 while forbidding write and read operations of store data. <IMAGE>