INTEGRATED CIRCUIT DEVICE OF SEMICONDUCTOR MEMORY

摘要

PURPOSE:To exclude the extra IC and single element and to improve the packing density of a memory by providing a power supply back-up circuit within a chip to back up a main power supply when it is cut off. CONSTITUTION:An IC memory chip 21 contains a switch circuit 2 which performs a switch between a main power supply and a battery power supply in addition to a memory 4. A power supply cut-off detecting circuit 1, a memory activation control circuit 3 and a battery power source VB of a back-up circuit are provided outside. The power supply VB is added by any one of connection to outside, lamination on the same chip 8 or incorporation into the same package. Thus it is possible to hold the memory information despite the cut-off of the power supply without adding a power supply back-up circuit to the outside of an IC device. An activating signal 122 of the memory in this example can vary the number of logic stages in accordance with a positive logic state or a negative logic state.