公开(公告)号：JP2002123339A

公开(公告)日：2002-04-26

申请号：JP2001227734

申请日：2001-07-27

Applicant: ST MICROELECTRONICS INC

Inventor： MCCLURE DAVID C ,  YOUSSEF TOM

IPC: G06F1/26 ,  G01R23/16 ,  G08B21/00 ,  G11C5/14 ,  H03K17/00

Abstract: PROBLEM TO BE SOLVED: To provide a technology for switching from a primary power source to a secondary power source without loosing data stored from a volatile element. SOLUTION: This integrated circuit has a forcible power source switching circuit which detects the supply level of the primary power source dropping below a predetermined threshold level. The switching circuit on the integrated circuit starts switching operation once the forcible power source switching circuit detects the supply level received from the primary power source dropping the predetermined threshold level. The detection by the forcible power source switching circuit can be generated at a signal level having faster transition than a specific negative variation rate. This integrated circuit can be built in an arbitrary system equipped with a memory or a volatile element such as a clock.