Battery back-up system

PURPOSE: To produce a sequence signal for input of a battery back-up mode regardless of the voltage of a battery back-up system and to facilitate the use of a general-purpose power supply which does not output a power cut-off previous announcement signal. CONSTITUTION: A battery back-up system is provided with a DC/DC converter 3 which produces a working power supply of an SRAM 6 from the power voltage Vcc of the system. A voltage detecting circuit 1 is provided with a means (reset IC, etc.) which produces the timing signals (PD 1 , PD 2 ) for battery back-up based on the power voltage level of the system. COPYRIGHT: (C)1993,JPO&Japio