BACK-UP MEMORY FOR ELECTRONIC EQUIPMENT

摘要

PURPOSE:To ensure the writing of data when a voltage drop is detected by performing the writing control of the prescribed data to a memory means when the voltage of a low level is detected and only when a period when no voltage drop is detected is longer than the charging time of a back-up power supply part. CONSTITUTION:An arithmetic control means 9 performs no writing control to a memory means 8, if a period when the drop is not detected for the power supply voltage counted by a clocking means 11 does not exceed the charging time of a back-up power supply part 10 for the satisfactory writing control in case the voltage of a low voltage is detected by a low voltage detecting means 7. As a result, the writing control is carried out only when the part 10 is satisfactorily charged. Thus, it is possible to avoid the writing failure of the prescribed data to the means 8 due to the drop of the voltage level of the part 10.