ELECTRONIC DEVICE EQUIPPED WITH DATA BACK UP FUNCTION

PROBLEM TO BE SOLVED: To provide an electronic device equipped with a data back up function which can select a battery without the use of an internal logic power source voltage. SOLUTION: The electronic device is equipped with; an internal logic power source 2 used as a circuit operation power source in the electronic device; a super capacitance 5 which is charged when the power source of the electronic device is turned on, and supplies power to an SRAM1 for data back up from immediately after power off; a battery 6 for back up of voltage higher than the voltage of the internal logic power source 2 and plus terminal voltage of the super capacitance 5 so that the electronic device does not consume a current when the power source is turned on and the super capacitance 5 is charged enough; a voltage monitoring IC 8 which detects a brownout of the super capacitance 5; and a battery power source on/off control circuit 14 which supplies power source to the SRAM1 from the battery 6 for back up by a brownout detection signal of the super capacitance 5 outputted from the voltage monitoring IC 8. COPYRIGHT: (C)2005,JPO&NCIPI