| 摘要 |
PURPOSE:To back a memory up through a primary battery with a small output voltage and to prevent a current from flowing reversely to the primary battery from the apparatus power supply side by preventing charging of a second power supply part normally through a diode and by melting of a fuse at the time of failure of said diode. CONSTITUTION:A reverse-current prevention diode D2 is inserted in series with the output of a primary battery 2 so that a counterelectromotive force by the primary battery 2 is not generated in an apparatus body when an apparatus power supply is placed in OFF state. Also, a reverse current prevention diode D1 is in serted in series with the output of the apparatus power supply. Further, even if the diode D1 gets out of order, a fuse 3 is prevented from melting so that a reverse current ICC does not flow into the primary battery 2, because the fuse 3 is inserted in series with the output of the apparatus power supply. |
