| 摘要 |
PURPOSE: To back up a memory surely with less circuits without using another power supply for charging. CONSTITUTION: A memory back-up control has a memory, at least two secondary batteries 2, 3, and a supply voltage detecting means 1. It also has a connection switching means 4 which connects the secondary batteries 2, 3 in parallel and then charges the memory when the supply voltage detected by the supply voltage detecting means 1 is a specified level or above and which connects the secondary batteries 2, 3 in series and then supplies backup power to the memory through a step-down circuit 6. |
