| 摘要 |
PURPOSE: A backup circuit for preventing memory erasure is provided to prevent data stored on SRAM from being erased due to a transition condition of a system power source when the system power source is turned on or off, by supplying a backup power source to SRAM during the system power source failure. CONSTITUTION: A current input part(10) transfers a current of system power source Vcc provided externally. A current switching part(30) switches the current of the system power source Vcc fed thereto through the current input part(10). An adjustment part(20), responsive to the current applied thereto from the current input part(10) and a chip selection enable signal CSE provided thereto from a central processing unit, adjusts the operation of the current switching part(30). A battery power source (40) provides the current as an erasure prevent current to the SRAM and charges a battery with the current, when the system power source Vcc is applied through the current switching part(30); provides the charged current as the erasure prevent current to the SRAM, when the system power source Vcc is not applied through the current switching part(30).
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