| 摘要 |
PROBLEM TO BE SOLVED: To reduce a consumption current during backup of a volatile memory more as a data amount stored in the volatile memory decreases. SOLUTION: After a main power supply 2 is turned off, at first, a memory data monitoring unit 9 monitors the entire capacity and the use capacity of a data area (memory area) of a volatile memory 8 to confirm the use state as the use capacity of the entire capacity obtained by monitoring, and a system control unit 7 confirms if the use state is any of 1/8 or more, 1/4 or more, 1/2 or more, and 3/4 or more. Depending on the confirmation result, a self refresh state is set up to an area where data used in a portion of a data array of the least use state is completely contained, and a power supply control circuit 5 exerts control so that a current is supplied from an auxiliary power supply 3 through a power supply circuit 6. COPYRIGHT: (C)2011,JPO&INPIT |
