Memory backup circuit and memory backup method
First Claim
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1. A memory backup circuit comprising:
- a memory for storing data to be processed;
identifying means for identifying whether or not useful data is stored in said memory;
a backup battery which is charged while a main power supply is supplying current;
power supply supervising means for changing selection between the main power supply and said backup battery as a current supply source to said memory; and
backup control means for controlling whether or not to discharge current from said backup battery when the main power supply ceases supplying current, wherein said backup control means sets said backup battery in a dischargeable state when said identifying means has determined that useful data is stored in said memory, and sets said backup battery in a non-dischargeable state when said identifying means has determined that no useful data is stored in said memory.
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Abstract
A change over unit 12 is controlled to become conductive only when useful data is stored in a memory 15 for storing data to be processed. Therefore, when a main power supply is shut off, a memory backup function of a backup battery 13 is operated only when useful data is stored in the memory 15, thereby preventing unnecessary backup, which results in preventing the backup battery 13 from unnecessarily discharging and realizing a reliable memory backup.
17 Citations
12 Claims
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1. A memory backup circuit comprising:
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a memory for storing data to be processed; identifying means for identifying whether or not useful data is stored in said memory; a backup battery which is charged while a main power supply is supplying current; power supply supervising means for changing selection between the main power supply and said backup battery as a current supply source to said memory; and backup control means for controlling whether or not to discharge current from said backup battery when the main power supply ceases supplying current, wherein said backup control means sets said backup battery in a dischargeable state when said identifying means has determined that useful data is stored in said memory, and sets said backup battery in a non-dischargeable state when said identifying means has determined that no useful data is stored in said memory. - View Dependent Claims (2, 3, 10, 11, 12)
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4. A memory backup method for an information processing apparatus having a memory for storing data to be processed and a backup battery which is charged while a main power supply is supplying current, said method comprising the steps of:
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identifying whether or not useful data is stored in the memory; and setting the backup battery in a dischargeable state when it is identified that useful data is stored in the memory at said identifying step;
orsetting the backup battery in a non-dischargeable state when it is identified that no useful data is stored in the memory at said identifying step. - View Dependent Claims (5, 6, 7, 8, 9)
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Specification