Semiconductor memory device having self-refresh function
AssigneesFujitsu Limited, Fujitsu VLSI Limited
InventorsMakoto Niimi, Shigemasa Ito, Toyonobu Yamada, Yoshihiro Takemae, Yoshiharu Kato
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Abstract
A semiconductor memory device has an oscillator unit for generating refresh pulses, a refresh address detection unit for detecting refreshed addresses and outputting a predetermined signal upon the completion of the refreshing of all addresses, and an output control unit for continuing a self-refresh mode to refresh all addresses according to the signal from the refresh address detection unit, before releasing the self-refresh mode in response to an external signal. Therefore, the refresh operation is continued until all cells are refreshed, thereby data stored in the semiconductor memory device is not lost and is correctly refreshed.
Claims4
A semiconductor memory device having plural memory cells with corresponding memory cell addresses and operative in a self-refresh mode for automatically refreshing the plural memory cells, comprising:
- oscillator means for generating pulse signals and providing the pulse signals as an output thereof;
- refresh address detection means for detecting refreshed memory cells of the plurality of memory cells and the corresponding addresses thereof and outputting a completion signal upon the completion of the refreshing of the respective memory cells of all of the memory cell addresses;
- and
- output control means responsive to a control signal for continuing the self-refresh mode thereby to refresh all memory cells of the respective memory cell addresses according to the completion signal from said refresh address detection means before releasing the self-refresh mode, the pulse signals output from said oscillator means being input to said output control means.
Dependencies are inferred from the claim text.