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US 2009/0022002 A1Published application
Semiconductor memory device
AssigneeFujitsu Limited
InventorAtsumasa Sako
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AssigneeFujitsu Limited
InventorAtsumasa Sako
Estimating the term…
A semiconductor memory device is provided for minutely changing a refresh interval according to a detected temperature and thereby lowering its power consumption. A temperature detector detects a temperature of a chip and outputs the corresponding temperature signal. A reference temperature signal output unit outputs the corresponding reference temperature signal with each of different reference temperatures to be compared with the chip temperature according to a selection signal. A temperature comparison unit compares the chip temperature with the reference temperature through the temperature signal and the reference temperature signal. A selection signal output unit outputs the selection signal according to the compared result of the temperature comparison unit. A refresh interval control unit changes the refresh interval according to the compared result of the temperature comparison unit.
1-8. (canceled)
A method of changing a refresh frequency in a semiconductor memory device, comprising:
The method according to claim 1, wherein the refresh frequency is set to higher at higher temperature and the refresh frequency is set to lower at lower temperature.
The method according to claim 1, further comprising:
The method according to claim 1, further comprising:
The method according to claim 1, wherein the plurality of different reference temperature signals are generated based on a voltage that does not depend on a variations of the temperature and a power supply.
The method according to claim 1, wherein each of the plurality of different reference temperature signals corresponds to one of a plurality of temperatures which are set by incrementing a start temperature by a certain value until reaching a end temperature.
The method according to claim 1, further comprising:
A method of changing an interval period between a refresh operation in a semiconductor memory device, comprising:
The method according to claim 8, wherein the interval refresh is set to shorter at higher temperature and the interval refresh is set to longer at lower temperature.
The method according to claim 8, further comprising:
The method according to claim 8, further comprising:
The method according to claim 8, wherein the plurality of different reference temperature signals are generated based on a voltage that does not depend on a variations of the temperature and a power supply.
The method according to claim 8, wherein each of the plurality of different reference temperature signals corresponds to one of a plurality of temperatures which are set by incrementing a start temperature by a certain value until reaching a end temperature.
The method according to claim 8, further comprising:
Dependencies are inferred from the claim text.