Semiconductor device that performs refresh operation
View Patent ↗To include a refresh control circuit that generates a refresh execution signal in response to a refresh command supplied from outside, and a refresh address counter that performs a counting operation in response to activation of the refresh execution signal. The refresh control circuit generates the refresh execution signal 2 n times in response to one supply of the refresh command, where n is an integer equal to or larger than 0 and equal to or less than k. The value of n is variable based on a refresh-mode specifying signal supplied from outside in synchronization with the refresh command. With this configuration, for example, a frequency of generation of the refresh execution signal in response to one supply of the refresh command can be changed dynamically, flexible control can be performed by a controller.
1. A semiconductor device comprising:
a refresh control circuit that generates a refresh execution signal in response to a refresh command issued from outside;
a refresh address counter that updates a refresh address in response to the refresh execution signal; and
a first circuit that receives the refresh command and a first signal, the first signal supplied from outside in synchronization with the refresh command, and generates a refresh-mode specifying signal based on the refresh command and the first signal, and outputs a refresh-mode specifying signal to the refresh control circuit, wherein
the refresh control circuit generates the refresh execution signal 2 n times each time when the refresh command is issued, where n is an integer equal to or larger than 0 , and
the refresh control circuit changes a value of n based on the refresh-mode specifying signal.
2. The semiconductor device as claimed in claim 1 , further comprising a plurality of memory cells storing information that is refreshed according to the refresh execution signal and the refresh address, wherein
a number of bits constituting the refresh address counter is m+k when the value of n is k, and when number of times the refresh command needs to be supplied for refreshing all the memory cells is 2 m , where m is a natural number.
3. The semiconductor device as claimed in claim 1 , wherein the refresh address counter performs one counting operation each time when the refresh execution signal is activated regardless of the value of n.
4. The semiconductor device as claimed in claim 1 , further comprising a first mode register, wherein the refresh control circuit enables or disables the refresh-mode specifying signal based on information stored in the first mode register.
5. The semiconductor device as claimed in claim 4 , wherein the refresh control circuit generates the refresh execution signal 2 k times each time when the refresh command is issued when the refresh-mode specifying signal is disabled, and n is equal to or less than k.
6. The semiconductor device as claimed in claim 4 , further comprising a second mode register, wherein
the second mode register stores information specifying the value of n.
7. The semiconductor device as claimed in claim 6 , wherein
the first signal is a 1-bit signal, and
the refresh control circuit sets the value of n as a value set in the second mode register when the refresh-mode specifying signal is enabled based on the information in the first mode register and the refresh-mode specifying signal is in a first logic level.
8. The semiconductor device as claimed in claim 7 , wherein the refresh control circuit sets the value of n to the k when the refresh-mode specifying signal is enabled based on the information in the first mode register and the refresh-mode specifying signal is in a second logic level.
9. The semiconductor device as claimed in claim 1 , further comprising a temperature detection circuit that measures a temperature and activates a temperature detection signal when the measured temperature is lower than a predetermined temperature, wherein
the refresh control circuit reduces number of generations of the refresh execution signal to less than number of generations indicated by the n when the temperature detection signal is in an active state.
10. The semiconductor device as claimed in claim 1 , wherein the plurality of memory cells belonging to different memory banks that are mutually non-exclusively controlled are refreshed each time when the refresh execution signal is activated.
11. A semiconductor device comprising:
a refresh control circuit that generates a refresh execution signal in response to a refresh command issued from outside; and
a memory cell array including a plurality of memory cells that are refreshed in response to the refresh execution signal, wherein
the refresh control circuit generates the refresh execution signal 2 n times each time when the refresh command is issued, when number of times the refresh command is issued in a predetermined period is 2 m+k−n where m is a natural number and n is an integer equal to or larger than 0 and equal to or less than k.
12. The semiconductor device as claimed in claim 11 , further comprising a refresh address counter that performs a counting operation in response to the refresh execution signal, wherein
a number of bits constituting the refresh address counter is m+k.
13. The semiconductor device as claimed in claim 11 , wherein the refresh control circuit changes a value of n according to a refresh-mode specifying signals supplied from outside in synchronization with the refresh command.
14. The semiconductor device as claimed in claim 13 , further comprising a first mode register that indicates whether the refresh-mode specifying signal is to be enabled or disabled.
15. The semiconductor device as claimed in claim 14 , wherein the refresh control circuit generates the refresh execution signal 2 k times each time when the refresh command is issued when the refresh-mode specifying signal is disabled based on information in the first mode register.
16. The semiconductor device as claimed in claim 14 , further comprising a second mode register that indicates the value of n.
17. The semiconductor device as claimed in claim 16 , wherein
the refresh-mode specifying signal is a 1-bit signal, and
the refresh control circuit sets the value of n as a value indicated in the second mode register when the refresh-mode specifying signal is enabled based on information in the first mode register and the refresh-mode specifying signal is in a first logic level.
18. The semiconductor device as claimed in claim 17 , wherein the refresh control circuit sets the value of n to the k when the refresh-mode specifying signal is enabled based on the information in the first mode register and the refresh-mode specifying signal is in a second logic level.
19. The semiconductor device as claimed in claim 11 , further comprising a temperature detection circuit that measures a temperature and activates a temperature detection signal when the measured temperature is lower than a predetermined temperature, wherein
the refresh control circuit reduces number of generations of the refresh execution signal to less than number of generations indicated by the n when the temperature detection signal is in an active state.
20. The semiconductor device as claimed in claim 11 , wherein the plurality of memory cells belonging to different memory banks that are mutually non-exclusively controlled are refreshed each time when the refresh execution signal is activated.
21. The semiconductor device as claimed in claim 12 , wherein the refresh control circuit changes a value of n according to a refresh-mode specifying signals supplied from outside in synchronization with the refresh command.
22. The semiconductor device as claimed in claim 21 , further comprising a first mode register that indicates whether the refresh-mode specifying signal is to be enabled or disabled.
23. The semiconductor device as claimed in claim 22 , wherein the refresh control circuit generates the refresh execution signal 2 k times each time when the refresh command is issued when the refresh-mode specifying signal is disabled based on information in the first mode register.
24. The semiconductor device as claimed in claim 22 , further comprising a second mode register that indicates the value of n.
25. The semiconductor device as claimed in claim 24 , wherein
the refresh-mode specifying signal is a 1 -bit signal, and
the refresh control circuit sets the value of n as a value indicated in the second mode register when the refresh-mode specifying signal is enabled based on information in the first mode register and the refresh-mode specifying signal is in a first logic level.
26. The semiconductor device as claimed in claim 25 , wherein the refresh control circuit sets the value of n to the k when the refresh-mode specifying signal is enabled based on the information in the first mode register and the refresh-mode specifying signal is in a second logic level.
27. The semiconductor device as claimed in claim 12 , further comprising a temperature detection circuit that measures a temperature and activates a temperature detection signal when the measured temperature is lower than a predetermined temperature, wherein
the refresh control circuit reduces number of generations of the refresh execution signal to less than number of generations indicated by the n when the temperature detection signal is in an active state.
28. The semiconductor device as claimed in claim 12 , wherein the plurality of memory cells belonging to different memory banks that are mutually non-exclusively controlled are refreshed each time when the refresh execution signal is activated.