Apparatuses and methods for staggered timing of skipped refresh operations
Embodiments of the disclosure are drawn to apparatuses and methods for staggering the timing of skipped refresh operations on a memory. Memory cells of memories may need to periodically perform refresh operations. In some instances, auto-refresh operations may be periodically skipped when charge retention characteristics of the memory cells of the memory exceed the auto-refresh frequency. To reduce peak current draw during refresh operations, the skipped refresh operations may be staggered across different portions of the memory. In one example, the skipped refresh operation may be staggered in time among memory dies of the memory to limit a number of memory dies that are performing an auto-refresh operation to a maximum number. In another example, the skipped refresh operation may be staggered in time among memory banks of a single memory array to limit a number of memory banks that are performing an auto-refresh operation to a maximum number.
1. An apparatus comprising:
a first memory die comprising a first plurality of rows of memory cells, wherein, responsive to a first activation of a refresh signal, the first memory die is configured to perform an auto-refresh operation on a first subset of the first plurality of rows of memory cells, wherein, responsive to a second activation of the refresh signal, the first memory die is further configured to either perform a first targeted refresh operation on a first row hammer attack victim row of the first plurality of memory cells or skip a refresh operation; and
a second memory die comprising a second plurality of rows of memory cells, wherein, responsive to the first activation of the refresh signal, the second memory die is configured to either perform a second targeted refresh operation on a second row hammer attack victim row of the second plurality of rows of memory cells or skip a refresh operation, wherein, responsive to the second activation of the refresh signal, the second memory die is further configured to perform an auto-refresh operation on a second subset of the second plurality of rows of memory cells.
2. The apparatus of claim 1 , wherein the first memory die and the second memory die are both configured to contemporaneously perform respective targeted refresh operations responsive to a third activation of the refresh signal.
3. The apparatus of claim 1 , wherein, responsive to the second activation of the refresh signal, the first memory die is configured to perform the first targeted refresh operation in response to detection of a first row hammer attack associated with the first victim row.
4. The apparatus of claim 3 , wherein the first memory die is configured to skip a refresh operation when no row hammer attack is detected.
5. The apparatus of claim 3 , wherein the first memory die is configured to detect the first row hammer attack.
6. The apparatus of claim 1 , further comprising a memory package that includes the first memory die and the second memory die.
7. The apparatus of claim 1 , further comprising a memory module that includes the first memory die and the second memory die.
8. The apparatus of claim 1 , wherein the first memory die is configured to determine whether to perform the auto-refresh operation or to either perform the first targeted refresh operation or skip a refresh operation based on an internal setting.
9. The apparatus of claim 8 , wherein the first memory die is configured to determine the internal setting is based on a value programmed in a fuse bank.
10. The apparatus of claim 8 , wherein the first memory die comprises a refresh address control circuit configured to determine a pattern of auto-refresh operations and targeted or skipped refresh operations based on the internal setting.
11. An apparatus comprising:
a memory array having a plurality of memory banks;
a refresh control circuit configured to receive a refresh signal, wherein, in response to each activation of the refresh signal, the refresh control circuit is configured to cause an auto-refresh operation to be staggered across the plurality of memory banks such that the auto-refresh operation is skipped for a different subset of less than all of the plurality of memory banks for each activation of the refresh signal.
12. The apparatus of claim 11 , wherein the refresh control circuit is configured to cause auto-refresh operations to be skipped on the plurality of memory banks at a common frequency.
13. The apparatus of claim 11 , wherein the refresh control circuit is configured to cause auto-refresh operations to be skipped for a particular subset of memory banks based on a corresponding counter having a target count value.
14. The apparatus of claim 13 , wherein the refresh control circuit is configured to cause auto-refresh operations to be skipped for a second particular subset of memory banks based on a second corresponding counter having a second target count value.
15. The apparatus of claim 13 , wherein the refresh control circuit is configured to initialize the counter to and the second counter to different values.
16. The apparatus of claim 13 , wherein the refresh control circuit is configured to adjust a count value of the counter in response to activations of the refresh signal.
17. The apparatus of claim 11 , wherein, in response to an activation of the refresh signal, the refresh control circuit is configured to cause a particular memory bank of the plurality of memory banks to perform a targeted refresh operation responsive to detection of a row hammer attack associated with the particular memory bank.
18. A method comprising:
receiving a refresh signal at a memory having a memory array with a plurality of memory banks;
in response to a first activation of the refresh signal:
performing an auto-refresh operation on a first subset of less than all of the plurality of memory banks; and
skipping a refresh operation on a second subset of less than all of the plurality of memory banks, wherein the first subset of less than all of the plurality of memory banks and the second subset of less than all of the plurality of memory banks are each mutually exclusive subsets of the plurality of memory banks; and
in response to a second activation of the refresh signal:
performing an auto-refresh operation on the second subset of the plurality of memory banks; and
skipping a refresh operation on the first subset of the plurality of memory banks.
19. The method of claim 18 , further comprising skipping the auto-refresh operations on the first subset and the second subset of the plurality of memory banks at a common frequency.
20. The method of claim 18 , further comprising in response to a second activation of the refresh signal, skipping the refresh operation on the first subset of the plurality of memory banks when a counter has a target count value.
21. The method of claim 20 , further comprising in response to the first activation of the refresh signal, skipping the refresh operation on the second subset of the plurality of memory banks when a second counter has a second target count value.