Methods for row hammer mitigation and memory devices and systems employing the same
View Patent ↗A method of operating a memory device is provided, comprising determining a number of operations corresponding to a memory location during a first timing period; and scheduling an extra refresh operation for the memory location after the first timing period when the determined number of operations exceeds a predetermined threshold. A memory device is provided, comprising a memory including a memory location; and circuitry configured to: determine a number of operations corresponding to the memory location during a first timing period; and schedule an extra refresh operation for the memory location after the first timing period when the determined number of operations exceeds a predetermined threshold.
1. A method, comprising:
issuing a periodic refresh management command to a memory device based at least in part on a refresh interval;
monitoring a rolling accumulative activations (RAA) counter associated with a quantity of activate commands issued on a memory bank of the memory device; and
issuing a non-periodic refresh management command to the memory device based at least in part on a value of the RAA counter, the refresh management command associated with allowing additional time for the memory device to manage refresh operations.
2. The method of claim 1 , wherein issuing the non-periodic refresh management command is based at least in part on the value of the RAA counter exceeding a threshold value.
3. The method of claim 2 , wherein the threshold value comprises a rolling accumulated activations initial management threshold (RAAIMT).
4. The method of claim 1 , wherein the non-periodic refresh management command comprises a per-bank refresh management command for refreshing the memory bank.
5. The method of claim 1 , further comprising:
decrementing the RAA counter based at least in part on issuing the non-periodic refresh management command.
6. The method of claim 5 , wherein the RAA counter is decremented by an amount that is based at least in part on a rolling accumulated activations initial management threshold (RAAIMT).
7. The method of claim 1 , wherein the non-periodic refresh management command comprises a refresh management command.
8. The method of claim 1 , wherein issuing the periodic refresh command further comprises:
periodically issuing periodic refresh commands to the memory device at a multiple of the refresh interval.
9. The method of claim 1 , further comprising:
maintaining a second counter associated with a quantity of refresh operations scheduled at the memory bank.
10. The method of claim 1 , wherein the memory device comprises a dynamic random access memory (DRAM) device.
11. The method of claim 1 , wherein issuing the periodic refresh command is based at least in part on a bit of a mode register, the bit indicating that additional refresh management is required.
12. A method, comprising:
monitoring a rolling accumulative activations (RAA) counter associated with a quantity of issued activate commands;
determining that the RAA counter exceeds a RAA initial threshold (RAAIMT) stored in a set of read-only bits of a mode register; and
issuing a refresh management command to a memory device based at least in part on a value of a read-only bit stored in the mode register indicating that refresh management is required and determining that the RAA counter exceeds the RAAIMT.
13. The method of claim 12 , further comprising:
decrementing a value of the RAA counter by the RAAIMT value multiplied by a decrement value.
14. The method of claim 12 , wherein the RAA counter is configured so as to not exceed a RAA maximum management threshold (RAAMMT).
15. The method of claim 12 , wherein the RAAMMT is based on one or more bits stored in the mode register.
16. A method at a memory device, comprising:
receive, from a controller, a periodic refresh command based at least in part on a refresh interval; and
receive, from the controller, a non-periodic refresh management command based at least in part on a value of a rolling accumulative activations (RAA) counter associated with a quantity of activate commands issued on a first memory bank of a set of memory banks of the memory device.
17. The method of claim 16 , wherein receiving the non-periodic refresh management command is based at least in part on the value of the RAA counter exceeding a threshold value.
18. The method of claim 17 , wherein the threshold value comprises a rolling accumulated activations initial management threshold (RAAIMT).
19. The method of claim 16 , wherein the non-periodic refresh management command comprises a per-bank refresh command for refreshing the first memory bank.
20. The method of claim 16 , wherein the RAA counter is decremented by an amount that is based at least in part on a rolling accumulated activations initial management threshold (RAAIMT).