METHODS FOR ROW HAMMER MITIGATION AND MEMORY DEVICES AND SYSTEMS EMPLOYING THE SAME
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 system, comprising:
a memory device comprising a memory bank; and
a controller configured to cause the system to:
monitor a rolling accumulative activations (RAA) counter associated with a quantity of activate commands issued on the memory bank; and
issue a refresh management command to the memory bank based at least in part on a value of the RAA counter exceeding a threshold stored at one or more bits of a mode register, the refresh management command associated with allowing additional time for the memory device to manage refresh operations.
2 . The system of claim 1 , wherein the threshold comprises a rolling accumulated activations initial management threshold (RAAIMT).
3 . The system of claim 1 , wherein the refresh management command comprises a per-bank refresh command for refreshing the memory bank.
4 . The system of claim 1 , wherein the controller is further configured to cause the system to:
decrement the RAA counter based at least in part on issuing the refresh management command.
5 . The system of claim 4 , 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).
6 . The system of claim 1 , wherein the controller is further configured to cause the system to:
periodically issue refresh commands to the memory device at a multiple of a refresh interval.
7 . The system of claim 1 , wherein the controller is further configured to cause the system to:
maintain a second counter associated with a quantity of refresh operations scheduled for the memory bank.
8 . The system of claim 1 , wherein the memory device comprises a dynamic random access memory (DRAM) device.
9 . The system of claim 1 , wherein issuing the refresh management command is based at least in part on a bit of the mode register indicating that additional refresh management is required.
10 . A system, comprising:
a memory device comprising a memory bank; and
a controller configured to cause the system to:
monitor a rolling accumulative activations (RAA) counter associated with a quantity of issued activate commands issued on the memory bank; and
issue a refresh management command to the memory bank based at least in part on a value of a read-only bit stored in a mode register indicating that refresh management is required and determining that the RAA counter exceeds an RAA initial management threshold (RAAIMT).
11 . The system of claim 10 , wherein the controller is further configured to cause the system to:
decrement the RAA counter based at least in part on issuing the refresh management command.
12 . The system of claim 11 , wherein the RAA counter is decremented by a value of the RAAIMT threshold multiplied by a decrement value.
13 . The system of claim 11 , wherein the RAA counter is configured to not exceed a RAA maximum management threshold (RAAMMT).
14 . The system of claim 13 , wherein a value of the RAAMMT is based at least in part on one or more bits stored at the mode register.
15 . A memory device, comprising:
a set of memory banks; and
circuitry configured to cause the memory device to:
receive a periodic refresh command based at least in part on a refresh interval; and
receive 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 the set of memory banks exceeding a threshold stored at one or more bits of a mode register.
16 . The memory device of claim 15 , wherein the threshold comprises a rolling accumulated activations initial management threshold (RAAIMT).
17 . The memory device of claim 15 , wherein the refresh management command comprises a per-bank refresh command for refreshing the first memory bank.
18 . The memory device of claim 15 , wherein the circuitry is further configured to cause the memory device to:
decrement the RAA counter based at least in part on issuing the refresh management command.
19 . The memory device of claim 18 , 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).
20 . The memory device of claim 15 , wherein the circuitry is further configured to cause the memory device to:
maintain a second counter associated with a quantity of refresh operations scheduled for the first memory bank.