Semiconductor memory device and method of controlling the same
AssigneeNEC Corporation
InventorAtsunori Miki
Life of this patent
Estimating the term…
Abstract
A semiconductor memory device includes a plurality of memory blocks formed of a flash memory. The semiconductor memory device further includes a rewriting monitor circuit for memorizing the number of times of data rewriting in each of the memory blocks, and a switching circuit for switching a memory block selection address. When the number of times of rewriting in a first memory block which is a rewriting request object exceeds a predetermined value, data in a second memory block is transferred to the first memory block. Data to be written is written to the second memory block. Therefore, it is possible to increase the number of times of rewriting in the flash memory.
Claims9
A semiconductor memory device, comprising:
- a data memory unit having a plurality of memory blocks;
- a rewriting monitor circuit for memorizing the number of times of data rewriting in each of the memory blocks, the rewriting monitor circuit being a nonvolatile memory device;
- a block address switching circuit for switching a block selection address;
- a temporary memory circuit for temporarily retaining data memorized in a predetermined block;
- a control unit for controlling a data transfer;
- and a rewriting inhibition information memory circuit for memorizing rewriting inhibition information on each of the memory blocks.
A method of controlling a semiconductor memory device, comprising the steps of:
- erasing data in a first memory block based on a rewriting request;
- acquiring the number of times of rewriting in each memory block;
- writing, to a temporary memory circuit, data in a second memory block in which the number of times of rewriting is equal to a predetermined value or less, when the number of times of rewriting in the first memory block, in which the data is erased, exceeds the predetermined value;
- erasing the data in the second memory block;
- changing a memory block address to memorize it;
- transferring the data stored in the temporary memory circuit to the first memory block;
- and
- writing data to be rewritten to the second memory block.
Dependencies are inferred from the claim text.