Patent ID: 8621139

Claim:
A data writing method, for writing data into a block of a multi-level cell (MLC) NAND flash memory, wherein the block comprises a plurality of page addresses, the page addresses are categorized into a plurality of upper page addresses and a plurality of lower page addresses, and the writing speed of the lower page addresses is faster than the writing speed of the upper page addresses, the data writing method comprising: (1) receiving a writing command and data to be written; (2) obtaining a first page address from the block; (3) determining whether the first page address belongs to the lower page addresses of the block, wherein step (5) is executed if the first page address belongs to the lower page addresses of the block, and step (4) is executed if the first page address does not belong to the lower page addresses of the block; (4) determining whether a second page address, which belongs to the lower page addresses of the block and has a coupling relationship with the first page address, stores valid data written by a previous writing command, wherein if the second page address does not store the valid data written by the previous writing command, step (5) is executed, and if the second page address stores the valid data written by the previous writing command, step (6) is executed; (5) writing the data into the first page address; and (6) skipping the first page address and writing the data into a third page address, which belongs to the lower page addresses of the block and does not have the coupling relationship with the first page address, wherein the skipped first page address does not store data before the block is erased.