1. Technical Field
The embodiment described herein relates generally to a semiconductor memory apparatus, and more particularly to a flash memory apparatus and read operation control circuit, and method therefor.
2. Related Art
In general, flash memories are composed of a plurality of blocks and each of the blocks is composed of a plurality of pages. Further, read and write operations are performed in a page unit and an erasing operation is performed in a block unit.
In flash memory a corresponding page must be erased before data is recorded, and therefore recording data directly to the flash memories by using a data address generated from an application can cause failure.
FIG. 1 is a block diagram showing the configuration of a common flash memory apparatus.
As shown in the figure, a flash memory apparatus is configured to include a flash memory 10, an application 12 (e.g., a user program requesting a predetermined data calculation), a control unit 14 allowing data calculation to be executed in the flash memory 10 in accordance with the request of the application 12, and a driver 16 performing physical access to the flash memory 10.
In the configuration shown in FIG. 1, the control unit 14 is configured to include a file system 142 and Flash Translation Layer (FTL) 144.
The file system 142 manages files and directories to provide a user with more efficient storage device environment.
The FTL 144 allows the flash memory 10 to be used as a virtual block device, and therefore performs a function of mapping an address, that is, the FTL 144 converts a logic address transmitted from the application 12 into a physical address that is used in the flash memory 10.
Further, the FTL 144 performs a function of wear-leveling. As described above, the flash memory 10 cannot overwrite data, the existing data must be erased before performing a write operation. Over time, performing the erasing operating can deteriorate a flash memory, and when the erasing operation is performed more than a predetermined number of times, the corresponding block can no longer be used. Therefore, to extend the life span of a flash memory the erasing operation should be uniformly performed throughout the blocks of the flash memory, which can be achieved through wear-leveling. The FTL 144 manages the number of erasures for each block. Further, the FTL 144 allows the flash memory to sufficiently function as a disc by transferring data stored in blocks where the erasing operation has been performed many times to blocks where the erasing operation has not been performed as many times.
Small electronic devices, such as MP3 players, portable game machines, mobile communication terminals and the like commonly use Flash memories.
Small portable electronic devices, such as MP3 players, are not typically used for recording data in a memory, but rather the small portable electronic devices are used for repeatedly reading recorded data. Such repeated read operation of a memory causes electric current leakage and influences adjacent cells that a hot carrier did not access due to repeated read operations.
In flash memories, performing a write operation requires the application of a voltage of at least a predetermined level. In the flash memory, when repeatedly performing the read operation for a specific page, the voltages of the adjacent cells can increase by a predetermined level due to the hot carrier generated by the repeated read operation, which can bring the same result as writing data in the corresponding adjacent cells.
As a result, conventionally the data stored in a flash memory can be changed to an undesired value resulting in reading the wrong data in a later reading operation when repeatedly performing the read operation as described above.