| CPC G11C 16/3459 (2013.01) [G11C 16/0433 (2013.01); G11C 16/102 (2013.01); G11C 16/20 (2013.01)] | 21 Claims |
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1. A memory system comprising:
a memory device including a plurality of memory blocks each including a plurality of word lines; and
a controller configured to:
store a plurality of default levels, which respectively correspond to the plurality of memory blocks, in an information storage region therein, and
perform a read operation on a selected word line of a selected block among the plurality of memory blocks,
wherein the read operation is performed by:
performing a read operation using a selected default level of the plurality of default levels, the selected default level corresponding to the selected block, and
performing, when the read operation using the selected default level fails, a read operation using an adjusted level smaller than the selected default level by a predetermined level, and
wherein the controller is further configured to:
reset the adjusted level to the selected default level when a number of times that the read operation using the adjusted level is passed is greater than a number of times that the read operation using the selected default level is passed by a reference number of times or more, and
store the reset level in the information storage region.
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