CONTROLLER AND CONTROL METHOD

摘要

According to one embodiment, a controller controls a nonvolatile memory stores data page by page. The controller is configured to extract, from a first data sequence shorter than the data length of a page, a second data sequence shorter than the first data sequence, to refer to the difference between threshold voltages corresponding to two data included in the second data sequence, to convert the second data sequence into a third data sequence longer than the second data sequence, and to control the percentage of the length of an error correction code added to the third data sequence.

主权项

1. A controller of a nonvolatile memory configured to store n-level (n is a natural number not less than three) data page by page, the controller comprising:
an extraction unit configured to extract, from a first data sequence with a first data length shorter than a data length of a page, a second data sequence with a data length shorter than the first data sequence; a conversion unit configured to convert the second data sequence into a third data sequence which is longer than the second data sequence and includes a second level difference smaller than a first level difference, when a difference between threshold voltages corresponding to two adjacent data included in the second data sequence is the first level difference; a control unit configured to control a percentage of a length of an error correction code added to the third data sequence; and an error correction encoder configured to generate the error correction code under control of the control unit.