Memory system, operation method thereof and controller

A controller, wherein the controller is coupled to at least one memory device, the memory device comprises a memory cell array and a peripheral circuit coupled to the memory cell array, the memory cell array comprises a plurality of memory cells, and a preset number of memory cells in the plurality of memory cells form a codeword;

• and the controller is configured to:
• perform a read operation on a reference codeword to obtain a first result, and use the first result as a VT indicator, wherein the first result is configured to represent a number of bits that are flipped between two read results of the reference codeword at a first read voltage and a second read voltage, and a difference between the first read voltage and the second read voltage is less than a preset voltage;
• obtain at least one offset prediction according to the VT indicator in combination with a mapping table, wherein the mapping table comprises a mapping relationship between the VT indicator and the offset prediction;
• and
• determine a valley voltage according to the offset prediction, wherein the valley voltage is used as a read voltage for performing the read operation on a target codeword.

An operation method of a memory system, wherein the memory system comprises at least one memory device and a controller coupled to the memory device and configured to control the memory device, wherein the memory device comprises a memory cell array and a peripheral circuit coupled to the memory cell array, the memory cell array comprises a plurality of memory cells, and a preset number of memory cells in the plurality of memory cells form a codeword;

• and the operation method comprises:
• performing, by the peripheral circuit, a read operation on a reference codeword to obtain a first result, and using the first result as a VT indicator, wherein the first result is configured to represent a number of bits that are flipped between two read results of the reference codeword at a first read voltage and a second read voltage, and a difference between the first read voltage and the second read voltage is less than a preset voltage;
• obtaining, by the controller, at least one offset prediction according to the VT indicator in combination with a mapping table, wherein the mapping table comprises a mapping relationship between the VT indicator and the offset prediction;
• and
• determining a valley voltage according to the offset prediction, wherein the valley voltage is used as a read voltage for performing the read operation on a target codeword.