Semiconductor memory device and memory system including the same

Abstract

A semiconductor memory device, including a memory cell array; a row hammer management circuit configured to: count a number of accesses based on an active command, and based on a first command applied after the active command, perform an internal read-update-write operation to read the count data from the count cells of a target memory cell row, and to write updated count data in the count cells of the target memory cell row; and a column decoder configured to: access a first memory cell using a first bit-line; and store data in the first memory cell using a first voltage, or perform an internal write operation to store the count data in the first memory cell using a second voltage greater than the first voltage during an internal write time interval smaller than a reference write time interval.