Semiconductor memory device and methods of operation

Abstract

A semiconductor memory device includes a memory cell array, a row hammer management circuit and a control logic circuit. The memory cell array includes a plurality of memory cell rows. The row hammer management circuit counts the number of instances of access of each of the memory cell rows, such as in response to the receipt of an active command, to store the counted values in count cells of each of the memory cell rows as count data and, in response to a first command, initiates an internal read-update-write operation to read the count data, to update the read count data, and to write the updated count data in the count cells. The control logic circuit may performs an internal write operation to write the updated count data in the count cells during a second write time interval that is smaller than a first write time interval associated with a normal write operation.