Phase-change random access memories, memory devices, memory systems, methods of operating and methods of manufacturing the same

A semiconductor memory device comprising:

• a memory cell;
• a writing driver configured to write data to the memory cell by providing a program current to the memory cell;
• a sense amplifier configured to perform a read operation to read data stored in the memory cell;
• and
• a controller configured to provide a rewriting signal to the writing driver after the sense amplifier performs N number of read operations, where N is a positive integer;
• wherein
• the rewriting signal is for rewriting data read by the sense amplifier to the memory cell, and
• the program current is less than or equal to about 0.75 mA.