Memory devices and memory systems having the same

A memory system comprising:

• a memory device including,
• a cell array configured to receive data at an associated address in response to a write command,
• a storage unit configured to,
• receive the associated address and the data in response to the write command, and
• output the data to the associated address of the cell array in response to a rewrite command, and
• a violation determining unit configured to,
• determine data written to the storage unit as violation data if a storage duration of the written data is less than a write recovery time (tWR), and
• count a number of the violation data;
• and
• a memory controller configured to,
• output the write command,
• provide the associated address and the data to the cell array and the storage unit, and
• output the rewrite command to the memory device based on the number of the violation data.

A memory system, comprising:

• a memory device having a processor configured to,
• receive at least one of a write command, a rewrite command and a read command from a controller,
• determine if data stored on a memory cell and a storage unit of the memory device is unreliable, upon receiving the at least one of the write command, the rewrite command and the read command, by,
• comparing a storage duration of the data written to the storage unit with a write recovery time of the memory device;
• and
• determining the written data to be unreliable data if the storing duration is less than the write recovery time, and
• output the data from the storage unit based on the received at least one of the write command, the rewrite command and the read command and upon determining that the data is unreliable.