SEMICONDUCTOR MEMORY DEVICE AND REFRESH CONTROL METHOD OF MEMORY SYSTEM

There are provided a semiconductor memory device and others having a preferable operation efficiency and eliminating complicated control when refreshing a memory array divided into a plurality of banks. The semiconductor memory device includes a memory array (10) divided into a plurality of banks (0 to 3) each of which can be controlled independently and its peripheral circuit. Each of the banks 0 to 3 has a refresh counter (24) for generating a row address to be refreshed. A control circuit (20) executes refresh operation for the bank selected according to the bank selection data in accordance with a refresh request having bank selection data for selecting a plurality of banks 0 to 3 in an arbitrary combination. On the other hand, the control circuit (3) performs control no to execute refresh operation for the bank not selected according to the bank selection data. By performing such a refresh control, it is possible to rapidly perform each refresh operation by eliminating refresh of a bank in a busy state, there by improving the operation efficiency.