REFRESH CONTROL CIRCUIT

PURPOSE:To prevent the increase of current consumption due to unnecessary refresh operation by providing a refresh control circuit which performs the refresh operation of memory banks other than a memory bank set as a VRAM area simultaneously with access for display and varying the period of the refresh operation. CONSTITUTION:Four memory banks 10 to 13 consisting of RAMs requiring refresh, the VRAM area as which one memory bank is set, and a refresh control circuit 1 which performs the refresh operation of memory banks other than the memory bank set as the VRAM area simultaneously with access for display are provided. The period of the refresh operation of the refresh control circuit 1 is varied. That is, the refresh period of memory banks other than the memory bank set as the VRAM area is varied to refresh the memory with a period different from that of the access for display. Thus, the increase of current consumption due to unnecessary refresh operation of the memory is prevented.