Dynamic random access memory device capable of programming a refresh period and a bit organization

摘要

A dynamic random access memory device includes a mode register set, a refresh period selector, and a bit organization selector. The mode register set outputs decoded signals having values according to a user-stored value in the mode register set. The mode register set can be accessed in response to an address externally supplied when a mode set command is applied. The refresh period selector generates a plurality of refresh period select signals in response to the decoded signals. A refresh counter in the device generates a sequence of row addresses having a timing according to a refresh period determined from an activated refresh period select signal. The bit organization select circuit generates a plurality of bit organization select signals in response to the decoded signals from the mode register set. A data output multiplexer in the device selects some of the read data bits according to a bit organization determined by one of the bit organization select signals.