US Patent 7821846 Semiconductor memory device and its driving method

A semiconductor memory device including a first latch that latches a Mode Register Set (MRS) code consisting of multiple bits in response to an MRS command pulse, a code controller that generates a control signal in response to a code value of preset bits out of an output signal from the first latch, a second latch that selectively latches the output signal from the first latch in response to the control signal and a mode decoder that decodes an output signal from the second latch to output an operation mode.