Method and apparatus for controlling column select lines in a

Abstract

A column select line control circuit for a synchronous semiconductor memory device increases the time margin for writing input data to memory cells in prefetch mode by delaying the disablement of the column select lines during a write operation, thereby extending the time for writing data to the cells. The control circuit includes a column select line control circuit that generates enable and disable signals in response to an internal clock signal, and a column decoder that enables and disables a column select line in response to the enable and disable signals. In pipeline mode, the column select line control circuit generates the disable signal by delaying the internal clock signal and generates the enable signal by delaying and inverting the internal clock signal. In prefetch mode, the column select line control signal adds an additional delay to both the enable and disable signals, but only during write operations.