9. Burst Write Operation
The Burst Write command is issued by having CS, CAS, and WE low while holding RAS high at the rising edge of the clock. The address inputs determine the starting column address. The memory controller is required to provide an input data strobe (DQS) to the DDR SDRAM to strobe or latch the input data (DQ) and data mask (DM) into the device. During Write cycles, the data strobe applied to the DDR SDRAM is required to be nominally centered within the data (DQ) and data mask (DM) valid windows. The data strobe must be driven high nominally one clock after the write command has been registered. Timing parameters tDQSS(min) and tDQSS(max) define the allowable window when the data strobe must be driven high. Input data for the first Burst Write cycle must be applied one clock cycle after the Write command is registered into the device (WL=1). The input data valid window is nominally centered around the midpoint of the data strobe signal. The data window is defined by DQ to DQS setup time (tQDQSS) and DQ to DQS hold time (tQDQSH). All data inputs must be supplied on each rising and falling edge of the data strobe until the burst length is completed. When the burst has finished, any additional data supplied to the DQ pins will be ignored.
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