CONFIDENTIAL
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DO NOT COPY Page 7-35
File No. SG-0204
Read Command
Writes
Write bursts are initiated with a Write command, as shown in timing figure Write Command on
following: The starting column and bank addresses are provided with the Write command, and Auto
Precharge is either enabled or disabled for that access. If Auto Precharge is enabled, the row being
accessed is precharged at the completion of the burst. For the generic Write commands used in the
following illustrations, Auto Precharge is disabled.
During Write bursts, the first valid data-in element is registered on the first rising edge of DQS
following the write command, and subsequent data elements are registered on successive edges of
DQS. The Low state on DQS between the Write command and the first rising edge is known as the
write preamble; the Low state on DQS following the last data-in element is known as the write
postamble. The time between the Write command and the first corresponding rising edge of DQS
(tDQSS) is specified with a relatively wide range (from 75% to 125% of one clock cycle), so most of
the Write diagrams that follow are drawn for the two extreme cases (i.e. tDQSS(min) and
tDQSS(max)). Timing figure Write Burst (Burst Length = 4) on page 33 shows the two extremes of
tDQSS for a burst of four. Upon completion of a burst, assuming no other commands have been
initiated, the DQs and DQS enters High-Z and any additional input data is ignored.Data for any Write
burst may be concatenated with or truncated with a subsequent Write command. In either case, a
continuous flow of input data can be maintained.
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