W949D6DB Datasheet, PDF (34/60 Pages) Winbond – Standard Self Refresh Mode

W949D6DB / W949D2DB
8.5.10 Read to Precharge
A Read burst may be followed by or truncated with a PRECHARGE command to the same bank
(provided Auto Precharge was not activated). The PRECHARGE command should be issued X cycles
after the READ command, where X equal the number of desired data-out element pairs. This is shown
in following figure. Following the PRECHARGE command, a subsequent command to the same bank
cannot be issued until tRP is met. Note that part of the row precharge time is hidden during the access
of the last data-out elements.
In the case of a Read being executed to completion, a PRECHARGE command issued at the optimum
time (as described above) provides the same operation that would result from Read burst with Auto
Precharge enabled. The disadvantage of the PRECHARGE command is that it requires that the
command and address buses be available at the appropriate time to issue the command. The advantage
of the PRECHARGE command is that it can be used to truncate bursts.
CK
CK
Command
Address
READ
BA,Col n
DQS
DQ
DQS
DQ
NOP
CL=2
PRE
Bank
(a or all)
NOP
NOP
t_RP
DO n
CL=3
DO n
ACT
BA,Row
= Don't Care
1) DO n = Data Out from column n
2) Cases shown are either uninterrupted of 4, or interrupted bursts of 8 or 16
3) Shown with nominal tAC,tDQSCK and tDQSQ
4) Precharge may be applied at (BL/2) tCK after the READ command.
5) Note that Precharge may not be issued before tRAS ns after the ACTIVE command for applicable banks.
6) The ACTIVE command may be applied if tRC has been met.
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Publication Release Date: Oct. 08, 2014
Revision: A01-003