W949D6CB Datasheet, PDF (32/60 Pages) Winbond – 512Mb Mobile LPDDR

W949D6CB / W949D2CB
7.5.9 Read to Write
512Mb Mobile LPDDR
Data from READ burst must be completed or truncated before a subsequent WRITE command can be issued. If
truncation is necessary, the BURST TERMINATE command must be used, as shown in following figure for the case
of nominal tDQSS
CK
CK
Command
READ
BST
NOP
WRITE
NOP
NOP
Address
BA,Col n
DQS
CL=2
BA,Col b
tDQSS
DQ
DO n
DM
Command
Address
READ
BA,Col n
DQS
DQ
BST
CL=3
NOP
NOP
WRITE
BA,Col b
NOP
DO n
DM
1) DO n = Data Out from column n; DI b= Data In to column b
= Don't Care
2) Burst length = 4, 8 or 16 in the cases shown; If the burst length is 2, the BST command can be omitted
3) Shown with nominal tAC, tDQSCK and tDQSQ
7.5.10 Read to Pre-charge
A Read burst may be followed by or truncated with a PRECHARGE command to the same bank (provided Auto Pre-
charge 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 pre-charge 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 Pre-charge 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.
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Publication Release Date: Sep, 21, 2011
Revision A01-007