HYB18M512160BFX Datasheet, PDF (26/52 Pages) Qimonda AG – DRAMs for Mobile Applications 512-Mbit DDR Mobile-RAM

HYB18M512160BFX
512-Mbit DDR Mobile-RAM
Functional Description
2.4.5.2 READ to WRITE
Data from any 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 Figure 18.
CK
CK
Command
Address
READ
BA,Col n
DQS
DQ
DM
BST
CL=2
NOP
DO n
WRITE
BA,Col b
t_DQSS
NOP
Di b
NOP
Command
Address
READ
BA,Col n
DQS
DQ
DM
BST
NOP
NOP
CL=3
DO n
WRITE
BA,Col b
DO n = Data Out from column n; DI b = Data In to column b
1 subsequent element of Data Out appear in the programmed order following DO n.
Data In elements are applied following DI b in the programmed order
Figure 18 READ to WRITE
NOP
Di b
= Don't Care
2.4.5.3 READ to PRECHARGE
A READ burst may be followed by, or truncated with a PRECHARGE command to the same bank (provided that
Auto Precharge was not activated).
The PRECHARGE command should be issued x clock cycles after the READ command, where x equals the
number of desired data element pairs. This is shown in Figure 19. Following the PRECHARGE command, a
subsequent command to the same bank cannot be issued until t_RP is met. Please note that part of the row
precharge time is hidden during the access of the last data 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 the same READ burst with Auto Precharge
enabled. The disadvantage of the PRECHARGE command is that it requires that the command and address
busses 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.
Data Sheet
26
Rev. 1.10, 2006-11
04052006-4SYQ-ZRN3