Datasheet

AS4C16M32MD1
Confidential 27 Rev. 1.0/July 2014
7.5.1 Read to Read
Data from a read burst may be concatenated or truncated by a subsequent READ command. The first data
from the new burst follows either the last element of a completed burst or the last desired element of a longer
burst that is being truncated. The new READ command should be issued X cycles after the first READ
command, where X equals the number of desired data-out element pairs (pairs are required by the 2n prefetch
architecture). This is shown in Figure 15.
A READ command can be initiated on any clock cycle following a previous READ command. Non-consecutive
Reads are shown in Figure 16.
Full-speed random read accesses within a page or pages can be performed as shown in Figure 17.
7.5.2 Read Burst Terminate
Data from any READ burst may be truncated with a BURST TERMINATE command, as shown in Figure 18.
The BURST TERMINATE latency is equal to the read (CAS) latency, i.e., the BURST TERMINATE command
should be issued X cycles after the READ command where X equals the desired data-out element pairs.
7.5.3 Read to Write
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 Figure 19 for the case of
nominal tDQSS .
7.5.4 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 Figure 20. 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 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.