EMD12324P Emlsi Inc., EMD12324P Datasheet - Page 22

• Manufacturer Part Number: EMD12324P
• Description: 512m 16m X 32 Mobile Ddr Sdram
• Manufacturer: Emlsi Inc.

READs
READ bursts are initiated with a READ command.
The starting column and bank addresses are provided with the READ command and auto precharge is either enabled
or disabled for that burst access. If auto precharge is enabled, the row being accessed is precharged at the completion
of the burst. For the READ commands used in the following illustrations, auto precharge is disabled.
During READ bursts, the valid data-out element from the starting column address will be available following the CAS
latency after the READ command. Each subsequent data-out element will be valid nominally at the next positive or
negative clock edge (i.e., at the next crossing of CK and CKB). DQS is driven by the Mobile DDR SDRAM along with
output data. The initial LOW state on DQS is known as the read preamble; the LOW state coincident with the last data-
out element is known as the read postamble.
Upon completion of a burst, assuming no other commands have been initiated, the DQs will go High-Z.
Data from any READ burst may be concatenated with or truncated with data from a subsequent READ command. In
either case, a continuous flow of data can be maintained. The first data element from the new burst follows either the
last element of a completed burst or the last desired data element of a longer burst which 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
element pairs (pairs are required by the 2n-prefetch architecture).
A READ command can be initiated on any clock cycle following a previous READ command.
CL2
CL3
Command
Burst Read Operation < Burst Length=4, CAS Latency=2, 3) >
DQ’s
DQ’s
DQS
DQS
CK
CKB
READ
0
NOP
t
RPRE
1
Dout 0 Dout 1 Dout 2 Dout 3
NOP
t
RPRE
2
Dout 0 Dout 1 Dout 2 Dout 3
NOP
3
t
RPST
22
NOP
4
NOP
512M: 16M x 32 Mobile DDR SDRAM
5
NOP
6
EMD12324P
NOP
Preliminary
7
NOP
Rev 0.0
8