K4J55323QF-GC Datasheet, PDF (31/49 Pages) Samsung semiconductor – 256Mbit GDDR3 SDRAM

K4J55323QF-GC
256M GDDR3 SDRAM
WRITEs
WRITE bursts are initiated with a WRITE command, as shown in Figure.
The starting column and bank addresses are provided with the WRITE
command, and auto precharge is either enabled or disabled for that
access. If auto precharge is enabled, the row being accessed is pre-
charged at the completion of the burst. For the generic WRITE commands
used in the following illustrations, auto precharge is disabled.
During WRITE bursts, the first valid data-in element will be registered in a
rising edge of WDQS following the WRITE latency set in the mode register
and subsequent data elements will be registered on successive edges of
WDQS. Prior to the first valid WDQS edge a half cycle is needed and spec-
ified as the WRITE Preamble; the half cycle in WDQS following the last
data-in element is known as the write postamble.
/CK
CK
CKE
/CS
/RAS
/CAS
HIGH
The time between the WRITE command and the first valid falling edge of
WDQS (t_DQSS) is specified with a relative to the write latency. All of the
WRITE diagrams show the nominal case, and where the two extreme
cases (i.e., t_DQSS(min) and t_DQSS(max)) might not be intuitive, they have also
been included. Write Burst figure shows the nominal case and the
extremes of tDQSS for a burst of 4. Upon completion of a burst, assuming
no other commands have been initiated, the DQs will remain High-Z and
any additional input data will be ignored. Data for any WRITE burst may not
be truncated with a subsequent WRITE command. The new WRITE com-
mand can be issued on any positive edge of clock following the previous
WRITE command after the burst has completed. The new WRITE com-
mand should be issued x cycles after the first WRITE command should be
equals the number of desired nibbles (nibbles are required by 4n-prefetch
architecture).
/WE
A0-A7, A9
A10, A11
A8
BA0,1
CA
EN AP
DIS AP
BA
An example of nonconsecutive WRITEs is shown in Nonconsecutive
WRITE to READ figure. Full-speed random write accesses within a page or
pages can be performed as shown in Random WRITE cycles figure. Data
for any WRITE burst may be followed by a subsequent READ command.
Data for any WRITE burst may be followed by a subsequent PRE-
CHARGE command. To follow a WRITE the WRITE burst, t_WR should be
met as shown in WRITE to PRECHARGE figure.
Data for any WRITE burst can not be truncated by a subsequent PRE-
CHARGE command.
CA = Column Address
BA = Bank Address
EN AP = Enable Auto Precharge
DIS AP = Disable Auto Precharge
DON’T CARE
WRITE Command
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Rev 1.8 (Apr. 2005)