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AS4C32M32MD1
Operation at Burst Write
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During a write burst, control of the data strobe is driven by the memory controller. The LDQS, UDQS signals are centered with respect
to data and data mask. The tolerance of the data and data mask edges versus the data strobe edges during writes are specified by the
setup and hold time parameters of data (t
same cycle when the corresponding LDM, UDM signal is high (i.e. the LDM,UDM mask to write latency is zero.)
& t
) and data mask (t ). The input data is masked in the
& t
QDQSS QDQSH
DMDQSS DMDQSH
LDQS, UDQS, LDM, and UDM Timing at Write
VIH
VTT
VIL
LDQS,
UDQS
tDMDQSS
tDMDQSS
VIH
VTT
VIL
LDM,
UDM
tDMDQSH
tDMDQSH
tQDQSH
tQDQSH
VIH
VTT
VIL
Q
+3
Q
Q+1
Q+2
tQDQSS
Q+4
DQx
tQDQSS
Input Data masked
Prior to a burst of write data, given that the controller is not currently in burst write mode, the data strobe signal LDQS, UDQS changes
from Hi-Z to a valid logic low. This is referred to as the data strobe Write Preamble. Once the burst of write data is concluded, given no
subsequent burst write operation is initiated, the data strobe signal LDQS,UDQS transits from a valid logic low to Hi-Z. This is referred
the data strobe Write Postamble, t
write latency). This is different than the single data rate SDRAM where data is written in the same cycle as the Write command is issued.
. For mobile DRR data is written with a delay which is defined by the parameter t
WPST
DQSS,
DQS Pre/Postamble at Write
VIH
CLK,
/CLK
VIL
WR
tDQSS
tWPST
tWPREH
VIH
VTT
VIL
LDQS,
UDQS
"Preamble"
tWPRES
"Postamble"
VIH
VTT
VIL
Q
Q+1
Q+2
Q+3
DQx
Confidential
-11-
Rev.1.0 Sep.2014
ALSC [ ALLIANCE SEMICONDUCTOR CORPORATION ]
