K4D553238F Datasheet, PDF (14/17 Pages) Samsung semiconductor – 256Mbit GDDR SDRAM

K4D553238F-GC
256M GDDR SDRAM
Note 1 :
- The JEDEC DDR specification currently defines the output data valid window(tDV) as the time period when the data
strobe and all data associated with that data strobe are coincidentally valid.
- The previously used definition of tDV(=0.35tCK) artificially penalizes system timing budgets by assuming the worst case
output vaild window even then the clock duty cycle applied to the device is better than 45/55%
- A new AC timing term, tQH which stands for data output hold time from DQS is difined to account for clock duty cycle
variation and replaces tDV
- tQHmin = tHP-X where
. tHP=Minimum half clock period for any given cycle and is defined by clock high or clock low time(tCH,tCL)
. X=A frequency dependent timing allowance account for tDQSQmax
tQH Timing (CL4, BL2)
tHP
0
1
2
3
4
5
CK, CK
CS
DQS
DQ
tDQSQ(max)
tQH
tDQSQ(max)
Qa0
Qa1
COMMAND _READA
Power Down Timing
CK, CK
CKE
Command
t_IS
VALID
t_IS
NOP
NOP
NOP
NOP
3t_CK
NOP
NOP
VALID
Enter Power Down mode
(Read or Write operation
must not be in progress)
Exit Powr Down mode
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Rev 1.3 (Mar. 2005)