K4D263238D Datasheet, PDF (14/18 Pages) Samsung semiconductor – 1M x 32Bit x 4 Banks Double Data Rate Synchronous DRAM with Bi-directional Data Strobe and DLL

K4D263238D
128M DDR 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 valid 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 defined 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 (CL3, BL2)
0
1
CK, CK
CS
DQS
DQ
tHP
2
3
4
5
tDQSQ(max)
tQH
tDQSQ(max)
Da0
Da1
COMMAND
READA
- 14 -
Rev. 1.3 (Jul. 2002)