K4C561638C-TCD4000 Datasheet, PDF (34/42 Pages) Samsung semiconductor – 256Mb Network-DRAM

K4C5608/1638C
256Mb Network-DRAM
Auto-Refresh Timing (CL=3, BL=4)
0
1
2
3
4
5
6
7
CK
CK
I_RC = 5 cycles
Command
RDA LAL
I_RCD = 1 cycle
DESL
I_RAS = 4 cycles
WRA REF
I_RCD = 1 cycle
8
9
10
11
I_REFC = 15 cycles
DESL
RDA
or
WRA
LAL or
MRS or
REF
DQS
Hi-Z
(Output)
DQ
Hi-Z
(Output)
CL = 3
Hi-Z
Q0 Q1 Q2 Q3 ^Hi-Z
Note : In case of CL=3, I_REFC must be meet 15 clock cycles. When the Auto-Refresh operation is performed,
the synthetic average interval of Auto-Refresh command specified by t_REFI must be satisfied. t_REFI is
average Interval time in 8 Refresh cycles that is sampled randomly.
t₁
CK
WRA REF
t₂
WRA REF
t₃
WRA REF
t₇
t₈
WRA REF
WRA REF
8 Refresh Cycle
t_REFI = ^{Total time of 8 Refresh cycle = t1 + t2 + t3 + t4 + t5+ t6+ t 7+ t8}
8
8
t_REFI is specified to avoid partly concentrated current of Refresh operation that is activated larger area than
Read/Write operation.
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REV. 0.7 Aug. 2003