M14D5121632A_1 Datasheet, PDF (45/59 Pages) Elite Semiconductor Memory Technology Inc. – 8M x 16 Bit x 4 Banks DDR II SDRAM

ESMT
M14D5121632A
Operation Temperature Condition (TC) -40°C~95°C
Read with Auto Precharge
If A10 is HIGH when a Read command is issued, the Read with Auto Precharge function is engaged. The device starts an Auto
Precharge operation on the rising edge which is (AL + BL/2) cycles later than the Read with AP command if t_RAS (min) and t_RTP(min)
are satisfied.
If t_RAS(min) is not satisfied at the edge, the start point of Auto Precharge operation will be delayed until t_RAS(min) is satisfied.
If t_RTP (min) is not satisfied at the edge, the start point of Auto Precharge operation will be delayed until t_RTP (min) is satisfied.
In case the internal precharge is pushed out by t_RTP, t_RP starts at the point where the internal precharge happens (not at the next
rising clock edge after this event). So for BL = 4, the minimum time from Read_AP to the next Bank Active command becomes AL +
(t_RTP + t_RP)*. For BL = 8, the time from Read_AP to the next Bank Active command is AL + 2 + (t_RTP + t_RP)*. (Note: “*” means
“rouded up to the next integer”).
< RL= 4 (AL= 1; CL= 3) >
T0
T1
T2
T3
T4
T5
T6
T7
T8
CLK
CLK
BL = 8
t RTP <= 2 clocks
CMD
Posted CAS
READ A
Autoprecharge
DQS,DQS
NOP
NOP
AL+BL/2 clks
NOP
NOP
NOP
NOP
> = tRP
NOP
Bank A
Active
DQs
AL = 1
CL = 3
RL = 4
DoutA0 DoutA1 DoutA2 DoutA3 DoutA4 DoutA5 DoutA6 DoutA7
>= tRTP
tRTP
Precharge begins here
BL = 4
t RTP > 2 clocks
CMD
Posted CAS
READ A
Autoprecharge
NOP
NOP
>=AL+tRTP+tRP
NOP
DQS,DQS
AL = 1
CL = 3
RL = 4
DQs
tRTP
NOP
NOP
NOP
DoutA0 DoutA1 DoutA2 DoutA3
tRP
Precharge begins here
Bank A
Active
NOP
A new Bank Active command may be issued to the same bank if the following two conditions are satisfied simultaneously.
(1) The Precharge time (t_RP) has been satisfied from the clock at which the Auto Precharge begins.
(2) The RAS cycle time (t_RC) from the previous bank activation has been satisfied.
Elite Semiconductor Memory Technology Inc.
Publication Date : Feb. 2009
Revision : 1.1
45/59