K4N26323AE Datasheet, PDF (23/52 Pages) Samsung semiconductor – 128Mbit GDDR2 SDRAM

K4N26323AE-GC
128M GDDR2 SDRAM
Burst Read with Auto Precharge
If A8 is high when a Read Command is issued, the Read with Auto-Precharge function is engaged. The GDDR2
SDRAM starts an Auto Precharge operation on the rising edge which is (AL + BL/2)cycles later from the read with Auto
Precharge command, when tRAS(min) is satisfied. If tRAS(min) is not satisfied at the edge, the start point of Auto Pre-
charge operation will be delayed until tRAS(min) is satisfied. A new bank active command may be issued to the same
bank if the following two conditions are satisfied simultaneously.
(1) The RAS precharge time (tRP) has been satisfied from the clock at which the auto precharge begins.
(2) The RAS cycle time (tRC) from the previous bank activation has been satisfied.
When the Read with Auto-Precharge command is issued, new command (Read, Read with Auto Precharge or pre-
charge) of same bank can be asserted tCCD=2 clock cycles later.
Burst Read with Auto Precharge Followed by Same Bank Activation :
RL = 8 (AL = 1, CL = 7, internal t_RP = 8)
0
3
7
8
9
10
11
12
CK, CK
CMD
A8 = 1
Post CAS
READ A
NOP
NOP
NOP
NOP
NOP
NOP
NOP
Bank A
Activate
NOP
DQS
DQ’s
Auto Precharge Begins
RL = 8
> = t_RP
DOUTA₀ DOUTA₁ DOUTA₂ DOUTA₃
Burst Read with Auto Precharge (AL=0)
Asserted
command
READ
READ with Auto Precharge
Active
Precharge
1
Illegal
Illegal
Illegal
Illegal
For same bank
2
3
Legal
Illegal
Legal
Illegal
Illegal
Illegal
Legal
Illegal
4
Illegal
Illegal
Illegal
Illegal
1
Illegal
Illegal
Legal
Legal
For different bank
2
3
Legal
Legal
Legal
Legal
Legal
Legal
Legal
Legal
4
Legal
Legal
Legal
Legal
*When AL(Additive Latency) is 1, a precharge command for same bank can be issued at 3th cycle only and others are same with
AL=0.
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Rev. 1.7 (Jan. 2003)