K4N26323AE Datasheet, PDF (20/52 Pages) Samsung semiconductor – 128Mbit GDDR2 SDRAM

K4N26323AE-GC
128M GDDR2 SDRAM
Precharge Command
The Precharge Command is used to precharge or close a bank that has been activated. The Precharge Command is
triggered when CS, RAS and WE are low and CAS is high at the rising edge of the clock. The Precharge Command can
be used to precharge each bank independently or all banks simultaneously. Three address bits A8, BA0 and BA1 are
used to define which bank to precharge when the command is issued.
Bank Selection for Precharge by Address Bits
A8
LOW
LOW
LOW
LOW
HIGH
BA1
LOW
LOW
HIGH
HIGH
DON’T CARE
BA0
LOW
HIGH
LOW
HIGH
DON’T CARE
Precharged Bank(s)
Bank 0 only
Bank 1 only
Bank 2 only
Bank 3 only
All Banks 0 ~ 3
Burst Read Operation Followed by Precharge
For the earliest possible precharge, the precharge command may be issued on the rising edge which is CAS latency
(CL) clock cycles before the end of the read burst. A new bank active (command) may be issued to the same bank after
the RAS precharge time (t_RP). A precharge command cannot be issued until t_RAS is satisfied.
Burst Read Operation Followed by Precharge: RL = 7 (AL=0, CL=7), t_RP= 8
0
CK, CK
2
3
4
5
6
7
8
9
10
11
CMD
Post CAS
READ A
Precharge
NOP
NOP
NOP
NOP
NOP
NOP
NOP
Bank A
Active
NOP
DQS
DQ
CL =7
> = t_RP
DOUTA₀ DOUTA₁ DOUTA₂ DOUTA₃
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Rev. 1.7 (Jan. 2003)