KM44L32131BT-GY 데이터 시트보기 (PDF) - Samsung
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KM44L32131BT-GY Datasheet PDF : 49 Pages
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128Mb DDR SDRAM
Target
3.3.11 Read With Auto Precharge
If a read with auto-precharge command is initiated, the DDR SDRAM automatically enters the precharge
operation BL/2 clock later from a read with auto-precharge command when tRAS(min) is satisfied. If not, the
start point of precharge operation will be delayed until tRAS(min) is satisfied. Once the precharge operation
has started the bank cannot be reactivated and the new command can not be asserted until the precharge
time(tRP) has been satisfied.
< Burst Length=4, CAS Latency= 2, 2.5>
0
CK
CK
Command
BANK A
ACTIVE
CAS Latency=2
DQS
DQ ′s
1
2
3
NOP
READ A
Auto Precharge
tRAS(min.)
NOP
CAS Latency=2.5
DQS
DQ ′s
Begin Auto-Precharge
4
5
6
7
8
NOP
NOP
NOP
NOP
NOP
Dout 0 Dout 1 Dout 2 Dout 3
tRP
* Bank can be reactivated at the
completion of precharge
Dout 0 Dout 1 Dout 2 Dout 3
Figure 19. Read with auto precharge timing
When the Read with Auto precharge command is issued, new command can be asserted at 3,4 and 5
respectively as follows,
Asserted
command
READ
For same Bank
3
4
READ +
No AP*1
READ+
No AP
5
Illegal
For Different Bank
3
4
5
Legal
Legal
Legal
READ+AP
READ +
AP
READ +
AP
Illegal
Legal
Legal
Legal
Active
Illegal
Illegal
Illegal
Legal
Legal
Precharge
Legal
*1 : AP = Auto Precharge
Legal
Illegal
Legal
Legal
Table 6. Operating description when new command asserted
while read with auto precharge is issued
Legal
Legal
- 29 of 63 -
REV. 0.61 August 9. '99
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