K7R643682M SAMSUNG [Samsung semiconductor], K7R643682M Datasheet - Page 8

• Manufacturer Part Number: K7R643682M
• Description: 2Mx36 & 4Mx18 & 8Mx9 QDRTM II b2 SRAM
• Manufacturer: SAMSUNG [Samsung semiconductor]

QDRII SRAMs must be powered up and initialized in a predefined manner to prevent undefined operations.
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* Notes: When the operating frequency is changed, DLL reset should be required again.
Detail Specification of Power-Up Sequence in QDRII SRAM
Power up & Initialization Sequence (Doff pin Fixed high, Clock controlled)
Status
Power up & Initialization Sequence (Doff pin controlled)
K7R643682M
K7R641882M
K7R640982M
Status
Power-Up Sequence
DLL Constraints
V
V
K,K
V
V
REF
K,K
DDQ
V
V
Doff
DD
DDQ
REF
DD
1. DLL uses either K or C clock as its synchronizing input, the input should have low phase jitter which is specified as TKC var.
After DLL reset again, the minimum 1024 cycles of clock input is needed to lock the DLL.
1. Apply power and keep Doff at low state (All other inputs may be undefined)
2. Just after the stable power and clock(K,K, C, C), take Doff to be high.
3. The additional 1024cycles of clock input is required to lock the DLL after enabling DLL
2. The lower end of the frequency at which the DLL can operate is 120MHz.
3. If the incoming clock is unstable and the DLL is enabled, then the DLL may lock onto a wrong frequency
* Notes: If you want to tie up the Doff pin to High with unstable clock, then you must stop the clock for a few seconds
(Min. 30ns) to reset the DLL after it become a stable clock status.
and this may cause the failure in the initial stage.
- Apply VDD before VDDQ
- Apply VDDQ before VREF or the same time with VREF
Power-Up
Power-Up
Unstable
CLKstage
Unstable
CLKstage
2Mx36 & 4Mx18 & 8Mx9 QDR
- 8 -
Stop Clock
Min 30ns
must be stable
Inputs Clock
DLL Locking Range
must be stable
Inputs Clock
1024 cycle
DLL Locking Range
1024 cycle
TM
Preliminary
II b2 SRAM
Any
Command
Any
Command
Oct. 2004
Rev 0.5