W972GG6JB Datasheet, PDF (32/87 Pages) Winbond – 16M  8 BANKS  16 BIT DDR2 SDRAM

W972GG6JB
8.2 Clock Enable (CKE) Truth Table for Synchronous Transitions
CURRENT
STATE²
CKE
Previous Cycle ¹ Current Cycle ¹
(N-1)
(N)
COMMAND (N) ³
RAS , CAS , WE , CS
ACTION (N) ³
L
Power Down
L
L
X
Maintain Power Down
H
DESELECT or NOP
Power Down Exit
NOTES
11, 13, 15
4, 8, 11, 13
L
Self Refresh
L
Bank(s) Active
H
H
All Banks Idle
H
L
X
Maintain Power Down
11, 15, 16
H
DESELECT or NOP
Self Refresh Exit
4, 5, 9, 16
L
DESELECT or NOP
Active Power Down
Entry
4, 8, 10, 11,
13
L
DESELECT or NOP
Precharge Power Down 4, 8, 10, 11,
Entry
13
L
REFRESH
Self Refresh Entry
6, 9, 11, 13
H
H
Refer to the Command Truth Table
7
Notes:
1. CKE (N) is the logic state of CKE at clock edge N; CKE (N–1) was the state of CKE at the previous clock edge.
2. Current state is the state of the DDR2 SDRAM immediately prior to clock edge N.
3. COMMAND (N) is the command registered at clock edge N, and ACTION (N) is a result of COMMAND (N).
4. All states and sequences not shown are illegal or reserved unless explicitly described elsewhere in this document.
5. On Self Refresh Exit DESELECT or NOP commands must be issued on every clock edge occurring during the tXSNR period.
Read commands may be issued only after tXSRD (200 clocks) is satisfied.
6. Self Refresh mode can only be entered from the All Banks Idle state.
7. Must be a legal command as defined in the Command Truth Table.
8. Valid commands for Power Down Entry and Exit are NOP and DESELECT only.
9. Valid commands for Self Refresh Exit are NOP and DESELECT only.
10. Power Down and Self Refresh can not be entered while Read or Write operations, (Extended) Mode Register Set
operations or Precharge operations are in progress. See section 7.9 "Power Down Mode" and section 7.3.7/7.3.8 "Self
Refresh Entry/Exit Command" for a detailed list of restrictions.
11. tCKEmin of 3 clocks means CKE must be registered on three consecutive positive clock edges. CKE must remain at the
valid input level the entire time it takes to achieve the 3 clocks of registration. Thus, after any CKE transition, CKE may not
transition from its valid level during the time period of tIS + 2 x tCK + tIH.
12. The state of ODT does not affect the states described in this table. The ODT function is not available during Self Refresh.
See section 7.2.4.
13. The Power Down does not perform any refresh operations. The duration of Power Down Mode is therefore limited by the
refresh requirements outlined in section 7.9.
14. CKE must be maintained HIGH while the SDRAM is in OCD calibration mode.
15. “X” means “don‟t care (including floating around VREF)” in Self Refresh and Power Down. However ODT must be driven
high or low in Power Down if the ODT function is enabled (Bit A2 or A6 set to “1” in EMR (1)).
16. VREF must be maintained during Self Refresh operation.
8.3 Data Mask (DM) Truth Table
FUNCTION
DM
DQS
NOTE
Write enable
L
Valid
1
Write inhibit
H
X
1
Note:
1. Used to mask write data, provided coincident with the corresponding data.
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Publication Release Date: Nov. 29, 2011
Revision A02