IBM0625164GT3B IBM0625404GT3B
IBM06254B4GT3B IBM0625804GT3B
Advance
256Mb Double Data Rate Synchronous DRAM
Truth Table 2: Clock Enable (CKE)
1. CKEn 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 DDR 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.
CKE n-1
CKEn
Current State
Command n
Action n
Notes
1
Previous Current
Cycle
Cycle
Self Refresh
Self Refresh
Power Down
Power Down
All Banks Idle
All Banks Idle
Bank(s) Active
L
L
L
H
L
X
Maintain Self-Refresh
Deselect or NOP
X
Exit Self-Refresh
L
Maintain Power-Down
Exit Power-Down
L
H
L
Deselect or NOP
Deselect or NOP
AUTO REFRESH
Deselect or NOP
H
H
H
Precharge Power-Down Entry
Self Refresh Entry
L
L
Active Power-Down Entry
See “Truth Table 3: Current State
Bank n - Command to Bank n
(Same Bank)” on page 46
H
H
1. Deselect or NOP commands should be issued on any clock edges occurring during the Self Refresh Exit (t
) period. A mini-
XSNR
mum of 200 clock cycles are needed before applying a read command to allow the DLL to lock to the input clock.
©IBM Corporation. All rights reserved.
Use is further subject to the provisions at the end of this document.
29L0011.E36997
10/99
Page 45 of 75
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