eorex
EM428M1644RTA
4. Command Truth Table for CKE
CKE
n-1
Current State
/CS /R /C /W
Addr.
Action
n
X
H
H
H
H
H
L
H
L
L
L
L
L
L
H
L
L
L
L
L
L
H
H
X
H
L
X
X
H
H
H
L
X
X
H
H
L
X
X
H
L
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
INVALID
Exist Self-Refresh
Exist Self-Refresh
ILLEGAL
Self Refresh
L
L
X
X
X
X
X
H
L
ILLEGAL
ILLEGAL
L
X
X
X
X
H
H
L
X
X
H
L
X
X
X
H
H
H
L
NOP(Maintain self refresh)
INVALID
Exist Power down
Exist Power down
ILLEGAL
X
H
H
H
H
H
L
Both bank
precharge
power down
L
L
X
X
X
X
X
ILLEGAL
ILLEGAL
L
X
X
X
X
X
X
H
X
X
X
NOP(Maintain Power down)
Refer to function true table
H
L
(Note 3)
Enter power down mode
(Note 3)
H
H
H
H
H
H
L
L
L
L
L
L
L
L
L
L
L
H
H
H
L
H
H
L
H
L
X
X
Enter power down mode
ILLEGAL
ILLEGAL
X
H
H
L
X
All Banks
Idle
H
L
RA
X
Row active/Bank active
(Note 3)
Enter self-refresh
L
L
L
L
L
Op-Code Mode register access
Op-Code Special mode register access
H
L
L
L
L
L
X
H
X
X
X
X
X
X
Refer to current state
Any State Other
than Listed above
H
X
X
X
X
Refer to command truth table
Remark: H = High level, L = Low level, X = High or Low level (Don't care)
Notes 1: After CKE’s low to high transition to exist self refresh mode.And a time of tRC(min) has to be
Elapse after CKE’s low to high transition to issue a new command.
Notes 2:CKE low to high transition is asynchronous as if restarts internal clock.
Notes 3:Power down and self refresh can be entered only from the idle state of all banks.
Apr. 2007
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