EM42AM1684RTC
4. Command Truth Table for CKE
CKE
Current State
/CS /R /C /W
Addr.
Action
n-1
H
L
L
L
L
L
L
n
X
H
H
H
H
H
L
X
H
L
L
L
X
X
H
H
H
L
X
X
X
H
H
H
L
X
X
H
H
L
X
X
X
X
H
H
L
X
X
H
L
X
X
X
X
X
H
L
X
X
X
X
X
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
ILLEGAL
ILLEGAL
L
X
X
H
L
L
L
NOP(Maintain self refresh)
INVALID
Exist Power down
Exist Power down
ILLEGAL
H
L
L
L
L
X
H
H
H
H
H
L
Both bank
precharge
power down
ILLEGAL
ILLEGAL
L
L
L
X
X
X
X
X
X
H
X
X
X
NOP(Maintain Power down)
Refer to function true table
H
H
Enter power down mode(Note 3)
H
L
L
Enter power down mode(Note 3)
ILLEGAL
H
H
H
H
H
H
L
L
L
L
L
L
H
H
H
L
H
H
L
H
L
H
L
X
H
H
L
X
X
X
RA
X
L
L
L
L
ILLEGAL
All Banks
Idle
Row active/Bank active
Enter self-refresh(Note 3)
L
L
L
L
L
Op-Code Mode register access
H
L
L
L
L
L
Op-Code Special mode register access
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
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.
Sep. 2010
www.eorex.com
15/21
EOREX [ EOREX CORPORATION ]
