HM5216165 Series
CKE Truth Table
CKE
n-1
H
L
L
REF
SELF
H
H
H
H
SELFX
L
L
L
L
CS
H
×
×
L
L
L
H
L
H
L
H
RAS
×
×
×
L
L
H
×
H
×
H
×
CAS
×
×
×
L
L
H
×
H
×
H
×
WE
×
×
×
H
H
H
×
H
×
H
×
Current state
Active
Any
Function
n
L
L
H
H
L
L
L
H
H
H
H
Address
×
×
×
×
×
×
×
×
×
×
×
EO
Clock suspend
Idle
Idle
Idle
Self-refresh
Power down
8
Clock suspend mode entry
Clock suspend
Clock suspend mode exit
Auto refresh command
Self refresh entry
Power down entry
Note: H: V
IH
. L: V
IL
.
×:
V
IH
or V
IL
.
Clock suspend mode entry:
The synchronous DRAM enters clock suspend mode from active mode by
setting CKE to Low. The clock suspend mode changes depending on the current status (1 clock before) as
shown below.
ACTIVE clock suspend:
This suspend mode ignores inputs after the next clock by internally maintaining
the bank active status.
READ suspend and READ A suspend:
The data being output is held (and continues to be output).
WRITE suspend and WRIT A suspend:
In this mode, external signals are not accepted. However, the
internal state is held.
Clock suspend:
During clock suspend mode, keep the CKE to Low.
Clock suspend mode exit:
The synchronous DRAM exits from clock suspend mode by setting CKE to High
during the clock suspend state.
IDLE:
In this state, all banks are not selected, and completed precharge operation.
Auto refresh command [REF]:
When this command is input from the IDLE state, the synchronous DRAM
starts auto refresh operation. (The auto refresh is the same as the CBR refresh of conventional DRAMs.)
During the auto refresh operation, refresh address and bank select address are generated inside the
synchronous DRAM. For every auto refresh cycle, the internal address counter is updated. Accordingly,
4096 times are required to refresh the entire memory. Before executing the auto refresh command, all the
banks must be in the IDLE state. In addition, since the precharge for all banks is automatically performed
after auto refresh, no precharge command is required after auto refresh.
L
Self refresh exit
Power down exit
Pr
Data Sheet E0167H10
od
uc
t
ELPIDA [ ELPIDA MEMORY ]
