ESMT
M13S5121632A (2R)
Power down
Power down is entered when CKE is registered Low (no accesses can be in progress). If power down occurs when all banks are
idle, this mode is referred to as precharge power-down; if power down occurs when there is a row active in any bank, this mode
is referred to as active power-down.
Entering power down deactivates the input and output buffers, excluding CLK, CLK and CKE. In power down mode, CKE Low
must be maintained, and all other input signals are “Don’t Care”. The minimum power down duration is at least 1 tCK + tIS.
However, power down duration is limited by the refresh requirements of the device.
The power down state is synchronously exited when CKE is registered High (along with a NOP or DESELECT command). A
valid command may be applied 1 tCK + tIS after exit from power down.
C L K
C L K
tRP
C K E
tIS
tIS
tIS
t
IS
C O M M A N D
Precharge
Active
Read
Enter Precharge
power-down
mode
Exit Precharge
power-down
mode
Enter Active
power-down
mode
Exit Active
power-down
mode
Functional Truth Table
Truth Table – CKE [Note 1~4, 6]
COMMAND n
CKE n-1
CKE n
Current State
Power Down
Self Refresh
ACTION n
NOTE
L
L
L
X
Maintain Power Down
Maintain Self Refresh
Exit Power Down
L
X
7
L
H
H
L
Power Down
Self Refresh
All Banks Idle
Bank(s) Active
All Banks Idle
NOP or DESELECT
NOP or DESELECT
NOP or DESELECT
NOP or DESELECT
AUTO REFRESH
L
Exit Self Refresh
5, 7
H
Precharge Power Down Entry
Active Power Down Entry
Self Refresh Entry
H
H
L
L
H
H
See the Truth Tables as follow
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 DDR SDRAM immediately prior to clock edge n.
3. COMMAND n is the command registered at clock edge n, and ACTION n is the result of COMMAND n.
4. All states and sequences not shown are illegal or reserved.
5. DESELECT and NOP DESELECT or NOP commands should be issued on any clock edges occurring during the tXSNR or
XSRD period. A minimum of 200 clock cycles is needed before applying any executable command, for the DLL to lock.
t
6. Operation or timing that is not specified is illegal and after such an event, in order to guarantee proper operation, the
DRAM must be powered down and then restarted through the specified initialization sequence before normal operation
can continue.
7. VREF must be maintained during Self Refresh operation.
Elite Semiconductor Memory Technology Inc.
Publication Date : Feb. 2013
Revision : 1.3 28/48
ESMT [ ELITE SEMICONDUCTOR MEMORY TECHNOLOGY INC. ]
