ESMT
M13S2561616A (2A)
Operation Temperature Condition -40°C~85°C
Auto Refresh & Self Refresh
Auto Refresh
An auto refresh command is issued by having CS , RAS and CAS held low with CKE and WE high at the rising edge of
the clock (CLK). All banks must be precharged and idle for tRP(min) before the auto refresh command is applied. No control of
the external address pins is requires once this cycle has started because of the internal address counter. When the refresh
cycle has completed, all banks will be in the idle state. A delay between the auto refresh command and the next activate
command or subsequent auto refresh command must be greater than or equal to the tRFC(min).
A maximum of eight consecutive AUTO REFRESH commands (with tRFC(min)) can be posted to any given DDR SDRAM
meaning that the maximum absolute interval between any AUTO REFRESH command and the next AUTO REFRESH
command is 8 x tREFI
.
C L K
C L K
Auto
Refresh
C O MM A N D
P R E
C M D
C K E
= H i g h
t
R F C
t
R P
Self Refresh
A self refresh command is defines by having CS , RAS , CAS and CKE held low with WE high at the rising edge of the
clock (CLK). Once the self refresh command is initiated, CKE must be held low to keep the device in self refresh mode. During
the self refresh operation, all inputs except CKE are ignored. Since CKE is an SSTL_2 input, VREF must be maintained during
self refresh. The clock is internally disabled during self refresh operation to reduce power consumption. The self refresh is exited
by supplying stable clock input before returning CKE high, asserting deselect or NOP command and then asserting CKE high
for longer than tXSRD for locking of DLL.
C L K
C L K
Self
Refresh
Auto
Refresh
NOP
NO P
N OP
C O MM A N D
NO P
N OP
NO P
t
X S N R ( m i n )
C K E
t
I S
t
I S
Note: After self refresh exit, input an auto refresh command immediately.
Elite Semiconductor Memory Technology Inc.
Publication Date : Sep. 2012
Revision : 1.1 27/49
ESMT [ ELITE SEMICONDUCTOR MEMORY TECHNOLOGY INC. ]
