Data Sheet
HY[B/E]18M1G16[0/1]BF
1-Gbit DDR Mobile-RAM
FIGURE 34
Auto Refresh
CK
CK
tRP
NOP
tRFC
NOP
tRFC
NOP
Command
Address
PRE
ARF
NOP
ARF
NOP
ACT
Ba A,
Row n
Row n
A10 (AP)
DQ
Pre All
High-Z
= Don't Care
Ba A, Row n = Bank A, Row n
2.4.9.2
SELF REFRESH
The SELF REFRESH command can be used to retain data in the DDR Mobile-RAM, even if the rest of the system is powered
down. When in the Self Refresh mode, the DDR Mobile-RAM retains data without external clocking. The DDR Mobile-RAM
device has a built-in timer to accommodate Self Refresh operation. The SELF REFRESH command is initiated like an AUTO
REFRESH command except CKE is LOW. Input signals except CKE are “Don’t Care” during Self Refresh. The user may halt
the external clock one clock after Self Refresh entry is registered.
Once the command is registered, CKE must be held low to
keep the device in Self Refresh mode. The device executes a
minimum of one AUTO REFRESH command internally once
it enters Self Refresh mode. The clock is internally disabled
FIGURE 35
SELF REFRESH Entry Command
during Self Refresh operation to save power. The minimum
CK
CK
time that the device must remain in Self Refresh mode is tRFC
.
The procedure for exiting Self Refresh requires a sequence of
commands. First, the clock must be stable prior to CKE going
back HIGH. Once Self Refresh Exit is registered, a delay of at
least tXSR must be satisfied before a valid command can be
issued to the device to allow for completion of any internal
refresh in progress.The use of Self Refresh mode introduces
the possibility that an internally timed refresh event can be
missed when CKE is raised for exit from Self Refresh mode.
Upon exit from Self Refresh an extra AUTO REFRESH
command is recommended.
CKE
CS
RAS
CAS
WE
A0-A12
BA0,BA1
= Don't Care
Rev.1.0, 2007-03
10242006-Y557-TZXW
43
QIMONDA [ QIMONDA AG ]
