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1GB-DDR3L-AS4C64M16D3L Datasheet, PDF (12/90 Pages) Alliance Semiconductor Corporation – JEDEC Standard Compliant
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1Gb DDR3L – AS4C64M16D3L
Register Definition
 Programming the Mode Registers
For application flexibility, various functions, features, and modes are programmable in four Mode Registers,
provided by the DDR3L SDRAM, as user defined variables and they must be programmed via a Mode Register Set
(MRS) command. As the default values of the Mode Registers are not defined, contents of Mode Registers must
be fully initialized and/or re-initialized, i.e., written, after power up and/or reset for proper operation. Also the
contents of the Mode Registers can be altered by re-executing the MRS command during normal operation. When
programming the mode registers, even if the user chooses to modify only a sub-set of the MRS fields, all address
fields within the accessed mode register must be redefined when the MRS command is issued. MRS command
and DLL Reset do not affect array contents, which mean these commands can be executed any time after power-
up without affecting the array contents.
The mode register set command cycle time, tMRD is required to complete the write operation to the mode
register and is the minimum time required between two MRS commands shown in Figure 6.
Figure 6. tMRD timing
T0
T1
T2
CK#
CK
COMMAND VALID
VALID
VALID
ADDRESS
VALID
VALID
VALID
CKE
Ta0
Ta1
Tb0
Tb1
Tb2
Tc0
MRS
VALID
NOP/DES
NOP/DES
VALID
VALID
MRS
VALID
NOP/DES
NOP/DES
VALID
VALID
Tc1
VALID
VALID
Tc2
VALID
VALID
Settings
Old Settings
ODT
ODT
RTT_Nom ENABLED prior and/or after MRS command
VALID
VALID
ODTLoff + 1
RTT_Nom DISABLED prior and after MRS command
VALID
VALID
VALID
VALID
tMRD
Updating Settings
tMOD
VALID
VALID
VALID
VALID
VALID
New Settings
VALID
VALID
VALID
TIME BREAK
Don't Care
The MRS command to Non-MRS command delay, tMOD, is require for the DRAM to update the features except
DLL reset, and is the minimum time required from an MRS command to a non-MRS command excluding NOP and
DES shown in Figure 7.
Confidential
12
Rev. 2.0
Aug. /2014
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