46DR83200A Datasheet, PDF (33/48 Pages) Integrated Silicon Solution, Inc – 32Mx8, 16Mx16 DDR2 DRAM

IS43/46DR83200A, IS43/46DR16160A
Power-up and Initialization Sequence (cont'd)
f) Issue an EMRS command to EMR(3).
g) Issue EMRS to enable DLL.
h) Issue a Mode Register Set command for DLL reset.
i) Issue a precharge all command.
j) Issue 2 or more auto-refresh commands.
k) Issue a MRS command with LOW to A8 to initialize device operation. (i.e. to program operating parameters without
resetting the DLL.)
l) At least 200 clocks after step h, execute OCD Calibration (Off Chip Driver impedance adjustment).
If OCD calibration is not used, EMRS to EMR(1) to set OCD Calibration Default (A9=A8=A7=HIGH) followed by
EMRS to EMR(1) to exit OCD Calibration Mode (A9=A8=A7=LOW) must be issued with other operating parameters of
EMR(1).
m) The DDR2 SDRAM is now ready for normal operation.
CK
/CK
CKE
ODT
Command
tCHtCL
tIS
NOP
PRE
ALL
EMRS
MRS
PRE
ALL
REF
400ns
tRP
tMRD
tMRD
tRP
DLL
ENABLE
DLL
RESET
tIS
REF
tRFC
tRFC
min 200 Cycle
MRS
EMRS
EMRS
ANY
CMD
tMRD
Follow OCD
tOIT
Flowchart
OCD
Default
OCD
CAL. MODE
EXIT
Initialization Sequence after Power-Up
Programming the Mode and Extended Mode Registers
For application flexibility, burst length, burst type, CAS latency, DLL reset function, write recovery time (WR) are user
defined variables and must be programmed with a Mode Register Set (MRS) command. Additionally, DLL disable
function, driver impedance, additive CAS latency, ODT (On Die Termination), single-ended strobe, and OCD (off chip
driver impedance adjustment) are also user defined variables and must be programmed with an Extended Mode
Register Set (EMRS) command. Contents of the Mode Register or Extended Mode Registers can be altered by re-
executing the MRS or EMRS Commands. Even if the user chooses to modify only a subset of the MR, or EMR(1),
EMR(2), or EMR(3) variables, all variables within the addressed register must be redefined when the MRS or EMRS
commands are issued.
MRS, EMRS and Reset DLL do not affect memory array contents, which means re-initialization including those can be
executed at any time after power-up without affecting memory array contents.
Integrated Silicon Solution, Inc. — www.issi.com
33
Rev. D
08/16/2012