HY5PS1G821M Datasheet, PDF (13/79 Pages) Hynix Semiconductor – 1Gb DDR2 SDRAM(DDP)

1HY5PS12421(L)M
HY5PS12821(L)M
1. If OCD calibration is not used, EMRS OCD Default command (A9=A8= A7=1) followed by EMRS OCD
Calibration Mode Exit command (A9=A8=A7=0) must be issued with other operating parameters of
EMRS.
2. The DDR2 SDRAM is now ready for normal operation.
*1) To guarantee ODT off, VREF must be valid and a low level must be applied to the ODT pin.
*2) Sequence 5 and 6 may be performed between 8 and 9.
Initialization Sequence after Power Up
tCHtCL
CK
/CK
tIS
CKE
ODT
Command
NOP
PRE
ALL
EMRS
MRS
PRE
ALL
REF
400ns
tRP
tMRD
tMRD
tRP
DLL
ENABLE
DLL
RESET
REF
tRFC
tRFC
min. 200 Cycle
MRS
EMRS
EMRS
ANY
CMD
tMRD
Follow OCD
tOIT
Flowchart
OCD
Default
OCD
CAL. MODE
EXIT
2.3.2 Programming the Mode and Extended Mode Registers
For application flexibility, burst length, burst type, CAS latency, DLL reset function, write recovery time(tWR)
are user defined variables and must be programmed with a Mode Register Set (MRS) command. Addition-
ally, 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 pro-
grammed with an Extended Mode Register Set (EMRS) command. Contents of the Mode Register(MR) or
Extended Mode Registers(EMR(#)) can be altered by re-executing the MRS and EMRS Commands. If the
user chooses to modify only a subset of the MRS or EMRS variables, all variables must be redefined when
the MRS or EMRS commands are issued.
MRS, EMRS and Reset DLL do not affect array contents, which means reinitialization including those can be
executed any time after power-up without affecting array contents.
Rev. 0.2 / Oct. 2005
13