K4N51163QC-ZC Datasheet, PDF (52/64 Pages) Samsung semiconductor – 512Mbit gDDR2 SDRAM

K4N51163QC-ZC
512M gDDR2 SDRAM
Self Refresh Operation
The gDDR2 SDRAM device has a built-in timer to accommodate Self Refresh operation. The Self Refresh Command is defined by hav-
ing CS, RAS, CAS and CKE held low with WE high at the rising edge of the clock. ODT must be turned off before issuing Self Refresh
command, by either driving ODT pin low or using EMRS command. Once the Command is registered, CKE must be held low to keep the
device in Self Refresh mode. When the gDDR2 SDRAM has entered Self Refresh mode all of the external signals except CKE, are
“don’t care”. Since CKE is an SSTL 2 input, VREF must be maintained during Self Refresh operation. The DRAM initiates a minimum of
one one Auto Refresh command internally within tCKE period once it enters Self Refresh mode. The clock is internally disabled during
Self Refresh Operation to save power. The minimum time that the gDDR2 SDRAM must remain in Self Refresh mode is tCKE. The user
may change the external clock frequency or halt the external clock one clock after Self-Refresh entry is registered, however, the clock
must be restarted and stable before the device can exit Self Refresh operation. Once Self Refresh Exit command is registered, a delay
equal or longer than the tXSNR or tXSRD must be satisfied before a valid command can be issued to the device. CKE must remain high
for the entire Self Refresh exit period tXSRD for proper operation. Upon exit from Self Refresh, the gDDR2 SDRAM can be put back into
Self Refresh mode after tXSRD expires. NOP or deselect commands must be registered on each positive clock edge during the Self
Refresh exit interval. ODT should also be turned off during tXSRD. Upon exit from Self Refresh, the gDDR2 SDRAM requires a mini-
mum of one extra auto refresh command before it is put back into Self Refresh mode.
T0
T1
T2
tCK
tCH tCL
CK
CK
CKE
ODT
CMD
V_IL(AC)
tIS
T3
T4
T5
T6
tRP*
tAOFD
VIL(AC)
tIS
tIS tIH
V_IH(AC) _{Self VIH(DC)}
V_IL(AC) Refresh VIL(DC)
Tm
Tn
VIH(AC)
tIS
> = tXSNR
> = tXSRD
NOP
NOP
NOP
Valid
- Device must be in the “All banks idle” state prior to entering Self Refresh mode.
- ODT must be turned off tAOFD before entering Self Refresh mode, and can be turned on again when tXSRD timing is satisfied.
- tXSRD is applied for a Read or a Read with autoprecharge command.
- tXSNR is applied for any command except a Read or a Read with autoprecharge command.
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Rev 1.5 Oct. 2005