HY5PS1G431CFP_08 Datasheet, PDF (28/45 Pages) Hynix Semiconductor – 1Gb DDR2 SDRAM

HY5PS1G4(8,16)31C(L)FP
HY5PS1G4(8,16)31CFR
4. Differential data strobe
DDR2 SDRAM pin timings are specified for either single ended mode or differential mode depending on the
setting of the EMR “Enable DQS” mode bit; timing advantages of differential mode are realized in system
design. The method by which the DDR2 SDRAM pin timings are measured is mode dependent. In single
ended mode, timing relationships are measured relative to the rising or falling edges of DQS crossing at VREF.
In differential mode, these timing relationships are measured relative to the crosspoint of DQS and its com-
plement, DQS. This distinction in timing methods is guaranteed by design and characterization. Note that
when differential data strobe mode is disabled via the EMR, the complementary pin, DQS, must be tied exter-
nally to VSS through a 20 Ω to 10 KΩ resistor to insure proper operation.
DQS/
DQS
DQ
DM
DQS
t_DQSH
t_DQSL
DQS
t_WPRE
V_IH(ac)
D
V_IL(ac)
t_DS
DMin
D
V_IH(ac)t^DS
DMin
V_IL(ac)
V_IH(dc)
D
V_IL(dc)
t_DH
DMin
t_WPST
D
t_{DH VIH(dc)}
DMin
V_IL(dc)
Figure -- Data input (write) timing
CK
CK/CK
CK
DQS/DQS
DQ
t_CH
t_CL
DQS
DQS
t_RPRE
t_DQSQmax
Q
t_QH
Q
Q
t_DQSQmax
Figure -- Data output (read) timing
t_RPST
Q
t_QH
5. AC timings are for linear signal transitions. See System Derating for other signal transitions.
6. All voltages referenced to VSS.
7. These parameters guarantee device behavior, but they are not necessarily tested on each device. They
may be guaranteed by device design or tester correlation.
8. Tests for AC timing, IDD, and electrical (AC and DC) characteristics, may be conducted at nominal refer-
ence/supply voltage levels, but the related specifications and device operation are guaranteed for the full
voltage range specified.
Rev. 0.7 / Nov. 2008
28