Data Setup, Hold, and Derating
The total
t
DS (setup time) and
t
DH (hold time) required is calculated by adding the data
sheet
t
DS (base) and
t
DH (base) values to the Δ
t
DS and Δ
t
DH derating values, respec-
tively. Example:
t
DS (total setup time) =
t
DS (base) + Δ
t
DS. For a valid transition, the in-
put signal has to remain above/below V
IH(AC)
/V
IL(AC)
for some time
t
VAC.
Although the total setup time for slow slew rates might be negative (for example, a valid
input signal will not have reached V
IH(AC)
/V
IL(AC)
) at the time of the rising clock transi-
tion), a valid input signal is still required to complete the transition and to reach
V
IH
/V
IL(AC)
.
Setup (
t
DS) nominal slew rate for a rising signal is defined as the slew rate between the
last crossing of V
REF(DC)
and the first crossing of V
IH(AC)min
. Setup (
t
DS) nominal slew
rate for a falling signal is defined as the slew rate between the last crossing of V
REF(DC)
and the first crossing of V
IL(AC)max
. If the actual signal is always earlier than the nominal
slew rate line between the shaded V
REF(DC)
-to-AC region, use the nominal slew rate for
derating value. If the actual signal is later than the nominal slew rate line anywhere be-
tween the shaded V
REF(DC)
-to-AC region, the slew rate of a tangent line to the actual sig-
nal from the AC level to the DC level is used for derating value.
Hold (
t
DH) nominal slew rate for a rising signal is defined as the slew rate between the
last crossing of V
IL(DC)max
and the first crossing of V
REF(DC)
. Hold (
t
DH) nominal slew
rate for a falling signal is defined as the slew rate between the last crossing of V
IH(DC)min
and the first crossing of V
REF(DC)
. If the actual signal is always later than the nominal
slew rate line between the shaded DC-to-V
REF(DC)
region, use the nominal slew rate for
derating value. If the actual signal is earlier than the nominal slew rate line anywhere
between the shaded DC-to-V
REF(DC)
region, the slew rate of a tangent line to the actual
signal from the DC-to-V
REF(DC)
region is used for derating value.
Table 13: Data Setup and Hold Values at 1 V/ns (DQS, DQS# at 2 V/ns) – AC/DC-Based
Symbol gDDR3-1600 gDDR3-1800 gDDR3-2000 gDDR3-2200 Unit Reference
t
DS (base) AC175 – – – – ps V
IH(AC)
/V
IL(AC)
t
DS (base) AC150 30 10 – – ps V
IH(AC)
/V
IL(AC)
t
DS (base) AC135 60 40 68 68 ps V
IH(AC)
/V
IL(AC)
t
DH (base) DC100 65 45 70 70 ps V
IH(DC)
/V
IL(DC)
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Micron and the Micron logo are trademarks of Micron Technology, Inc.
All other trademarks are the property of their respective owners.
This data sheet contains minimum and maximum limits specified over the power supply and temperature range set forth herein.
Although considered final, these specifications are subject to change, as further product development and data characterization some-
times occur.
4Gb: x16 gDDR3 SDRAM Graphics Addendum
Data Setup, Hold, and Derating
CCMTD-1005363231-10344
ddr3_4gb_graphics_addendum 091.pdf - Rev. A 05/16 EN
25
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