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Unbuffered DIMM
11.2 V
Tolerances
REF
The dc-tolerance limits and ac-noise limits for the reference voltages V
V
(t) as a function of time. (V
REF
REF
V
(DC) is the linear average of V
REF
thermore V
(t) may temporarily deviate from V
REF
voltage
The voltage levels for setup and hold time measurements V
"V
" shall be understood as V
REF
This clarifies, that dc-variations of V
which setup and hold is measured. System timing and voltage budgets need to account for V
data-eye of the input signals.
This also clarifies that the DRAM setup/hold specification and derating values need to include time and voltage associated with V
Timing and voltage effects due to ac-noise on V
datasheet
stands for V
and V
REFCA
REFDQ
(t) over a very long period of time (e.g. 1 sec). This average has to meet the min/max requirements of V
REF
(DC) by no more than ± 1% V
REF
Figure 2. Illustration of VREF(DC) tolerance and VREF ac-noise limits
(AC), V
IH
(DC), as defined in Figure 2.
REF
affect the absolute voltage a signal has to reach to achieve a valid high or low level and therefore the time to
REF
up to the specified limit (+/-1% of V
REF
and V
are illustrate in Figure 2. It shows a valid reference voltage
REFCA
REFDQ
likewise).
.
DD
(DC), V
(AC) and V
(DC) are dependent on V
IH
IL
IL
(DC) deviations from the optimum position within the
REF
) are included in DRAM timings and their associated deratings.
DD
- 14 -
Rev. 1.0
DDR3L SDRAM
REF
V
DD
V
SS
time
.
REF
ac-noise.
REF
. Fur-
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