Electrical, Power, and Thermal
4.4.9
Write Preamble Duration
The write preamble duration is the measurement from the point when DQS and DQS
start to be driven, to the crossing point of DQS and DQS. Typically, to determine when
DQS and DQS are starting to be driven, timing measurements are made at 0.5xVCC +/
- 50 mV, and 0.5xVCC +/- 100 mV, and then the measurements are linearly
extrapolated back to 0.5xVCC.
Figure 4-8. Write Preamble Duration Timing Diagram
tWPREamb
DQS
(AMB)
0.5xVCC
4.4.10
Write Postamble Duration
The write postamble duration is the measurement from the crossing point of DQS and
DQS, to the point where DQS and DQS start to go into a high impedance state.
Typically, to determine when DQS and DQS are starting to go into a high impedance
state, for DQS, timing measurements are made at Vlow + 50 mV, and Vlow + 100 mV,
and then the measurements are linearly extrapolated back to Vlow. For DQS, timing
measurements are made at Vhigh - 50 mV, and Vhigh - 100 mV, and then the
measurements are extrapolated back to Vhigh.
Figure 4-9. Write Postamble Duration Timing Diagram
tW P S T a m b
0 .5 x V C C
D Q S
(A M B )
Intel® 6400/6402 Advanced Memory Buffer Datasheet
49
INTEL [ INTEL ]
