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Low-Power Module Memory Bus Simulation Methodology
6.1.1
Flight Time Determination for Setup Time
The maximum flight time measurement is used to determine the setup time of a memory signal.
Both the rising and falling edges should be considered. Figure 6 shows the determination of
maximum flight time for the rising edge of a memory signal.
Figure 6. Flight Time (Rising Edge)
The flight time of the rising edge is measured between the driver and receiver at 1.4 V since the
threshold switching voltage of the SDRAM is at this voltage.
However, if the edge rate (20% - 80% measurement) of the flight time is less than 1 V/ns, then the
flight time is measured between the driver at 1.4 V and the receiver at 2.0 V (V
by subtracting 600 ps.
The maximum flight time is the greater of the two measurements.
12
Driver
Receiver
2.0 V
1.4 V
TFlight
0.8 V
t1
t2
A6433-01
), and derating it
ih
Application Note
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