1000BASE-T/100BASE-TX/10BASE-T Physical Layer Compliance Tests Manual
Intel Confidential
139
100Base-TX Test Procedure for the 82544 Chip
Following the above method should ensure a good trigger with minimal added jitter.
4. Use the horizontal offset to position the waveform, as shown in
.
5. Change the Oscilloscope’s signal acquisition mode to “Single Sequence” and/or “One-Shot”
acquisition mode. [Do NOT use averaging. Do NOT use sampling mode.]
6. Push the trigger button; then observe the captured waveform. Keep doing manual triggers,
until a pulse is acquired that has mid-level “shoulders” on both sides; with each shoulder being
at least 20 nseconds wide (see
).
7. Select the horizontal cursors. Move one cursor to +Vout, and move the other cursor to -Vout.
The differential output voltage is the difference between the two cursors.
See
for measurement points. +Vout is the difference (delta) between the average MLT-3
mid-level (~0 volts), and the average peak positive output voltage. This does not include overshoot.
If there is ripple or overshoot at either level, the amplitude cursor may slice through it.
Although it is not specifically mentioned in specification 9.1.2.2, -Vout should be between –950
mV and –1050 mV.
provide examples of data for differential output
voltage.
Figure I-3. Positive Peak Differential Output Voltage
Pulse Width Triggering
Triggering information is provided to give a good starting point for measurement. The
following guidelines will help the tester achieve the most stable display.
1. Set the trigger level as specified in the above table.
2. Select pulse width triggering.
3. Set the upper bound parameter to approximately 400 ns and the lower bound
parameter to approximately 125 ns.
4. Set the trigger mode to normal.
5. Increase the lower bound parameter gradually until the triggering is lost.
6. Decrease the lower bound parameter slowly in 6 ns increments until triggering
resumes.
7. Decrease the upper bound parameter until it is 6 ns to 15 ns above the lower trigger
bound parameter.
