Teledyne LeCroy QPHY-USB3-Tx-Rx - Manual (Page 26)

26
917719 Rev A
QPHY-USB3-TX-RX TEST DESCRIPTIONS
Pre-Test
Test for Ping.LFPS Support
By utilizing the PeRT
3
, this test checks to see if the Product under test supports the required Ping.LFPS mode
that the PeRT
3
uses to stimulate the PUT to generate the appropriate compliance patterns for eac h test . The
PeRT
3
sends the Init.LFPS command to the PUT to stimulate the P UT to enter compliance mode. Then, the
PeRT
3
sends a Ping.LFPS command to the PUT and the oscilloscope checks that the appropriate CP0 pattern is
being transmitted by the P UT. Then, another Ping.LFPS command is sent and the oscilloscope checks that the
appropriate CP1 pattern is being transmitted by the PUT. This is repeated for all compliance patterns.
Test 1.1 Low Frequency Periodic Signaling (LFPS)
The purpose of this test group is to verify the voltage and timing parameters of the Low Frequency Periodic
Signaling (LFPS) are within the specification limits.
At the completion of the Low Frequency Periodic Signaling Test the oscillosc ope is in the following configuration:
Figure 10 - Oscilloscope Configuration after LFPS Test
On this screen there are 4 traces visible. F1 is the result of the subtraction of C1 and C2. This is the differential
LFPS trace. F2 is the result of the addition of C1 and C2 divided by 2. This is the common mode LFPS trace. F3
shows only the first 6 bursts of the differential LFPS trace and F4 shows only the first 6 bursts of the common
mode LFPS trace.
The burst width is measured in parameter P1. P2 is used to measure the time between the bursts (tRepeat ). P3
measures the period of the signal within the burst. P4 and P5 measure the 20-80% rise time and 80-20% fall time
of the pulses within the burst. P6 and P7 meas ure the duty cycle and amplitude of the signals within the burst. P8
measures the peak-to-peak amplitude of the Common Mode Trace.