Teledyne Lecroy PCI Express 3.0 Mid-Bus Probe, Installation And Usage Manual

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PCIe 3.0 Mid‐Bus Probe Installation and Usage Guide 13
Probe Connection to Analyzer Teledyne LeCroy
3.3 Probe Connection to Analyzer
The bus signals captured by the mid‐bus probe are connected to a mid‐bus probe pod for
amplification. This reduces the load imposed by the mid‐bus probe on the target system,
while allowing a longer cable to attach to the Teledyne LeCroy PCI Express protocol
analyzer. The Teledyne LeCroy PCI Express protocol analyzer can then interpret these
signals for full decoding and protocol analysis.
3.4 Probe Keepout Volume
As with any connection to a PCB, sufficient clearance must be allowed around the point
where the probe will connect. This is defined as the keep‐out volume, which must be kept
clear of other components mounted on the PCB.
The probe keepout volumes are shown in the diagrams in “Probe Footprints” on page 9 .
3.5 Reference Clock Probe Attachment
Should SSC clocking be used in the system under test or if the link varies the bit rate by
more than 100 MHz ± 300ppm (see Section 4.3.7 of Base Spec 3.0), a reference clock tap
may be required. The connection from the reference clock to the analyzer is a 3‐pin
header (1 by 3, 0.050” center spacing) which is placed on the clock signal transmission
line of the DUT. The PE014UCA‐X Reference Clock Cable provides a three‐pin micro socket
that connects from this header to the CLK IN port on the Mid‐Bus Pod.
If the reference clock is sampled by tapping off an existing clock, the header shall be
located on the existing clock transmission line, where a high impedance clock probe from
the mid‐bus probe is connected with no significant loading effects. In the case of a
dedicated clock, the header shall be located at the end of a dedicated clock transmission
line without termination, where a 50‐Ohm cable is connected and the termination for the
clock signal is provided on the mid‐bus probe board.
The connectivity of the clock header pins follows the following table:
TABLE 3.3: Clock Header Pins
Note:
The analyzer is not sensitive to the polarity of the reference clock. Therefore, the probe can be
plugged onto the pin header in either orientation.
The following 3‐pin header can be used for the reference clock:

Samtec Part No: TMS‐103 (Vertical Orientation)
Signal Pin Number
REFCLKp 1 (or 3)
Unused 2
REFCLKn 3 (or 1)