
ICS557-01
PCI-EXPRESS GEN1 CLOCK SOURCE
PCIE
IDT PCI-EXPRESS GEN1 CLOCK SOURCE
4
ICS557-01
REV P 072512
PCI-Express Layout Guidelines
Figure 1: PCI-Express Device Routing
Typical PCI-Express (HCSL) Waveform
Common Recommendations for Differential Routing
Dimension or Value
Unit
Figure
Notes
L1 length, Route as non-coupled 50 ohm trace.
0.5 max
inch
1,2
L2 length, Route as non-coupled 50 ohm trace.
0.2 max
inch
1,2
L3 length, Route as non-coupled 50 ohm trace.
0.2 max
inch
1,2
RS
33
ohm
1,2
RT
49.9
ohm
1,2
Differential Routing on a Single PCB
Dimension or Value
Unit
Figure
Notes
L4 length, Route as coupled microstrip 100 ohm differential trace.
2 min to 16 max
inch
1
L4 length, Route as coupled stripline 100 ohm differential trace.
1.8 min to 14.4 max
inch
1
Differential Routing to a PCI Express Connector
Dimension or Value
Unit
Figure
Notes
L4 length, Route as coupled microstrip 100 ohm differential trace.
0.25 to 14 max
inch
2
L4 length, Route as coupled stripline 100 ohm differential trace.
0.225 min to 12.6 max
inch
2
R
S
R
S
R
T
R
T
PCI-Express
Load or
Connector
L1
L2
L3’
L4
L1’
L2’
L3
L4’
ICS557-01
Output
Clock
0.175 V
0.52 V
0.175 V
0.52 V
t
OR
t
OF
500 ps
700 mV
0