MDS 557-03 E

4

Revision 061005

ICS557-03

PCI-Express Layout Guidelines

PCI-Express Device Routing

Typical PCI-Express (HCSL)

Waveform

Common Recommendations for Differential Routing

Dimension or Value

Unit

L1 length, Route as non-coupled 50 ohm trace.

0.5 max

inch

L2 length, Route as non-coupled 50 ohm trace.

0.2 max

inch

L3 length, Route as non-coupled 50 ohm trace.

0.2 max

inch

33

ohm

49.9

ohm

Differential Routing on a Single PCB

Dimension or Value

Unit

L4 length, Route as coupled microstrip 100 ohm differential trace.

2 min to 16 max

inch

L4 length, Route as coupled stripline 100 ohm differential trace.

1.8 min to 14.4 max

inch

Differential Routing to a PCI Express Connector

Dimension or Value

Unit

L4 length, Route as coupled microstrip 100 ohm differential trace.

0.25 to 14 max

inch

L4 length, Route as coupled stripline 100 ohm differential trace.

0.225 min to 12.6 max inch

R

S

R

S

R

T

R

T

PCI-Express

Load or

Connector

L1

L2

L3’

L4

L1’

L2’

L3

L4’

ICS557-03

Output

Clock

0.175 V

0.52 V

0.175 V

0.52 V

t

OR

t

OF

500 ps

500 ps

700 mV

0