ICS841664AGI REVISION A JULY 15, 2013

13

©2013 Integrated Device Technology, Inc.

ICS841664I Data Sheet

FEMTOCLOCK® CRYSTAL-TO-HCSL CLOCK GENERATOR

Applications Information, continued

Recommended Termination

Figure 3A is the recommended source termination for applications

where the driver and receiver will be on a separate PCBs. This

termination is the standard for PCI Express™and HCSL output types.

All traces should be 50

Ω impedance single-ended or

100

Ω differential.

Figure 3A. Recommended Source Termination (where the driver and receiver will be on separate PCBs)

Figure 3B is the recommended termination for applications where a

point-to-point connection can be used. A point-to-point connection

contains both the driver and the receiver on the same PCB. With a

matched termination at the receiver, transmission-line reflections will

be minimized. In addition, a series resistor (Rs) at the driver

offers flexibility and can help dampen unwanted reflections.

The optional resistor can range from 0

Ω to 33Ω. All traces

should be 50

Ω impedance single-ended or 100Ω differential.

Figure 3B. Recommended Termination (where a point-to-point connection can be used)

0-0.2"

PCI Expres s

L1

L1

1-14"

Driver

Rs

0.5" Max

L3

L4

L2

L2

49.9 +/- 5%

22 to 33 +/-5%

Rt

L3

L4

L5

0.5 - 3.5"

L5

Connector

PCI Expres s

Add-in Card

PCI Expres s

0-0.2"

PCI Expres s

0-0.2"

0-18"

L1

L1

Rs

Driver

0.5" Max

L3

L3

L2

L2

49.9 +/- 5%

0 to 33

0 to 33

Rt