Kontron CPCI Backplane - Manual (Page 20)

General CPCI Backplane
Page 6 © 2005 Kontron Modular Computers GmbH ID 24229, Rev. 03
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P R E L I M I N A R Y
2.1.1 Clock Skew
Clock skew is the difference between the maximum and minimum propagation delay of any PCI
clock signal. There are two different types of clock skew: backplane and system slot board
clock skew.
The two concepts of backplane and system slot board clock skew are explained as follows.
2.1.2 Backplane Clock Skew
A CompactPCI backplane provides the distribution of clock signals for all of the board slots in
the system. The differences in the trace routing and net topologies contribute to skew and also
define the longest clock delay. Particular attention is paid by the Kontron Modular Computers'
system design to meet overall system clock skew requirements namely through simulation,
testing, and qualification.
2.1.3 System Slot Board Clock Skew
This is the clock skew that may be attributed to the onboard routing differences (if any) of all of
the PCI clocks as well as the skew specification for the type of integrated circuit driver used for
clock distribution. The onboard clock routing is designed to complement the propagation delays
of distributing the clock to a backplane and still meet overall system skew requirements.
3. Backplane Interfaces
3.1 Power Supply Line Input Connections
Distribution of power supply main input power is a function of the individual backplane. Some
backplanes do not have any main input power distribution capability at all whereas others have
several possibilities.
Where a given backplane has distribution capability, main input power is either connected di-
rectly to the backplane power supply connector or, if available, to a separate LINE IN connector.
In both cases, AC as well as DC main input power may be connected depending on the type
of power supply to be used.
Refer to the individual backplane documentation for specific information concerning the con-
nection possibilities.
Warning!
AC/DC power supply units must be installed only with backplanes/systems
connected to an AC mains power and DC/DC power supply units with back-
planes/systems connected only to a DC mains power.
Failure to comply with this warning will result in damage to your equipment.