
IDT Clocking
PES32NT24xG2 User Manual
2 - 5
January 30, 2013
Notes
Figure 2.5 Clocking Connection for a Port in Local Port Clocked Mode, in a Common Clocked Configuration
Figure 2.6 shows the clock connection between a PES32NT24xG2 port and it’s link partner, when the
switch port operates in local port clocked mode with a non-common clock configuration.
Figure 2.6 Clocking Connection for a Port in Local Port Clocked Mode, in a Non-Common Clocked Configuration
Depending on the stack configuration, some ports may be inactive (see section Stack Configuration on
page 3-5). The PxCLK clock associated with an inactive port is unused by the hardware and its pins should
be connected to ground. For example, if port 0 is configured as x8, ports 1, 2, and 3 become inactive (since
they share the same stack). When configured for local port clocking, port 0 uses P00CLK as it’s reference
clock. P02CLK becomes unused by the hardware and this clock should be connected to Vss on the system
board.
Support for Spread Spectrum Clocking (SSC)
The PES32NT24xG2 supports Spread Spectrum Clocking (SSC) for ports operating in the global
clocked or local port clocked modes. The use of SSC is optional. To use SSC, the following requirements
apply.
–
If the GCLK has SSC, then all ports must operate in global clocked mode and be configured in a
common clocked configuration with their link partners.
–
If the GCLK does not have SSC, then a port may be configured in global clocked mode or local
port clocked mode.
–
If a port is operating in local port clocked mode and the port’s local clock (PxCLK) has SSC, the
following must be met:
• The port must operate in a common-clocked configuration with its link partner.
Port
Link Partner
Clock
Generator
Switch
GCLK
Clock
Generator
PxCLK
Port
Link Partner
Clock
Generator
Switch
GCLK
Clock
Generator
PxCLK
Clock
Generator
Содержание PCI Express 89HPES32NT24xG2
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Страница 24: ...IDT List of Tables PES32NT24xG2 User Manual xiv January 30 2013 Notes...
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Страница 100: ...IDT Switch Core PES32NT24xG2 User Manual 4 22 January 30 2013 Notes...
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