Global Clocked Mode - Renesas IDT 89HPES48H12G2 User Manual

IDT Clocking
Notes
PES48H12G2 Switch
Port
Clocking
Mode
Local Port
Clocked
Local Port
Clocked
Local Port
Clocked
Local Port
Clocked
PES48H12G2 User Manual
Port Global
Clock Clock
PxCLK with GCLK
SSC
PxCLK with GCLK with
SSC SSC
PxCLK GCLK
PxCLK with GCLK
SSC
Table 4.4 Valid PES48H12G2 System Clocking Configurations (Part 2 of 2)

Global Clocked Mode

A port in global clocked mode uses the global reference clock (GCLK) input for receiving and transmit-
ting serial data.
– A port in this mode does not introduce any requirements on the global reference clock input
beyond those imposed by PCI express.
– Depending on the system configuration, a port in this mode may employ the common Refclk or
separate Refclk architectures defined by the PCIe Base Specification Revision 2.0.
Figure 4.2 shows the clock connection between a PES48H12G2 port and it's link partner, when the
switch port operates in global clocked mode with a common clock configuration.
Figure 4.2 Clocking Connection for a Port in Global Clocked Mode, with a Common Clocked Configuration
Figure 4.3 shows the clock connection between a PES48H12G2 port and it's link partner, when the
switch port operates in global clocked mode with a non-common clock configuration.
Link
Valid
Partner
Config.
Refclk
Same PxCLK as the Yes
switch
Same PxCLK or different No
Refclk as the switch
Different Refclk than the Yes
switch
Different Refclk than the No
switch
Switch
GCLK
Clock
Generator
Link Partner
4 - 4
Notes
Local port clocked with common Refclk architecture
and SSC.
Local port clocked with separate Refclk architecture.
Violates PCI Express +/- 300 ppm clock difference
requirement.
Port
April 5, 2013