mpc8308 Freescale Semiconductor, Inc, mpc8308 Datasheet - Page 34

• Manufacturer Part Number: mpc8308
• Description: Mpc8308 Powerquicc Ii Pro Processor Hardware Specification
• Manufacturer: Freescale Semiconductor, Inc

PCI Express
10.2.4.1
SD_REF_CLK/SD_REF_CLK are not intended to be used with, and should not be clocked by, a spread
spectrum clock source.
10.3
Figure 26
The DC and AC specification of SerDes data lanes are defined in
Note that external AC-coupling capacitor is required for the PCI Express serial transmission protocol with
the capacitor value defined in specification of PCI Express protocol section.
11 PCI Express
This section describes the DC and AC electrical specifications for the PCI Express bus.
11.1
For more information, see
11.2
Table 33
34
Symbol
t
t
REFCJ
REFPJ
t
REF
lists the PCI Express SerDes clock AC requirements.
SerDes Transmitter and Receiver Reference Circuits
DC Requirements for PCI Express SD_REF_CLK and
AC Requirements for PCI Express SerDes Clocks
SD_REF_CLK
shows the reference circuits for SerDes data lane’s transmitter and receiver.
REFCLK cycle time (for 125 MHz and 100 MHz)
REFCLK cycle-to-cycle jitter. Difference in the period
of any two adjacent REFCLK cycles.
Phase jitter. Deviation in edge location with respect to
mean edge location.
Spread Spectrum Clock
Transmitter
MPC8308 PowerQUICC II Pro Processor Hardware Specification, Rev. 1
Figure 26. SerDes Transmitter and Receiver Reference Circuits
Table 33. SD_REF_CLK and SD_REF_CLK AC Requirements
Parameter Description
Section 10.2, “SerDes Reference Clocks.”
50 Ω
50 Ω
TX n
TX n
RX n
RX n
Min
–50
—
8
Section 11, “PCI Express.”
Typ
10
—
—
50 Ω
50 Ω
Receiver
Max
100
50
—
Freescale Semiconductor
Units
ns
ps
ps
Notes
—
—
—