High-Speed Serial Interfaces (HSSI)
SDn_REF_CLK
SDn_REF_CLK
SDn_REF_CLK
SDn_REF_CLK
Figure 53. Single-Ended Measurement Points for Rise and Fall Time Matching
The other detailed AC requirements of the SerDes Reference Clocks is defined by each interface protocol
based on application usage. Refer to the following sections for detailed information:
•
•
•
Section 8.3.2, “AC Requirements for SGMII SD2_REF_CLK and SD2_REF_CLK”
Section 16.2, “AC Requirements for PCI Express SerDes Reference Clocks”
Section 17.2, “AC Requirements for Serial RapidIO SD1_REF_CLK and SD1_REF_CLK”
15.2.4.1 Spread Spectrum Clock
SD1_REF_CLK/SD1_REF_CLK are designed to work with a spread spectrum clock (+0 to –0.5%
spreading at 30–33 KHz rate is allowed), assuming both ends have same reference clock. For better results,
a source without significant unintended modulation should be used.
SD2_REF_CLK/SD2_REF_CLK are not to be used with, and should not be clocked by, a spread spectrum
clock source.
15.3 SerDes Transmitter and Receiver Reference Circuits
Figure 54 shows the reference circuits for SerDes data lane’s transmitter and receiver.
SD1_RXn or
SD2_RXn
SD1_TXn or
SD2_TXn
50 Ω
50 Ω
50 Ω
50 Ω
Receiver
Transmitter
SD1_TXn or
SD2_TXn
SD1_RXn or
SD2_RXn
Figure 54. SerDes Transmitter and Receiver Reference Circuits
The DC and AC specification of SerDes data lanes are defined in each interface protocol section below
(PCI Express, Serial Rapid IO or SGMII) in this document based on the application usage:
•
Section 8.3, “SGMII Interface Electrical Characteristics”
MPC8572E PowerQUICC III Integrated Processor Hardware Specifications, Rev. 4
Freescale Semiconductor
81
FREESCALE [ Freescale ]
