mpc8544e Freescale Semiconductor, Inc, mpc8544e Datasheet - Page 65

• Manufacturer Part Number: mpc8544e
• Description: Mpc8544e Powerquicc Iii Integrated Processor
• Manufacturer: Freescale Semiconductor, Inc

To illustrate these definitions using real values, consider the case of a CML (Current Mode Logic)
transmitter that has a common mode voltage of 2.25 V and each of its outputs, TD and TD, has a swing
that goes between 2.5 V and 2.0 V. Using these values, the peak-to-peak voltage swing of each signal (TD
or TD) is 500 mV p-p, which is referred as the single-ended swing for each signal. In this example, since
the differential signaling environment is fully symmetrical, the transmitter output’s differential swing
(V
between 500 mV and –500 mV, in other words, V
phase. The peak differential voltage (V
is 1000 mV p-p.
16.2
The SerDes reference clock inputs are applied to an internal PLL whose output creates the clock used by
the corresponding SerDes lanes. The SerDes reference clocks inputs are SD1_REF_CLK and
SD1_REF_CLK for PCI Express1, PCI Express2. SD2_REF_CLK, and SD2_REF_CLK for the PCI
Express3 or SGMII interface, respectively. The following sections describe the SerDes reference clock
requirements and some application information.
16.2.1
Figure 45
Freescale Semiconductor
OD
•
•
) has the same amplitude as each signal’s single-ended swing. The differential output signal ranges
A Volts
B Volts
The supply voltage requirements for XV
SerDes reference clock receiver reference circuit structure
— The SDn_REF_CLK and SDn_REF_CLK are internally AC-coupled differential inputs as
— The external reference clock driver must be able to drive this termination.
SerDes Reference Clocks
shows a receiver reference diagram of the SerDes reference clocks.
shown in
50-Ω termination to SGND_SRDSn (xcorevss) followed by on-chip AC-coupling.
SerDes Reference Clock Receiver Characteristics
MPC8544E PowerQUICC III Integrated Processor Hardware Specifications, Rev. 4
Figure 44. Differential Voltage Definitions for Transmitter or Receiver
Figure
SDn_TX or
SDn_RX
SDn_TX or
SDn_RX
45. Each differential clock input (SDn_REF_CLK or SDn_REF_CLK) has a
Preliminary—Subject to Change Without Notice
Differential Peak-Peak Voltage, V
Freescale Confidential Proprietary
DIFFp
Differential Swing, V
Differential Peak Voltage, V
) is 500 mV. The peak-to-peak differential voltage (V
DD_SRDS2
OD
is 500 mV in one phase and –500 mV in the other
are specified in
ID
or V
DIFFpp
OD
DIFFp
= 2*V
= A – B
= |A – B|
DIFFp
Table 1
(not shown)
High-Speed Serial Interfaces (HSSI)
and
V
cm
Table
= (A + B) / 2
2.
DIFFp-p
65
)