mpc8569e Freescale Semiconductor, Inc, mpc8569e Datasheet - Page 78

• Manufacturer Part Number: mpc8569e
• Description: Mpc8569e Powerquicc Iii Integrated Processor Hardware Specifications
• Manufacturer: Freescale Semiconductor, Inc

High-Speed SerDes Interfaces (HSSI)
2.9.1
The SerDes utilizes differential signaling to transfer data across the serial link. This section defines terms used in the description
and specification of differential signals.
The below figure shows how the signals are defined. For illustration purposes only, one SerDes lane is used in the description.
The following figure shows the waveform for either a transmitter output (SDn_TX and SDn_TX) or a receiver input (SDn_RX
and SDn_RX). Each signal swings between A volts and B volts where A > B.
Using this waveform, the definitions are as shown in the following list. To simplify the illustration, the definitions assume that
the SerDes transmitter and receiver operate in a fully symmetrical differential signaling environment:
Single-Ended Swing
Differential Output Voltage, V
Differential Input Voltage, V
Differential Peak Voltage, V
Differential Peak-to-Peak, V
Differential Waveform
78
A Volts
B Volts
Signal Terms Definition
MPC8569E PowerQUICC III Integrated Processor Hardware Specifications, Rev. 0
Figure 38. Differential Voltage Definitions for Transmitter or Receiver
SDn_TX or
SDn_RX
SDn_TX or
SDn_RX
The transmitter output signals and the receiver input signals SD_TX, SD_TX, SD_RX and SD_RX
each have a peak-to-peak swing of A – B volts. This is also referred as each signal wire’s
single-ended swing.
The differential output voltage (or swing) of the transmitter, V
the two complimentary output voltages: V
or negative.
The differential input voltage (or swing) of the receiver, V
complimentary input voltages: V
negative.
The peak value of the differential transmitter output signal or the differential receiver input signal
is defined as the differential peak voltage, V
Since the differential output signal of the transmitter and the differential input signal of the receiver
each range from A – B to –(A – B) volts, the peak-to-peak value of the differential transmitter
output signal or the differential receiver input signal is defined as differential peak-to-peak voltage,
V
twice of the differential peak. For example, the output differential peak-peak voltage can also be
calculated as V
The differential waveform is constructed by subtracting the inverting signal (SD_TX, for example)
from the non-inverting signal (SD_TX, for example) within a differential pair. There is only one
DIFFp
DIFFp-p
ID
DIFFp-p
OD
(or Differential Input Swing):
(or Differential Output Swing):
Differential Peak-Peak Voltage, V
= 2 × V
TX-DIFFp-p
DIFFp
Differential Swing, V
Differential Peak Voltage, V
= 2 × |(A – B)| volts, which is twice the differential swing in amplitude, or
= 2 × |V
SD_RX
OD
|.
– V
ID
DIFFpp
SD_TX
or V
SD_RX
DIFFp
OD
DIFFp
= 2 * V
– V
. The V
= |A – B| volts.
= A – B
SD_TX.
= |A – B|
DIFFp
ID
ID
, is defined as the difference of the two
The V
value can be either positive or
(not shown)
OD
, is defined as the difference of
OD
value can be either positive
V
Freescale Semiconductor
cm
= (A + B)/2