PCI Express
Table 61. Differential Transmitter (TX) Output Specifications
Symbol
Parameter
Min Nominal Max Units
Comments
UI
Unit Interval
399.88
400
400.12 ps Each UI is 400 ps ± 300 ppm. UI does not account
for Spread Spectrum Clock dictated variations. See
Note 1.
V
V
Differential
Peak-to-Peak
Output Voltage
0.8
—
1.2
V
V
= 2*|V
- V
| See Note 2.
TX-D-
TX-DIFFp-p
TX-DIFFp-p
TX-D+
De- Emphasized –3.0
Differential
–3.5
-4.0
dB Ratio of the V
of the second and following
TX-DIFFp-p
TX-DE-RATIO
bits after a transition divided by the V
of
TX-DIFFp-p
Output Voltage
(Ratio)
the first bit after a transition. See Note 2.
T
T
Minimum TX Eye 0.70
Width
—
—
—
UI The maximum Transmitter jitter can be derived as
= 1 - T = 0.3 UI.
TX-EYE
T
TX-MAX-JITTER
TX-EYE
See Notes 2 and 3.
Maximum time
between the jitter
median and
—
0.15
UI Jitter is defined as the measurement variation of the
TX-EYE-MEDIAN-to-
crossing points (V = 0 V) in relation to a
MAX-JITTER
TX-DIFFp-p
recovered TX UI. A recovered TX UI is calculated
over 3500 consecutive unit intervals of sample
data. Jitter is measured using all edges of the 250
consecutive UI in the center of the 3500 UI used for
calculating the TX UI. See Notes 2 and 3.
maximum
deviation from
the median.
T
, T
D+/D- TX Output 0.125
Rise/Fall Time
—
—
—
UI See Notes 2 and 5
TX-RISE TX-FALL
V
RMS AC Peak
Common Mode
Output Voltage
—
20
mV
V
V
= RMS(|V
+ V
|/2 - V
)
TX-CM-DC
TX-CM-ACp
TX-CM-ACp
TXD+
of |V
TXD-
+ V
= DC
|/2
TX-CM-DC
(avg)
TX-D+
TX-D-
See Note 2
V
Absolute Delta of
DC Common
Mode Voltage
During L0 and
Electrical Idle
0
—
100
mV |V
- V
TX-CM-DC-ACTIVE-
TX-CM-DC (during L0) TX-CM-Idle-DC (During Electrical
|<=100 mV
IDLE-DELTA
Idle)
V
V
= DC
of |V
+ V
|/2 [L0]
TX-D-
TX-CM-DC
(avg)
TX-D+
= DC
of |V
+ V |/2
TX-CM-Idle-DC
(avg)
TX-D+
TX-D-
[Electrical Idle]
See Note 2.
V
Absolute Delta of
DC Common
Mode between
D+ and D–
0
0
—
25
mV |V
- V
= DC
= DC
| <= 25 mV
TX-CM-DC-D-
TX-CM-DC-LINE-DELTA
TX-CM-DC-D+
TX-CM-DC-D+
V
V
of |V
|
(avg)
(avg)
TX-D+
of |V
|
TX-CM-DC-D-
TX-D-
See Note 2.
V
V
Electrical Idle
differential Peak
Output Voltage
—
—
20
mV
V
= |V
-V
| <= 20
TX-IDLE-DIFFp
TX-IDLE-DIFFp
TX-IDLE-D+
TX-IDLE-D-
mV
See Note 2.
The amount of
voltage change
allowed during
Receiver
600
mV The total amount of voltage change that a
transmitter can apply to sense whether a low
impedance Receiver is present. See Note 6.
TX-RCV-DETECT
Detection
V
The TX DC
Common Mode
Voltage
0
—
3.6
V
The allowed DC Common Mode voltage under any
conditions. See Note 6.
TX-DC-CM
MPC8572E PowerQUICC III Integrated Processor Hardware Specifications, Rev. 4
Freescale Semiconductor
83
FREESCALE [ Freescale ]
