mpc8378e Freescale Semiconductor, Inc, mpc8378e Datasheet - Page 70

• Manufacturer Part Number: mpc8378e
• Description: Powerquicc Ii Pro Processor Hardware Specifications
• Manufacturer: Freescale Semiconductor, Inc

PCI Express
15.4.2
The Tx eye diagram in
Figure
must be met for the transmitter. Both diagrams must be aligned in time using the jitter median to locate the
center of the eye diagram. The different eye diagrams differ in voltage depending on whether it is a
70
Common mode return
loss
DC differential Tx
impedance
Transmitter DC
impedance
Lane-to-Lane output
skew
AC coupling capacitor
Crosslink random
timeout
Note:
1
2
3
4
5
6
7
No test load is necessarily associated with this value.
Specified at the measurement point into a timing and voltage compliance test load as shown in
any 250 consecutive Tx UIs. (Also refer to the transmitter compliance eye diagram shown in
A T
transmitter collected over any 250 consecutive Tx UIs. The T
Tx jitter budget collected over any 250 consecutive Tx UIs. It should be noted that the median is not the same as the mean.
The jitter median describes the point in time where the number of jitter points on either side is approximately equal as opposed
to the averaged time value.
The transmitter input impedance will result in a differential return loss greater than or equal to 12 dB and a common mode
return loss greater than or equal to 6 dB over a frequency range of 50 MHz to 1.25 GHz. This input impedance requirement
applies to all valid input levels. The reference impedance for return loss measurements is 50 Ω to ground for both the D+ and
D– line (that is, as measured by a vector network analyzer with 50-Ω probes, see
C
Measured between 20%–80% at transmitter package pins into a test load as shown in
See Section 4.3.1.8 of the PCI Express Base Specifications , Rev 1.0a.
See Section 4.2.6.3 of the PCI Express Base Specifications , Rev 1.0a.
TX
TX-EYE
Parameter
, is optional for the return loss measurement.
48) in place of any real PCI Express interconnect + Rx component. There are two eye diagrams that
= 0.70 UI provides for a total sum of deterministic and random jitter budget of T
Transmitter Compliance Eye Diagrams
Table 57. Differential Transmitter (Tx) Output Specifications (continued)
MPC8378E PowerQUICC II Pro Processor Hardware Specifications, Rev. 3
Measured over 50 MHz to
1.25 GHz.
Tx DC differential mode low
impedance
Required Tx D+ as well as D–
DC impedance during all
states
Static skew between any two
transmitter lanes within a
single link
All transmitters should be AC
coupled. The AC coupling is
required either within the
media or within the
transmitting component itself.
This random timeout helps
resolve conflicts in crosslink
configuration by eventually
resulting in only one
downstream and one
upstream port.
Figure 46
Conditions
is specified using the passive compliance/test measurement load (see
Z
L
TX-DIFF-DC
RL
T
Symbol
TX-SKEW
TX-EYE-MEDIAN-to-MAX-JITTER
Z
crosslink
TX-DC
C
TX-CM
TX
Min
80
40
75
—
6
0
Figure
Figure 48
Typical
48). Note that the series capacitors,
median is less than half of the total
100
—
—
—
—
—
TX-JITTER-MAX
Figure
Figure 48
for both V
Freescale Semiconductor
500 +
46.)
Max
2 UI
120
200
—
—
1
and measured over
= 0.30 UI for the
TX-D+
Units
ms
dB
ps
nF
Ω
Ω
and V
Notes
TX-D-
—
—
—
—
4
7
.