mpc8308 Freescale Semiconductor, Inc, mpc8308 Datasheet - Page 38

• Manufacturer Part Number: mpc8308
• Description: Mpc8308 Powerquicc Ii Pro Processor Hardware Specification
• Manufacturer: Freescale Semiconductor, Inc

PCI Express
11.4.2
The TX eye diagram in
(Figure
that 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
transition bit or a de-emphasized bit. The exact reduced voltage level of the de-emphasized bit is always
relative to the transition bit.
The eye diagram must be valid for any 250 consecutive UIs.
A recovered TX UI is calculated over 3500 consecutive unit intervals of sample data. The eye diagram is
created using all edges of the 250 consecutive UI in the center of the 3500 UI used for calculating the TX
UI.
38
Crosslink random timeout
Notes:
1. No test load is necessarily associated with this value.
2. Specified at the measurement point into a timing and voltage compliance test load as shown in
3. A T
4. The transmitter input impedance results in a differential return loss greater than or equal to 12 dB and a common mode return
5. Measured between 20% and 80% at transmitter package pins into a test load as shown in
6. See Section 4.3.1.8 of the PCI Express Base Specifications , Rev 1.0a.
7. See Section 4.2.6.3 of the PCI Express Base Specifications , Rev 1.0a.
any 250 consecutive TX UIs. (Also refer to the transmitter compliance eye diagram shown in
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.
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
is optional for the return loss measurement.
V
TX-D-
TX-EYE
Parameter
29) in place of any real PCI Express interconnect + RX component. There are two eye diagrams
.
= 0.70 UI provides for a total sum of deterministic and random jitter budget of T
Transmitter Compliance Eye Diagrams
It is recommended that the recovered TX UI be calculated using all edges in
the 3500 consecutive UI interval with a fit algorithm using a minimization
merit function (that is, least squares and median deviation fits).
Table 34. Differential Transmitter (TX) Output Specifications (continued)
MPC8308 PowerQUICC II Pro Processor Hardware Specification, Rev. 1
Figure 27
T
Symbol
crosslink
is specified using the passive compliance/test measurement load
This random timeout helps
resolve conflicts in
crosslink configuration by
eventually resulting in only
one Downstream and one
Upstream Port.
Comments
NOTE
TX-EYE-MEDIAN-to-MAX-JITTER
Min
0
Figure
29). Note that the series capacitors, C
Typical
—
median is less than half of the total
TX-JITTER-MAX
Figure 29
Figure
Figure 29
Max
1
Freescale Semiconductor
27.)
for both V
and measured over
= 0.30 UI for the
Units
ms
TX-D+
Notes
and
7
TX
,