
MPC8641 and MPC8641D Integrated Host Processor Hardware Specifications, Rev. 2
74
Freescale Semiconductor
PCI Express
14.4.3
Differential Receiver (RX) Input Specifications
Table 50 defines the specifications for the differential input at all receivers (RXs). The parameters are
specified at the component pins.
Table 50. Differential Receiver (RX) Input Specifications
Symbol
Parameter
Min
Nom
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.
VRX-DIFFp-p
Differential
Peak-to-Peak
Output Voltage
0.175
—
V
VRX-DIFFp-p = 2*|VRX-D+ – VRX-D-|
See Note 2.
TRX-EYE
Minimum
Receiver Eye
Width
0.4
—
UI
The maximum interconnect media and
Transmitter jitter that can be tolerated by the
Receiver can be derived as TRX-MAX-JITTER =
1 – TRX-EYE= 0.6 UI.
See Notes 2 and 3.
TRX-EYE-MEDIAN-to-MAX
-JITTER
Maximum time
between the jitter
median and
maximum
deviation from
the median.
—
0.3
UI
Jitter is defined as the measurement variation
of the crossing points (VRX-DIFFp-p = 0 V) in
relation to a 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, 3 and 7.
VRX-CM-ACp
AC Peak
Common Mode
Input Voltage
—
150
mV
VRX-CM-ACp = |VRXD+ – VRXD-|/2 – VRX-CM-DC
VRX-CM-DC = DC(avg) of |VRX-D+ – VRX-D-|/2
See Note 2
RLRX-DIFF
Differential
Return Loss
15
—
dB
Measured over 50 MHz to 1.25 GHz with the
D+ and D– lines biased at +300 mV and –300
mV, respectively.
See Note 4
RLRX-CM
Common Mode
Return Loss
6
—
dB
Measured over 50 MHz to 1.25 GHz with the
D+ and D– lines biased at 0 V. See Note 4
ZRX-DIFF-DC
DC Differential
Input Impedance
80
100
120
Ω
RX DC Differential mode impedance. See
Note 5
ZRX-DC
DC Input
Impedance
40
50
60
Ω
Required RX D+ as well as D– DC
Impedance (50 ± 20% tolerance). See Notes
2 and 5.
ZRX-HIGH-IMP-DC
Powered Down
DC Input
Impedance
200 k
—
Ω
Required RX D+ as well as D– DC
Impedance when the Receiver terminations
do not have power. See Note 6.
VRX-IDLE-DET-DIFFp-p
Electrical Idle
Detect Threshold
65
—
mV
VRX-IDLE-DET-DIFFp-p = 2*|VRX-D+ –VRX-D-|
Measured at the package pins of the Receiver