PCI Express
Table 53. Differential Receiver (RX) Input Specifications (continued)
Symbol
V
RX-CM-ACp
Parameter
AC peak
common mode
input voltage
Differential
return loss
Common mode
return loss
DC differential
input impedance
DC input
impedance
Powered down
DC input
impedance
Electrical idle
detect threshold
Unexpected
electrical idle
enter detect
threshold
integration time
Min
—
Nom
—
Max
150
Unit
mV
Comments
V
RX-CM-ACp
= |V
RXD+
– V
RXD-
|/2 + V
RX-CM-DC
V
RX-CM-DC
= DC
(avg)
of |V
RX-D+
+ V
RX-D–
|
÷
2.
See Note 2.
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.
Measured over 50 MHz to 1.25 GHz with the D+
and D– lines biased at 0 V. See Note 4.
RX DC differential mode impedance. See Note 5.
Required RX D+ as well as D– DC impedance
(50 ± 20% tolerance). See Notes 2 and 5.
Required RX D+ as well as D– DC impedance
when the receiver terminations do not have
power. See Note 6.
V
RX-IDLE-DET-DIFFp-p
= 2 × |V
RX-D+
–V
RX-D–
|.
Measured at the package pins of the receiver
An unexpected electrical idle (V
RX-DIFFp-p
<
V
RX-IDLE-DET-DIFFp-p
) must be recognized no
longer than T
RX-IDLE-DET-DIFF-ENTERING
to signal
an unexpected idle condition.
RL
RX-DIFF
15
—
—
dB
RL
RX-CM
Z
RX-DIFF-DC
Z
RX-DC
Z
RX-HIGH-IMP-DC
6
80
40
200 k
—
100
50
—
—
120
60
—
dB
Ω
Ω
Ω
V
RX-IDLE-DET-DIFFp-p
T
RX-IDLE-DET-DIFF-
ENTERTIME
65
—
—
—
175
10
mV
ms
MPC8548E PowerQUICC™ III Integrated Processor Hardware Specifications, Rev. 6
74
Freescale Semiconductor
FREESCALE [ FREESCALE SEMICONDUCTOR, INC ]
