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