Electrical Characteristics
Table 4-9. Differential Receiver (RX) DC Input Specifications (Sheet 2 of 2)
Symbol
Parameter
Min
Nom
Max
Units Comments
ZRX- DC
DC Input Impedance
40
50
60
W
W
Required RX D+ as well as
D-DC impedance (50 Ω+/-20%
tolerance). See Notes 1 and 3.
ZRX- HIGH-IMP-
Powered Down DC
Input Impedance
200 k
65
Required RX D+ as well as
D-DC impedance when the
receiver terminations do not
have power. See Note 4.
DC
VRX-IDLE-DET-
Electrical Idle Detect
Threshold
175
mV
VRX-IDLE-DET-DIFFp-p =2*|VRX-D+
- VRX-D-
|
DIFFp-p
Measured at the package pins
of the Receiver.
NOTES:
1. Specified at the measurement point and measured over any 250 consecutive UIs. The test load in Figure 4-2
should be used as the RX device when taking measurements (also refer to the Receiver Compliance Eye
Diagram as shown in Figure 4-3). If the clocks to the RX and TX are not derived from the same clock chip the
TX UI must be used as a reference for the eye diagram.
2. The receiver input impedance shall result in a differential return loss greater than or equal to 15 dB with the
D+ line biased to 300 mV and the D- line biased to -300 mV and a common mode return loss greater than or
equal to 6 dB (no bias required) 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 for is
50 Ω to ground for both the D+ and D- line (i.e., as measured by a Vector Network Analyzer with 50 Ω probes
- see Figure 4-2). Note: that the series capacitors CTX is optional for the return loss measurement.
3. Impedance during all LTSSM states. When transiting from a Fundamental Reset to Detect (the initial state of
the LTSSM) there is a 5 ms transition time before receiver termination values must be met on all
unconfigured Lanes of a Port.
The RX DC Common Mode Impedance that exists when no power is present or Fundamental Reset
is asserted. This helps ensure that the Receiver Detect circuit will not falsely assume a receiver is
powered on when it is not. This term must be measured at 300 mV above the RX ground.
Intel® 6702PXH 64-bit PCI Hub Datasheet
161
INTEL [ INTEL ]
