Electrical Characteristics
4.3
Timing Specifications
4.3.1
PCI Express Interface Timing
4.3.1.1
Differential Transmitter (TX) Output Specifications
Table 4-16 defines the specifications of parameters for the differential output at all transmitters
(TXs). The parameters are specified at the component pins.
Table 4-16. Differential Transmitter (TX) Output Specifications
Symbol
Parameter
Min
Nom
Max
Units Comments
UI
Unit Interval
399.88 400 400.12
ps
UI
UI
Each UI is 400 ps +/-300 ppm.
UI does not account for SSC
dictated variations.
See Note 1.
TTX-EYE
Minimum TX Eye Width
0.70
The maximum transmitter jitter
can be derived as TTX-MAX-
JITTER = 1 - TTX-EYE = .3 UI
See Notes 2 and 3.
TTX-EYE-
Maximum time between
the jitter median and
maximum deviation for
the median
0.15
Jitter is defined as the
measurement variation of the
MEDIAN-to-MAX-
JITTER
crossing points (VTX-DIFFp-p
=
0V) in relation to an appropriate
average TX UI.
See Notes 2 and 3.
TTX-RISE, TTX- D+/D- TX Output Rise/
0.125
50
UI
UI
UI
See Notes 2 and 4.
Fall Time
FALL
TTX-IDLE-MIN
Minimum time spent in
Electrical Idle
Minimum time a transmitter
must be in Electrical Idle.
TTX-IDLE-SET- Maximum time to
20
After sending an Electrical Idle
ordered-set, the transmitter
must meet all Electrical Idle
specifications within this time.
transition to a valid
Electrical Idle after
sending an Electrical
Idle ordered-set
TO-IDLE
TTX-IDLE-RCV- Maximum time spent in
100
ms
ps
Maximum time spent in
Electrical Idle before initiating a
receiver detect sequence.
Electrical Idle before
DETECT-
initiating a receiver
MAX
detect sequence.
LTX-SKEW
Lane-to-Lane Output
Skew
500 +
2UI
Static skew between any two
Transmitter Lanes within a
single Link.
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 Figure 4-2
and measured over any 250 consecutive TX UIs. (Also refer to the Transmitter Compliance Eye Diagram as
shown in Figure 4-1.)
3. A TTX-EYE = 0.70 UI provides for a total sum of deterministic and random jitter budget of TTX-JITTER-MAX
=
0.30 UI for the transmitter collected over any 250 consecutive TX UIs. The TTX-EYE-MEDIAN-to-MAX-JITTER
specification ensures a jitter distribution in which the median and the maximum deviation from the median is
less than half of the total 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.
4. Measured between 20-80% at Transmitter package pins into a test load as shown in Figure 4-2 for both
V
TX-D+ and VTX-D-.
168
Intel® 6702PXH 64-bit PCI Hub Datasheet
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