Specifications

XIO3130
www.ti.com SLLS693F–MAY 2007–REVISED JANUARY 2010
6.3 PCI Express Differential Transmitter Output Ranges
PARAMETER TERMINALS MIN NOM MAX UNIT COMMENTS
UI PETP, Each UI is 400 ps ±300 ppm. UI does not account
399.88 400 400.12 ps
Unit interval PETN for SSC dictated variations.See
(1)
V
TX-DIFFp-p
PETP, V
TX-DIFFp-p
= 2*|V
TXP
– V
TXN
|.
Differential peak-to-peak output 0.8 1.2 V
PETN See
(2)
voltage
This value is the ratio of the V
TX-DIFFp-p
of the
V
TX-DE-RATIO
PETP, second and following bits after a transition divided
De-emphasized differential output –3 –3.5 –4.0 dB
PETN by the V
TX-DIFFp-p
of the first bit after a transition.
voltage (ratio)
See
(2)
The maximum transmitter jitter can be derived as
T
TX-EYE
PETP,
0.75 UI T
TXMAX- JITTER
= 1 – T
TX-EYE
= 0.25 UI.
Minimum TX eye width PETN
See
(2) (3)
Jitter is defined as the measurement variation of
the crossing points (V
TX-DIFFp-p
= 0 V) in relation to
T
TX-EYE-MEDIAN-to-MAX-JITTER
recovered TX UI. A recovered TX UI is calculated
Maximum time between the jitter PETP,
0.125 UI over 3500 consecutive UIs of sample data. Jitter is
median and maximum deviation PETN
measured using all edges of the 250 consecutive
from the median
UIs in the center of the 3500 UIs that are used for
calculating the TX UI. See
(2) (3)
T
TX-RISE,
PETP,
T
TX-FALL
0.125 UI See
(2) (4)
PETN
Differential TX output rise/fall time
V
TX-CM-ACp
V
TX-CM-ACp
= RMS(|V
TXP
+ V
TXN
|/2 – V
TX-CM-DC
)
PETP,
RMS ac peak common mode output 20 mV V
TX-CM-DC
= DC
(avg)
of |V
TXP
+ V
TXN
|/2
PETN
voltage See
(2)
|V
TX-CM-DC
– V
TX-CM-IDLE-DC
| ≤ 100 mV
V
TX-CM-DC-ACTIVE-IDLE-DELTA
V
TX-CM-DC
= DC
(avg)
of |V
TXP
+ V
TXN
|/2 [during L0]
PETP,
Absolute delta of DC common mode 0 100 mV V
TX-CM-IDLE-DC
= DC
(avg)
of |V
TXP
+ V
TXN
|/2 [during
PETN
voltage during L0 and electrical idle. electrical idle]
See
(2)
|V
TXP-CM-DC
– V
TXN-CM-DC
| ≤ 25 mV when
V
TX-CM-DC-LINE-DELTA
PETP, V
TXP-CM-DC
= DC
(avg)
of |V
TXP
|
Absolute delta of DC common mode 0 25 mV
PETN V
TXN-CM-DC
= DC
(avg)
of |V
TXN
|
voltage between P and N
See
(2)
V
TX-IDLE-DIFFp
PETP, V
TX-IDLE-DIFFp
= |V
TXP-IDLE
– V
TXN-IDLE
| ≤ 20 mV
Electrical idle differential peak output 0 20 mV
PETN See
(2)
voltage
V
TX-RCV-DETECT
The total amount of voltage change that a
PETP,
The amount of voltage change 600 mV transmitter can apply to sense whether a low
PETN
allowed during receiver detection impedance receiver is present.
V
TX-DC-CM
PETP, The allowed DC common mode voltage under any
0 3.6 V
The TX DC common mode voltage PETN condition
I
TX-SHORT
PETP, The total current that the transmitter can provide
90 mA
TX short circuit current limit PETN when shorted to its ground.
Minimum time that a transmitter must be in
T
TX-IDLE-MIN
PETP, electrical Idle. The receiver uses this value to start
50 UI
Minimum time spent in electrical idle PETN looking for an electrical idle exit after successfully
receiving an electrical idle ordered set.
After sending an electrical idle ordered set, the
T
TX-IDLE-SET-to-IDLE
transmitter must meet all electrical idle
Maximum time to transition to a valid PETP,
20 UI specifications within this time. This is considered a
electrical idle after sending an PETN
de-bounce time for the transmitter to meet
electrical idle ordered set
electrical idle after transitioning from L0.
(1) No test load is necessarily associated with this value.
(2) Specified at the measurement point into a timing and voltage compliance test load and measured over any 250 consecutive TX UIs.
(3) A T
TX-EYE
= 0.75 UI provides for a total sum of deterministic and random jitter budget of T
TX-JITTER-MAX
= 0.25 UI for the transmitter
collected over any 250 consecutive TX UIs. The T
TX-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
must 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% and 80% at transmitter package terminals into a test load for both VTX-D+ and VTX-D–.
Copyright © 2007–2010, Texas Instruments Incorporated Electrical Characteristics 135
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