Specifications

XIO3130
SLLS693F–MAY 2007 –REVISED JANUARY 2010 www.ti.com
PCI Express Differential Transmitter Output Ranges (continued)
PARAMETER TERMINALS MIN NOM MAX UNIT COMMENTS
Maximum time to meet all TX specifications when
T
TX-IDLE-to-DIFF-DATA
transitioning from electrical idle to sending
Maximum time to transition to valid PETP,
20 UI differential data. This value is considered a
TX specifications after leaving an PETN
de-bounce time for the TX to meet all TX
electrical idle condition
specifications after leaving electrical idle.
RL
TX-DIFF
PETP, Measured over 50 MHz to 1.25 GHz.
10 dB
Differential return loss PETN See
(5)
RL
TX-CM
PETP, Measured over 50 MHz to 1.25 GHz.
6 dB
Common mode return loss PETN See
(5)
Z
TX-DIFF-DC
PETP,
80 100 120 Ω TX DC differential mode low impedance
DC differential TX impedance PETN
Z
TX-DC
PETP, Required TX-D+ as well as TX-D– DC impedance
40 Ω
Transmitter DC impedance PETN during all states
C
TX
PETP, All transmitters are AC-coupled and capacitors are
75 200 nF
AC coupling capacitor PETN required on the PWB.
(5) The transmitter input impedance results in a differential return loss greater than or equal to 12 dB and a common mode return loss
greater than or equal to 6 dB 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 is 50 Ω to ground for both the P and N lines. Note that the series
capacitors CTX is optional for the return loss measurement.
6.4 PCI Express Differential Receiver Input Ranges
PARAMETER TERMINALS MIN NOM MAX UNIT COMMENTS
V
RX-DIFFp-p
PERP, V
RX-DIFFp-p
= 2*|V
RX-D+
– V
RX-D–
|
Differential input peak-to-peak 0.175 1.2 V
PERN See
(1)
voltage
The maximum interconnect media and transmitter
T
RX-EYE
jitter that can be tolerated by the Receiver is
PERP, PERN 0.4 UI
Minimum receiver eye width derived as T
RX-MAX- JITTER
= 1 - T
RX-EYE
= .6 UI
See
(1) (2) (3)
Jitter is defined as the measurement variation of
the crossing points (V
RX-DIFFp-p
= 0 V) in relation to
T
RX-EYE-MEDIAN-to-MAX-JITTER
recovered TX UI. A recovered TX UI is calculated
Maximum time between the jitter PERP, over 3500 consecutive unit intervals of sample
0.3 UI
median and maximum deviation PERN data. Jitter is measured using all edges of the 250
from the median. consecutive UI in the center of the 3500 UI used
for calculating the TX UI.
See
(1) (2)
V
RX-CM-ACp
= RMS( |V
RX-D+
+ V
RX-D–
| / 2 –
V
RX-CM-ACp
PERP, V
RX-CM-DC)
AC peak common mode input 150 mV
PERN V
RX-CM-DC
= DC
(avg)
of |V
RX-D+
+ V
RX-D-
| / 2
voltage
See
(1)
(1) Specified at the measurement point and measured using the clock recovery function specified in PCI Express™ Base Specification
Revision 1.1, Section 4.3.3.2. The test load in Figure 4-25 should be used as the RX device when taking measurements (also refer to
the Receiver compliance eye diagram shown in Figure 4-26 of the specification). If the clocks to the RX and TX are not derived from the
same reference clock, the TX UI recovered using the clock recovery function specified in Section 4.3.3.2 must be used as a reference
for the eye diagram.
(2) The T
RX-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 0.64. 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. The RX
UI recovered using the clock recovery function specified in Section 4.3.3.2 must be used as the reference for the eye diagram. This
parameter is measured with the equivalent of a zero jitter reference clock. The T
RX-EYE
measurement is to be met at the target bit error
rate. The T
RX-EYE-MEDIAN-to-MAX-JITTER
specification is to be met using the compliance pattern at a sample size of 1,000,000 UI.
(3) See the PCI Express Jitter and BER white paper for more details on the Rx-Eye measurement.
136 Electrical Characteristics Copyright © 2007–2010, Texas Instruments Incorporated
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