Datasheet

XIO2001
www.ti.com SCPS212G –MAY 2009–REVISED DECEMBER 2012
PCI Express Differential Transmitter Output Ranges (continued)
PARAMETER TERMINALS MIN NOM MAX UNIT COMMENTS
V
TX-CM-AC-P
(7)
TXP, TXN 20 mV
T
X
AC common mode voltage
I
TX-SHORT
The total current transmitter can supply when shorted to
TXP, TXN 90 mA
Transmitter short-circuit current limit ground.
V
TX-DC-CM
The allowed DC common-mode voltage at the transmitter
TXP, TXN 0 3.6 V
Transmitter DC common-mode voltage pins under any conditions.
|VTX-CM-DC – VTX-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]
Absolute delta of DC common mode TXP, TXN 0 100 mV
V
TX-CM-Idle-DC
= DC
(avg)
of |V
TXP
+ V
TXN
|/2 [during electrical
voltage during L0 and electrical idle
idle]
V
TX-CM-DC-LINE-DELTA
|V
TXP-CM-DC
– V
TXN-CM-DC
| ≤25 mV when
Absolute delta of DC common mode TXP, TXN 0 25 mV V
TXP-CM-DC
= DC
(avg)
of |V
TXP
| [during L0]
voltage between P and N V
TXN-CM-DC
= DC
(avg)
of |V
TXN
| [during L0]
V
TX-IDLE-DIFF-AC-p
Electrical idle differential peak output TXP, TXN 0 20 mV V
TX-IDLE-DIFFp
= |V
TXP-Idle
– V
TXN-Idle
| ≤ 20 mV
voltage
V
TX-RCV-DETECT
The total amount of voltage change that a transmitter can
The amount of voltage change allowed TXP, TXN 600 mV apply to sense whether a low impedance receiver is
during receiver detection present.
T
TX-IDLE-MIN
TXP, TXN 20 ns Minimum time a transmitter must be in electrical idle.
Minimum time spent in electrical idle
After sending the required number of EIOSs, the
T
TX-IDLE-SET-TO-IDLE
transmitter must meet all electrical idle specifications
Maximum time to transition to a valid TXP, TXN 8 ns
within this time. This is measured from the end of the last
electrical idle after sending an EIOS
EIOS to the transmitter in electrical idle.
T
TX-IDLE-TO-DIFF-DATA
Maximum time to transistion to valid diff signaling after
Maximum time to transition to a valid diff TXP, TXN 8 ns leaving electrical idle. This is considered a debounce time
signaling after leaving electrical idle to the Tx.
All transmitters shall be AC coupled. The AC coupling is
C
TX
TXP, TXN 75 200 nF required either within the media or within the transmitting
AC coupling capacitor
component itself.
(7) Measurement is made over at least 10 UI.
7.5 PCI Express Differential Receiver Input Ranges
PARAMETER TERMINALS MIN NOM MAX UNIT COMMENTS
UI
(1)
Each UI is 400 ps ±300 ppm. UI does not account for
RXP, RXN 399.88 400.12 ps
Unit interval SSC dictated variations.
V
RX-DIFF-PP-CC
(2)
RXP, RXN 0.175 1.200 V V
RX-DIFFp-p
= 2*|V
RXP
– V
RXN
|
Differential input peak-to-peak voltage
The maximum interconnect media and transmitter jitter
T
RX-EYE
(2) (3)
RXP, RXN 0.4 UI that can be tolerated by the receiver is derived as T
RX-
Minimum receiver eye width
MAX-JITTER
= 1 – T
RX-EYE
= 0.6 UI
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
(2) (3)
recovered TX UI. A recovered TX UI is calculated over
Maximum time between the jitter median RXP, RXN 0.3 UI 3500 consecutive UIs of sample data. Jitter is
and maximum deviation from the median measured using all edges of the 250 consecutive UIs
in the center of the 3500 UIs used for calculating the
TX UI.
BW
RX-PLL-HI
(4)
RXP, RXN 22 MHz Second order PLL jitter transfer bounding function.
Maximum Rx PLL bandwidth
(1) No test load is necessarily associated with this value.
(2) Specified at the measurement point and measured over any 250 consecutive UIs. A test load must be used as the RX device when
taking measurements. If the clocks to the RX and TX are not derived from the same reference clock, then the TX UI recovered from
3500 consecutive UIs is used as a reference for the eye diagram.
(3) A TRX-EYE = 0.40 UI provides for a total sum of 0.60 UI deterministic and random jitter budget for the transmitter and interconnect
collected any 250 consecutive UIs. The TRX-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 UI 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. If the clocks to the RX and TX are not derived
from the same reference clock, then the TX UI recovered from 3500 consecutive UIs must be used as the reference for the eye
diagram.
(4) A single PLL bandwidth and peaking value of 1.5 to 22 MHz and 3 dB are defined.
Copyright © 2009–2012, Texas Instruments Incorporated Electrical Characteristics 117
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