MPC8569E datasheet(89/127 Pages) FREESCALE

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PCI Express

MPC8569E PowerQUICC III Integrated Processor Hardware Specifications, Rev. 1

Freescale Semiconductor

The following table defines the AC specifications for the PCI Express (2.5 Gb/s) differential input at all receivers (RXs). The

parameters are specified at the component pins. The AC timing specifications do not include RefClk jitter.

Table 52. PCI Express (2.5 Gb/s) Differential Receiver (RX) Input AC Specifications

At recommended operating conditions with ScoreVDD = 1.0 V ± 3%. and 1.1 V ± 3%

Parameter

Symbol

Min

Typ

Max

Unit

Comments

Unit interval

399.88

400.00

400.12

Each UI is 400 ps ± 300 ppm. UI does not account for

spread spectrum clock dictated variations. See Note 1.

Minimum

receiver eye

width

TRX-EYE

0.4

—

The maximum interconnect media and transmitter jitter

that can be tolerated by the receiver can be derived as

TRX-MAX-JITTER = 1 – TRX-EYE = 0.6 UI. See Notes 2 and 3.

Maximum time

between the

jitter median

and maximum

deviation from

the median.

TRX-EYE-MEDIA

N-to-MAX-JITTER

—

0.3

Jitter is defined as the measurement variation of the

crossing points (VRX-DIFFp-p = 0 V) in relation to a

recovered TX UI. A recovered TX UI is calculated over

3500 consecutive unit intervals of sample data. Jitter is

measured using all edges of the 250 consecutive UI in the

center of the 3500 UI used for calculating the TX UI.

See Notes 2, 3, and 4.

Notes:

1. No test load is necessarily associated with this value.

2. Specified at the measurement point and measured over any 250 consecutive UIs. The test load in Figure 46 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, the

TX UI recovered from 3500 consecutive UI must be 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, the TX UI recovered from 3500 consecutive UI must

be used as the reference for the eye diagram.

4. It is recommended that the recovered TX UI is calculated using all edges in the 3500 consecutive UI interval with a fit algorithm

using a minimization merit function. Least squares and median deviation fits have worked well with experimental and

simulated data.

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