MPC8308CVMAFDA datasheet(33/88 Pages) FREESCALE

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MPC8308 PowerQUICC II Pro Processor Hardware Specification, Rev. 0

Freescale Semiconductor

High-Speed Serial Interfaces (HSSI)

Figure 24. Differential Measurement Points for Rise and Fall Time

Figure 25. Single-Ended Measurement Points for Rise and Fall Time Matching

The other detailed AC requirements of the SerDes reference clocks is defined by each interface protocol

based on application usage. For detailed information, see the following sections:

•

Section 11.2, “AC Requirements for PCI Express SerDes Clocks”

Rising edge rate (SD_REF_CLK) to falling edge rate

(SD_REF_CLK) matching

Rise-Fall

Matching

—20

1, 4

Notes:

1. Measurement taken from single ended waveform.

2. Measurement taken from differential waveform.

3. Measured from –200 mV to +200 mV on the differential waveform (derived from SD_REF_CLK minus SD_REF_CLK). The

signal must be monotonic through the measurement region for rise and fall time. The 400 mV measurement window is centered

on the differential zero crossing (Figure 24).

4. Matching applies to rising edge rate for SD_REF_CLK and falling edge rate for SD_REF_CLK. It is measured using a 200

mV window centered on the median cross point where SD_REF_CLK rising meets SD_REF_CLK falling. The median cross

point is used to calculate the voltage thresholds the oscilloscope is to use for the edge rate calculations. The Rise Edge Rate

of SD_REF_CLK should be compared to the Fall Edge Rate of SD_REF_CLK, the maximum allowed difference should not

exceed 20% of the slowest edge rate (See Figure 25).

Table 32. SerDes Reference Clock AC Parameters (continued)

At recommended operating conditions with XCOREVDD= 1.0V ± 5%

Parameter

Symbol

Min

Max

Unit

Notes

VIH = +200

VIL = -200 mV

0.0 V

SD_REF_CLK

minus

SD_REF_CLK

MPC8308CVMAFDA Datasheet(PDF) 33 Page - Freescale Semiconductor, Inc