mpc8536e Freescale Semiconductor, Inc, mpc8536e Datasheet - Page 98

• Manufacturer Part Number: mpc8536e
• Description: Mpc8536e Powerquicctm Iii Integrated Processor Hardware Specifications
• Manufacturer: Freescale Semiconductor, Inc

High-Speed Serial Interfaces
2.20.2.4 AC Requirements for SerDes Reference Clocks
The clock driver selected should provide a high quality reference clock with low phase noise and cycle-to-cycle jitter. Phase
noise less than 100KHz can be tracked by the PLL and data recovery loops and is less of a problem. Phase noise above 15MHz
is filtered by the PLL. The most problematic phase noise occurs in the 1-15MHz range. The source impedance of the clock
driver should be 50 ohms to match the transmission line and reduce reflections which are a source of noise to the system.
Table 69
98
At recommended operating conditions with XV
Rising Edge Rate
Falling Edge Rate
Differential Input High Voltage
Differential Input Low Voltage
Rising edge rate (SDn_REF_CLK) to falling edge rate
(SDn_REF_CLK) matching
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 SDn_REF_CLK minus SDn_REF_CLK). The
4. Matching applies to rising edge rate for SDn_REF_CLK and falling edge rate for SDn_REF_CLK. It is measured using a 200
V
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. See
mV window centered on the median cross point where SDn_REF_CLK rising meets SDn_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 SDn_REF_CLK should be compared to the Fall Edge Rate of SDn_REF_CLK, the maximum allowed difference should not
exceed 20% of the slowest edge rate. See
SD n _REF_CL
K
IL
V
IH
= –200 mV
describes some AC parameters common to SGMII and PCI Express protocols.
=
0.0 V
+200
minus
MPC8536E PowerQUICC™ III Integrated Processor Hardware Specifications, Rev. 2
Figure 66. Differential Measurement Points for Rise and Fall Time
Parameter
Table 69. SerDes Reference Clock Common AC Parameters
DD_SRDS1
Figure
Figure
or XV
67.
DD_SRDS2
66.
= 1.0V ± 5%.
Rise Edge Rate
Fall Edge Rate
Matching
Rise-Fall
Symbol
V
V
IH
IL
+200
Min
1.0
1.0
—
—
–200
Max
4.0
4.0
—
20
Freescale Semiconductor
V/ns
V/ns
Unit
mV
mV
%
Notes
2, 3
2, 3
1, 4
2
2