IBM Intel Xeon E5-2637 49Y8125 User Manual

184

Intel® Xeon® Processor E5-1600/E5-2600/E5-4600 Product Families

Datasheet Volume One

Signal Quality specifications for Differential Intel® QuickPath Interconnect Signals are 

included as part of the Intel QuickPath Interconnect signal quality specifications. 

Various scenarios have been simulated to generate a set of layout guidelines which are 
available in the appropriate Platform Design Guide (PDG).

Overshoot/Undershoot and Ringback specifications for BCLK{0/1}_D[N/P] are found in 

. Overshoot/Undershoot and Ringback specifications for the DDR3 Reference 

Clocks are specified by the DIMM.

Overshoot (or undershoot) is the absolute value of the maximum voltage above or 
below V

SS,

. The overshoot/undershoot specifications limit transitions 

beyond V

CCD

 or V

SS

 due to the fast signal edge rates. The processor can be damaged 

by single and/or repeated overshoot or undershoot events on any input, output, or I/O 
buffer if the charge is large enough (that is, if the over/undershoot is great enough). 

Determining the impact of an overshoot/undershoot condition requires knowledge of 

the magnitude, the pulse direction, and the activity factor (AF). Permanent damage to 
the processor is the likely result of excessive overshoot/undershoot.

Baseboard designs which meet signal integrity and timing requirements and which do 

not exceed the maximum overshoot or undershoot limits listed in 

 will insure 

reliable IO performance for the lifetime of the processor.

1.

These specifications are measured at the processor pad.

2.

Refer to 

 for description of allowable Overshoot/Undershoot magnitude and duration.

3.

TCH is the minimum high pulse width duration.

4.

For PWRGOOD DC specifications see 

.

Overshoot/Undershoot magnitude describes the maximum potential difference between 

a signal and its voltage reference level. For the processor, both overshoot and 

undershoot magnitude are referenced to V

SS

. It is important to note that the overshoot 

and undershoot conditions are separate and their impact must be determined 

independently.

The pulse magnitude and duration, and activity factor must be used to determine if the 

overshoot/undershoot pulse is within specifications.

Intel QuickPath Interconnect

-0.2 * VTT

1.2 * VTT

39 ps

15 ps

1,2

DDR3

-0.2 * V

CCD

1.2 * V

CCD

0.25*T

CH

0.1*T

CH

1,2,3

System Reference Clock (BCLK{0/1})

-0.3V

1.15V

N/A

N/A

1,2

PWRGOOD Signal

-0.420V

VTT + 0.28

N/A

N/A

4