Intel 9150N NE80567KE025015 User Manual
Product codes
NE80567KE025015
Intel
®
Itanium
®
Processor 9300 Series Datasheet
31
Electrical Specifications
2.6.3
Overshoot and Undershoot Guidelines
Overshoot (or undershoot) is the value of the maximum voltage above or below VSS.
The overshoot and undershoot specifications limit transitions beyond VCCIO or VSS 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 overshoot or undershoot is great enough). Determining the
impact of an overshoot or undershoot condition requires knowledge of the magnitude,
the pulse duration, and the activity factor (AF). Permanent damage to the processor is
the likely result of excessive overshoot or undershoot.
The overshoot and undershoot specifications limit transitions beyond VCCIO or VSS 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 overshoot or undershoot is great enough). Determining the
impact of an overshoot or undershoot condition requires knowledge of the magnitude,
the pulse duration, and the activity factor (AF). Permanent damage to the processor is
the likely result of excessive overshoot or undershoot.
2.6.3.1
Overshoot/Undershoot Magnitude, Pulse Duration and Activity Factor
Magnitude describes the maximum potential difference between a signal and its voltage
1 = reference level. For the Intel® Itanium® processor 9300 series, both are referenced to VSS. It is important
to note that overshoot and undershoot conditions are separate and their impact must be determined
independently.
Pulse duration describes the total amount of time that an overshoot or undershoot
event exceeds the overshoot or undershoot reference voltage. Activity factor (AF)
describes the frequency of overshoot or undershoot occurrence relative to a clock.
Since the highest frequency of assertion of a single-ended signal is every other clock,
an AF = 1 indicates that the specific overshoot or undershoot waveform occurs every
other clock cycle. Thus, an AF = 0.01 indicates that the specific overshoot or
undershoot waveform occurs one time in every 200 clock cycles. The highest frequency
of assertion of any differential signal is every active edge of its associated clock (not
the reference clock). So, an AF = 1 indicates that the specific overshoot or undershoot
waveform occurs every cycle.
event exceeds the overshoot or undershoot reference voltage. Activity factor (AF)
describes the frequency of overshoot or undershoot occurrence relative to a clock.
Since the highest frequency of assertion of a single-ended signal is every other clock,
an AF = 1 indicates that the specific overshoot or undershoot waveform occurs every
other clock cycle. Thus, an AF = 0.01 indicates that the specific overshoot or
undershoot waveform occurs one time in every 200 clock cycles. The highest frequency
of assertion of any differential signal is every active edge of its associated clock (not
the reference clock). So, an AF = 1 indicates that the specific overshoot or undershoot
waveform occurs every cycle.
2.6.3.2
Overshoot/Undershoot Specifications
The overshoot and undershoot specifications listed in the following table specify the
allowable overshoot or undershoot for a single overshoot or undershoot event.
allowable overshoot or undershoot for a single overshoot or undershoot event.
specifies the maximum overshoot and undershoot for the processor for both
the single ended and the differential signalling pins. The overshoot and undershoot val-
ues assume an activity factor of 100% and a pulse width of 25% over the signal pulse
width. The table also includes the absolute maximum and minimum values beyond
which the processor is not guaranteed to operate properly. These values assume a
pulse width of 1% and an activity factor of 100%.
ues assume an activity factor of 100% and a pulse width of 25% over the signal pulse
width. The table also includes the absolute maximum and minimum values beyond
which the processor is not guaranteed to operate properly. These values assume a
pulse width of 1% and an activity factor of 100%.
Table 2-14. Overshoot and Undershoot Specifications For Differential
Intel QuickPath Interconnect and Intel® SMI and Single-Ended Signals
Symbol
Parameter
Min
Max
Unit
V
MAX-OS-SE_
Overshoot for single-ended signals
1.45
V
V
MIN-US-SE
Undershoot for single-ended signals
-0.247
V
V
ABSMAX-OS-SE
Absolute Max for single-ended signals
1.6
V
V
ABSMIN-US-SE
Absolute Min for single-ended signals
-0.425
V
V
MAX-OS-DIFF
Overshoot for Intel QPI and Intel SMI
signals
1.54
V
V
MAX-US-DIFF
Undershoot for Intel QPI and Intel SMI
signals
-0.337
V
V
ABSMAX-OS-DIFF
Absolute Max for Intel QPI and Intel SMI
signals
1.7
V
V
ABSMAX-US-DIFF
Absolute Min for Intel QPI and Intel SMI
signals
-0.525
V