Itanium Itanium; Overshoot And Undershoot Guidelines - Intel BX80569Q9550 - Core 2 Quad 2.83 GHz Processor Datasheet

2.6.5

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.
2.6.5.1 Overshoot/Undershoot Magnitude, Pulse Duration and Activity Factor
Magnitude describes the maximum potential difference between a signal and its voltage
reference level. For the Intel
Processor 9500 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.
2.6.5.2 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.
Table 2-25
Processor 9300 Series, while
shoot for the Intel
single ended and the differential signalling pins. The overshoot and undershoot values
assume an activity factor of 100% and a pulse width of 25% over the signal pulse
width. The tables also include 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%.
2.6.5.2.1 Overshoot and Undershoot Specifications for the Intel
9300 Series
Table 2-25. Overshoot and Undershoot Specifications For Differential
®
Intel QuickPath Interconnect and Intel
for the Intel
Symbol
V
MAX-OS-SE
V
MIN-US-SE
V
ABSMAX-OS-SE
V
ABSMIN-US-SE
52
®
Itanium
specifies the maximum overshoot and undershoot for the Intel
Table 2-26
® Itanium ® Processor 9500 Series, respectively, identifying both the
® ®
Itanium Processor 9300 Series (Sheet 1 of 2)
Parameter
Overshoot for single-ended signals
Undershoot for single-ended signals
Absolute Max for single-ended signals
Absolute Min for single-ended signals
®
Processor 9300 Series and Intel
specifies the maximum overshoot and under-
®
SMI and Single-Ended Signals
Min
-0.247
-0.425
® ®
Intel Itanium Processor 9300 Series and 9500 Series Datasheet
Electrical Specifications
® ®
Itanium
®
Itanium
® ®
Itanium Processor
Max Unit
1.45 V
V
1.6 V
V
®