Intel III 450 MHz 80525PY450512 Data Sheet
Product codes
80525PY450512
Datasheet
43
Signal Quality Specifications
3.2.4
Reading Overshoot/Undershoot Specification Tables
The overshoot/undershoot specification for the Pentium III processor is not a simple single value.
Instead, many factors are needed to determine what the over/undershoot specification is. In
addition to the magnitude of the overshoot, the following parameters must also be known: the
width of the overshoot (as measured above 1.635 V) and the Activity Factor (AF). To determine
the allowed overshoot for a particular overshoot event, you must do the following:
Instead, many factors are needed to determine what the over/undershoot specification is. In
addition to the magnitude of the overshoot, the following parameters must also be known: the
width of the overshoot (as measured above 1.635 V) and the Activity Factor (AF). To determine
the allowed overshoot for a particular overshoot event, you must do the following:
1. Determine the signal group that particular signal falls into. If the signal is an AGTL+ signal
operating with a 100 MHz system bus, use
. If the signal is an AGTL+ signal
operating with a 133 MHz system bus, use
. If the signal is a CMOS signal, use
2. Determine the Magnitude of the overshoot (relative to V
SS
).
3. Determine the Activity Factor (how often does this overshoot occur?).
4. From the appropriate Specification table, read off the Maximum Pulse Duration (in ns)
allowed.
5. Compare the specified Maximum Pulse Duration to the signal being measured. If the Pulse
Duration measured is less than the Pulse Duration shown in the table, then the signal meets the
specifications.
specifications.
The above procedure is similar for undershoots after the undershoot waveform has been converted
to look like an overshoot. Undershoot events must be analyzed separately from Overshoot events
as they are mutually exclusive.
to look like an overshoot. Undershoot events must be analyzed separately from Overshoot events
as they are mutually exclusive.
Below is an example showing how the maximum pulse duration is determined for a given
waveform and how it relates to a measured value:
waveform and how it relates to a measured value:
Platform Information:
•
Signal Group = 133 MHz AGTL+
•
Overshoot Magnitude (measured) = 2.3 V
•
Pulse Duration (measured) = 1.6 ns
•
Activity Factor (measured) = 0.1
Corresponding Maximum Pulse Duration Specification = 1.9 ns
Given the above parameters and using
(AF = 0.1 column), the maximum allowed pulse
duration is 1.9 ns. Since the measured pulse duration is 1.6 ns, this particular overshoot event
passes the overshoot specifications, although this doesn't guarantee that the combined overshoot/
undershoot events meet the specifications.
passes the overshoot specifications, although this doesn't guarantee that the combined overshoot/
undershoot events meet the specifications.