Datasheet 61
Intel
®
Celeron
®
Processor up to 1.10 GHz
3.4.5 Reading Overshoot/Undershoot Specification Tables (FC-PGA/
FC-PGA2 Packages)
The overshoot/undershoot specification for the FC-PGA/FC-PGA2 packages processor is not a
simple single value. Instead, many factors are needed to determine the over/undershoot
specification. In addition to the magnitude of the overshoot, the following parameters must also be
known: the junction temperature the processor will be operating, 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, the following must be done:
1. Determine the signal group that particular signal falls into. If the signal is an AGTL+ signal
operating with a 66 MHz system bus, use Table 38 (66 MHz AGTL+ signal group). If the
signal is a CMOS signal, use Table 39 (33 MHz CMOS signal group).
2. Determine the maximum junction temperature (Tj) for the range of processors that the system
will support (80
o
C or 90
o
C).
3. Determine the Magnitude of the overshoot (relative to V
SS)
4. Determine the Activity Factor (how often does this overshoot occur?)
5. From the appropriate Specification table, read off the Maximum Pulse Duration (in ns)
allowed.
6. 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.
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.
Table 37 shows an example of how the maximum pulse duration is determined for a given
waveform.
NOTES:
1. Corresponding Maximum Pulse Duration Specification – 3.2 ns
2. Pulse Duration (measured) – 2.0 ns
Given the above parameters, and using Table 38 (90
o
C/AF=0.1 column) the maximum allowed
pulse duration is 3.2 ns. Since the measured pulse duration is 2.0ns, this particular overshoot event
passes the overshoot specifications, although this doesn't guarantee that the combined overshoot/
undershoot events meet the specifications.
Table 37. Example Platform Information
Required Information Maximum Platform Support Notes
FSB Signal Group 66 MHz AGTL+
Max Tj 90 °C
Overshoot Magnitude 2.13V Measured Value
Activity Factor (AF) 0.1
Measured overshoot occurs on
average every 20 clocks
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