®
MOBILE PENTIUM PROCESSOR WITH MMX™ TECHNOLOGY
4.4.3. CLOCK SIGNAL MEASUREMENT
OVERSHOOT THRESHOLD DURATION
METHODOLOGY: The waveform of the clock
signals should be measured at the bottom side of
the processor pins using an oscilloscope with a 3
dB bandwidth of at least 20 MHz (100 MS/s digital
sampling rate). There should be a short isolation
ground lead attached to a processor pin on the
bottom side of the board. An 1 MOhm probe with
loading of less than 1 pF (e.g., Tektronics 6243 or
SPECIFICATION: A snapshot of the clock signal
should be taken at 500 mV/div and 500 pS/div.
Adjust the vertical position and horizontal offset
position to view the threshold duration.
The
overshoot threshold duration is defined as the sum
of all time during which the clock signal is above
VCC3,nominal + 0.3V within a single clock period.
The overshoot threshold duration must not exceed
20 percent of the period.
Tektronics
6245)
is
recommended.
The
measurement should be taken at the CLK (AK18)
pin and its nearest VSS pin (AM18).
UNDERSHOOT THRESHOLD DURATION
SPECIFICATION: A snapshot of the clock signal
should be taken at 500 mV/div and 500 pS/div.
Adjust the vertical position and horizontal offset
MAXIMUM OVERSHOOT, MAXIMUM
UNDERSHOOT AND MAXIMUM RINGBACK
SPECIFICATIONS: The display should show
continuous sampling (e.g., infinite persistence) of
the waveform at 500 mV/div and 5 nS/div for a
recommended duration of approximately five
seconds. Adjust the vertical position to measure
the maximum overshoot and associated ringback
with the largest possible granularity. Similarly,
readjust the vertical position to measure the
maximum undershoot and associated ringback.
position to view the threshold duration.
The
undershoot threshold duration is defined as the sum
of all time during which the clock signal is below -
0.3V within a single clock period. The undershoot
threshold duration must not exceed 20 percent of
the period.
These overshoot and undershoot specifications are
illustrated graphically in Figures 14 through 17.
There is no allowance for crossing the maximum
overshoot, maximum undershoot or maximum
ringback specifications.
Maximum Overshoot Level
Overshoot Threshold Level
VCC3, nominal
Overshoot
Threshold
Duration
Figure 14. Maximum Overshoot Level, Overshoot Threshold Level, and Overshoot Threshold
Duration
55
INTEL [ INTEL ]
