Intel III Xeon 900 MHz 80526KY9002M Data Sheet
Product codes
80526KY9002M
PENTIUM® III XEON™ PROCESSOR AT 600 MHz to 1 GHz with 256KB L2 Cache
SIGNAL QUALITY
37
Intel recommends that platforms meet the Absolute Maximum Specifications for Overshoot and Undershoot on BCLK.
This ensures that the BCLK I/O Buffer will meet specifications regardless of Overshoot or Undershoot Pulse Duration
within a Clock cycle with 50% Duty Cycle. For all Pentium III Xeon processors at 600 MHz+ , the maximum Overshoot
level is 3.3V. The Absolute maximum Undershoot is –0.7V, where “maximum” is defined as the largest voltage potential
below ground.
This ensures that the BCLK I/O Buffer will meet specifications regardless of Overshoot or Undershoot Pulse Duration
within a Clock cycle with 50% Duty Cycle. For all Pentium III Xeon processors at 600 MHz+ , the maximum Overshoot
level is 3.3V. The Absolute maximum Undershoot is –0.7V, where “maximum” is defined as the largest voltage potential
below ground.
However, the Absolute Maximum Specifications can be relaxed for BCLK Undershoot if the Pulse Duration is accounted
for under worst-case conditions. Thus, a system with BCLK Undershoot below -0.7V must ensure that the worst case
Pulse Duration is less than or equal to the allowed Max Pulse Duration for the Worst Case Undershoot Magnitude. See
the Table 24.
for under worst-case conditions. Thus, a system with BCLK Undershoot below -0.7V must ensure that the worst case
Pulse Duration is less than or equal to the allowed Max Pulse Duration for the Worst Case Undershoot Magnitude. See
the Table 24.
Table 24. BCLK Overshoot/Undershoot Specifications
1,2,3,4,5,6,7
Undershoot
Magnitude
Max Pulse Duration (nS)
-0.85V
3.2
-0.8V
3.75
-0.75V
3.75
-0.7V
3.75
-0.65V
3.75
NOTES:
1.
Overshoot is measured relative to VSS.
2.
Undershoot is measured relative to VTT.
3.
Overshoot/Undershoot Pulse Duration is measured relative to 1.635V.
4.
Rinback below VTT cannot be subtracted from Overshoots/Undershoots.
5.
Lesser Undershoot does not allocate longer or larger Overshoot.
6.
OEM's are encouraged to follow Intel provided layout guidelines.
7.
All values specified by design characterization.
4.3.3 Measuring BCLK Overshoot/Undershoot
Overshoot on BCLK is measured relative to GND. By probing BCLK with an oscilloscope where the probe GND lead
makes good contact to a processor GND pin, BCLK Overshoot can be accurately measured to determine if the system
meets BCLK Overshoot Absolute Maximum Specifications.
makes good contact to a processor GND pin, BCLK Overshoot can be accurately measured to determine if the system
meets BCLK Overshoot Absolute Maximum Specifications.
Undershoot on BCLK is also measured relative to GND, again by probing BCLK with an oscilloscope where the probe
GND lead makes good contact to a processor GND pin. If the system does not meet the BCLK Undershoot Absolute
Maximum Specifications, then the Worst Case Undershoot Magnitude must be measured and the Pulse Duration of the
Undershoot must be accounted for. Pulse Duration measurements determine the total amount of time that the BCLK
signal spends below GND. Measuring from the earliest Falling Edge GND crossover to the latest Rising Edge GND
crossover provides the worst-case Undershoot Pulse Duration. When compared to the Specification Table, the Pulse
Duration and the Worst Case Undershoot Magnitude then determines if the system meets the BCLK
Overshoot/Undershoot Specifications. Note: the measured Pulse Duration must be less than or equal to the Specified
Max Pulse Duration for a given Worst Case Undershoot Magnitude.
GND lead makes good contact to a processor GND pin. If the system does not meet the BCLK Undershoot Absolute
Maximum Specifications, then the Worst Case Undershoot Magnitude must be measured and the Pulse Duration of the
Undershoot must be accounted for. Pulse Duration measurements determine the total amount of time that the BCLK
signal spends below GND. Measuring from the earliest Falling Edge GND crossover to the latest Rising Edge GND
crossover provides the worst-case Undershoot Pulse Duration. When compared to the Specification Table, the Pulse
Duration and the Worst Case Undershoot Magnitude then determines if the system meets the BCLK
Overshoot/Undershoot Specifications. Note: the measured Pulse Duration must be less than or equal to the Specified
Max Pulse Duration for a given Worst Case Undershoot Magnitude.
4.3.4 2.5V TOLERANT BUFFER RINGBACK SPECIFICATION
The ringback specification is the voltage at a receiving pin that a signal rings back to after achieving its maximum absolute
value. (See Figure 14 for an for an illustration of ringback.) Excessive ringback can cause false signal detection or extend
the propagation delay. Violations of the signal ringback specification are not allowed for 2.5V tolerant signals.
Table 25 shows signal ringback specifications for the 2.5V tolerant signals to be used for simulations at the processor
core.
value. (See Figure 14 for an for an illustration of ringback.) Excessive ringback can cause false signal detection or extend
the propagation delay. Violations of the signal ringback specification are not allowed for 2.5V tolerant signals.
Table 25 shows signal ringback specifications for the 2.5V tolerant signals to be used for simulations at the processor
core.
Table 25. Signal Ringback Specifications for 2.5V Tolerant Signal Simulation at the processor Core
Input Signal Group
Transition
Maximum Ringback
(with Input Diodes Present)
Unit
Figure
Non-AGTL+ Signals
0
→
1
1.7
V
14
Non-AGTL+ Signals
1
→
0
0.7
V
14