Intel Itanium 2 Processor manual Overshoot/Undershoot Pulse Duration, Activity Factor

Electrical Specifications

Figure 2-3. System Bus Signal Waveform Exhibiting Overshoot/Undershoot

Maximum	Time-dependent
Absolute
	Overshoot
Overshoot

VMAX

VCTERM

VREF

VOL

GND

VMIN

Time-dependent

Maximum Undershoot

Absolute

Undershoot

000588

2.5.2Overshoot/Undershoot Pulse Duration

Pulse duration describes the total time an overshoot/undershoot event exceeds the overshoot/undershoot reference voltage (VCTERM/GND). The total time could encompass several oscillations above the reference voltage. Multiple overshoot/undershoot pulses within a single overshoot/undershoot event may need to be measured to determine the total pulse duration.

Note: Oscillations below the reference voltage cannot be subtracted from the total overshoot/undershoot pulse duration.

2.5.3Activity Factor

Activity factor (AF) describes the frequency of overshoot (or undershoot) occurrence relative to a clock. Since the highest frequency of assertion of any common clock 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. For source synchronous signals (data, and associated strobes), the activity factor is in reference to the strobe edge. The highest frequency of assertion of any source synchronous signal is every active edge of its associated strobe. So, an AF = 1 indicates that the specific overshoot (or undershoot) waveform occurs every other strobe cycle. The specifications provided in Table 2-14through Table 2-21show the maximum pulse duration allowed for a given overshoot/undershoot magnitude at a specific activity factor. Each table entry is independent of all others, meaning that the pulse duration reflects the existence of overshoot/undershoot events of that magnitude ONLY. A platform with an overshoot/undershoot that just meets the pulse duration for a specific magnitude where the AF <1, means that there can be no other overshoot/undershoot events, even of lesser magnitude (if AF = 1, then the event occurs at all times and no other events can occur).

24 Datasheet