Lenovo 59P5107 Datenblatt PDF herunterladen (Seite 45)

Low Voltage Intel

Xeon

™

Processor at 1.60 GHz, 2.0 GHz and 2.4 GHz

Datasheet 45

Note: The following three notes apply to the activity factor.

1. Activity factor for common clock AGTL+ signals is referenced to BCLK[1:0] frequency.

2. Activity factor for source synchronous (2x) signals is referenced to ADSTB[1:0]#.

3. Activity factor for source synchronous (4x) signals is referenced to DSTBP[3:0]#and

DSTBN[3:0]#.

3.3.5 Reading Overshoot/Undershoot Specification Tables

The processor overshoot/undershoot specification is not a simple single value. Instead, many

factors are needed to determine what the overshoot/undershoot specification is. In addition to the

magnitude of the overshoot, the following parameters must also be known: the width of the

overshoot 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. For AGTL+ signals operating in

the 4X source synchronous domain, Table 22 should be used. For AGTL+ signals operating in

the 2X source synchronous domain, Table 23 should be used. When the signal is an AGTL+

signal operating in the common clock domain, Table 24 should be used. Finally, for all other

signals residing in the 33

MHz domain (asynchronous GTL+, TAP, etc.), Table 25 should be

used.

2. Determine the

magnitude of the overshoot or the undershoot (relative to V

3. Determine the

activity factor (how often does this overshoot occurs).

4. Next, from the appropriate specification table, determine the

maximum pulse duration (in

nanoseconds) allowed.

5. Compare the specified maximum pulse duration to the signal being measured. When the pulse

duration measured is less than the pulse duration shown in the table, the signal meets the

specifications.

Undershoot events must be analyzed separately from overshoot events as they are mutually

exclusive.

3.3.6 Determining When a System Meets the Overshoot/Undershoot

Specifications

The overshoot/undershoot specifications listed in the following tables specify the allowable

overshoot/undershoot for a single overshoot/undershoot event. However most systems may have

multiple overshoot and/or undershoot events that each have their own set of parameters (duration,

AF and magnitude). While each overshoot on its own may meet the overshoot specification, when

the total impact of all overshoot events are considered, the system may fail. A guideline to ensure a

system passes the overshoot and undershoot specifications is presented as follows:

• Ensure that no signal ever exceeds V

or -0.25 V OR

• When only one overshoot/undershoot event magnitude occurs, ensure it meets the overshoot/

undershoot specifications in the following tables

• When multiple overshoots and/or multiple undershoots occur, measure the worst case pulse

duration for each magnitude and compare the results against the AF = 1 specifications. When

all of these worst case overshoot or undershoot events meet the specifications (measured time

< specifications) in the table (where AF=1), the system passes.

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