Intel 810A3, Design Manual

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Intel
®
810A3 Chipset Design Guide 3-1
SC242 Processor Design Guidelines
SC242 Processor Design Guidelines
3
This chapter provides SC242 processor design guidelines including Layout Guidelines, general
topology, minimizing crosstalk, motherboard layout rules for non-AGTL+ signals, THRMDP and
THRMDN, and motherboard frequency select for SC242 designs. The layout guidelines are
processor-specific and should be used in conjunction with the
Chapter 4, “Layout and Routing
Guidelines” . See Chapter 5, “Advanced System Bus Design” for more details on AGTL+ layout
guidelines.
3.1 Intel
®
Pentium
®
III Processors Layout Guidelines
The following layout guide supports designs using Intel

Pentium
®
III processors utilizing the
SC242 connector and Intel

810A3 chipset at system bus speeds of 100 MHz.
Initial Timing Analysis
Table 3-1 lists the AGTL+ component timings of the processors and GMCH defined at the pins.
These timings are for reference only; obtain each processor’s specifications from its
respective Electrical, Mechanical, and Thermal Specification and appropriate Intel

810A3
chipset component specification.
NOTES:
1. All times in nanoseconds.
2. Numbers in table are for reference only. These timing parameters are subject to change. Please check the
appropriate component documentation for valid timing parameter values.
3. T
SU_MIN
= 2.72 ns assumes the GMCH sees a minimum edge rate equal to 0.3 V/ns.
Table 3-2 gives an example AGTL+ initial maximum flight time and Table 3-3 is an example
minimum flight time calculation for a 100 MHz, uni-processor system using Intel

Pentium

III
processor/Intel
®
810A3 Chipset system bus. Note that assumed values for clock skew and clock
jitter were used. Clock skew and clock jitter values are dependent on the clock components
and distribution method chosen for a particular design and must be budgeted into the initial
timing equations as appropriate for each design.
Table 3-1. Intel
®
Pentium
®
III Processor and GMCH AGTL+ Parameters for Example
Calculations
1
IC Parameters
Intel
®
Pentium III processor
core at 100 MHz System Bus
GMCH Notes
Clock to Output maximum (T
CO_MAX
) 2.70 3.63 2
Clock to Output minimum (T
CO_MIN
) -0.10 0.50 2
Setup time (T
SU_MIN
) 1.20 2.27 2,3
Hold time (T
HOLD
) 0.80 0.28