Intel 810A3, Design Manual

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PGA370 Processor Design Guidelines
2-4 Intel
®
810A3 Chipset Design Guide
2.2.2 Layout Guidelines for Intel
®
Pentium
®
III Processors
The following layout guide supports designs using Intel

Celeron

processors and Intel
®
Pentium
®
III
processor with the Intel

810A3 chipset. The solution covers system bus speeds of
66 MHz for the Intel

Celeron

processor and 100 MHz for the Intel
®
Pentium
®
III processors.
The solution proposed in this segment requires the motherboard design to terminate the system bus
AGTL+ signals with a 56
Ω
±5% Rtt. The Intel
®
Pentium
®
III processor must also be configured
to 110
Ω
internal Rtt.
Note: 133 MHz system bus frequency is not supported on the Intel

810A3 chipset.
Initial Timing Analysis
Table 2-3 lists the AGTL+ component timings of the processors and 82810A3 GMCH defined at
the pins. These timings are for reference only; obtain each processor’s specifications from its
respective processor 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. 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.
G35 Reserved Reserved VTT AGTL+ termination voltage
S33 Reserved Reserved VTT AGTL+ termination voltage
S37 Reserved Reserved VTT AGTL+ termination voltage
U35 Reserved Reserved VTT AGTL+ termination voltage
U37 Reserved Reserved VTT AGTL+ termination voltage
V4 Reserved Reserved BERR# Bus error
W3 Reserved Reserved A34# Additional AGTL+ address
X4 RESET# RESET# RESET2#
Processor reset (Celeron PPGA,
Intel Pentium III 128K)
X6 Reserved Reserved A32# Additional AGTL+ address
Y33 GND Reserved CLKREF 1.25V PLL reference
Table 2-2. Processor Pin Definition Comparison (Continued)
Pin #
Intel
®
Celeron
TM
(PPGA)
pin name
Intel
®
Pentium
®
III
128K
pin name
Intel
®
Pentium
®
III
256K
pin name
Function
Table 2-3. Intel
®
Pentium
®
III Processor and GMCH AGTL+ Parameters for Example
Calculations
IC Parameters
Intel
®
Pentium
®
III
Processor Core at
100 MHz System Bus
GMCH at
100 MHz
System Bus
Notes
Clock to Output maximum (T
CO_MAX
) 3.25 5.35 2
Clock to Output minimum (T
CO_MIN
) 0.40 1.27 2
Setup time (T
SU_MIN
) 1.20 2.72 2,3
Hold time (T
HOLD
) 1.0 0.10