Intel 200 MHz FV8050366200 User Manual

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5/23/97 10:47 AM    24318502.DOC

This section describes the electrical differences
between the Pentium processor with MMX
technology and the Pentium processor
133/150/166/200, as well as the AC and DC
specifications of the Pentium processor with MMX
technology.

When designing a Pentium processor with MMX
technology  system from a Pentium processor
133/150/166/200 system, there are a number of
electrical differences that require attention. Designing
a single motherboard that supports various members
of the Pentium processor family including the
Pentium processor with MMX technology, Pentium
processor 133/150/166/200, Pentium OverDrive

®

processor, or future Pentium OverDrive processor
can be easily accomplished. Refer to the 

Pentium

®

Processor Flexible Motherboard Design Guidelines

application note (Order Number 243187) for more
information and specific implementation examples.

The following sections highlight key electrical issues
pertaining to the Pentium processor with MMX
technology power supplies, connection specifications
and buffer models.

The main electrical difference between the Pentium
processor with MMX technology and the Pentium
processor 133/150/166/200 is the operating voltage.
The Pentium processor with MMX technology
requires two separate voltage inputs, V

CC2

 and V

CC3

.

The V

CC2

 pins supply power to the Pentium

processor with MMX technology core, while the V

CC3

pins supply power to the processor I/O pins.

The Pentium processor 133/150/166/200, on the
other hand, requires a single voltage supply for all
V

CC

 pins. This single supply powers both the core

and I/O pins of the Pentium processor
133/150/166/200.

By connecting all of the V

CC2

 pins together and all

the V

CC3

 pins together on separate power islands,

Pentium processor 133/150/166/200 designs can
easily be converted to support the Pentium
processor with MMX technology. In order to maintain
compatibility with Pentium processor
133/150/166/200-based platforms, the Pentium
processor with MMX technology supports the
standard 3.3V specification on its V

CC3

 pins.

There is no specific power sequence required for
powering up or powering down the separate V

CC2

and V

CC3

 supplies of the Pentium processor with

MMX technology. It is recommended that the V

CC2

and V

CC3

 supplies be either both ON or both OFF

within one second of each other.

Connection specifications for the power and ground
inputs, 3.3V inputs and outputs, and the NC/INC and
unused inputs are discussed in the following
sections.

For clean on-chip power distribution, the Pentium
processor with MMX technology in PPGA and SPGA
packages has 28 V

CC3

 (I/O power), 25 V

CC2

 (core

power) and 53 V

SS

 (ground) inputs. Power and

ground connections must be made to all external V

CC

and V

SS

 pins of the Pentium processor with MMX

technology. On the circuit board all V

CC3

 pins must

be connected to a 3.3V V

CC

 plane. All V

CC2

 pins

must be connected to a 2.8V V

CC

 plane. All V

SS

 pins

must be connected to a V

SS

 plane.

The values of V

CC2

 and V

CC3

 should be measured at

the bottom side of the processor pins using an
oscilloscope with a 3 dB bandwidth of at least
20 

MHz (100 MS/s digital sampling rate). There

should be a short isolation ground lead attached to a
processor pin on the bottom side of the board.

The measurement should be taken at the following
V

CC

/V

SS

 pairs: AN13/AM10, AN21/AM18, AN29/

AM26, AC37/Z36, U37/R36, L37/H36, A25/B28,
A17/B20, A7/B10, G1/K2, S1/V2, AC1/Z2. One-half
of these pins are V

CC2

 while the others are V

CC3

; the

operating ranges for the V

CC2

 and V

CC3

 pins are