Motherboard Design Guidelines; Ballout Assignment; Apollo Pro133A North Bridge Ballout Assignment; Figure 2-1. Major Signal Group Distributions Of The Apollo Pro133A Ballout (Top View) - VIA Technologies Apollo Pro133A Design Manual

Technologies, Inc.
Design Guide - VT82C694X Apollo Pro133 with VT82C686A
We Connect We Connect
M D G
OTHERBOARD ESIGN UIDELINES
This chapter describes general design schemes and recommended layout rules. It begins with the 510-pin BGA (Pro133A north
bridge) and 352-pin BGA (south bridge) ballout assignments. The following section contains the placement and routing of a
motherboard, PCB stack-up information and power requirements for a desktop system. Detailed placement, layout, and routing
guidelines for each bus or subsystem (Host bus, Memory subsystem, AGP bus and PCI bus) are described in section 2.4.

2.1 Ballout Assignment

Basically, the chipset ballout plays an important role in motherboard designs. It can determine the quality of the Printed Circuit
Board (PCB) layout. The reliability of a motherboard partially depends on the ballout of both the North Bridge and the South
Bridge. To achieve a cost effective and compact 4-layer motherboard, the ballouts should be well defined because they have an
inseparable relationship with component placement and PCB layout.

2.1.1 Apollo Pro133A North Bridge Ballout Assignment

Ballout of the Apollo Pro133A North Bridge is designed to minimize the number of crossover signals. Figure 2-1 shows the four
major signal group quadrants of the Apollo Pro133A Ballout. They are Host, Memory, AGP and PCI interfaces. Please refer to
the VT82C694X datasheet for more details on ball assignments.
1
A
PCI Host
Apollo Pro-133A
VT82C694X
AGP
510-PIN BGA
Memory
(Top View)

Figure 2-1. Major Signal Group Distributions of the Apollo Pro133A Ballout (Top View)

Preliminary Revision 0.5, November 19, 1999 7

Motherboard Design Guidelines