Power Plane Partitions; Power Plane Partitions For Slot-1 Motherboard; Figure 2-14. Atx Power Plane Partitions For Slot-1 System - VIA Technologies Apollo Pro133A Design Manual

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2.2.6 Power Plane Partitions

The required voltage sources in an Apollo Pro133A system design are: +/-12V, +/-5V, CPU core voltage (1.3V~3.3V defined by
the five voltage identification pins of the Slot-1 or Socket-370 CPU), 3.3V, 2.5V and 1.5V. The power layer is partitioned into
several power islands with five major power sources: VCC_CORE (CPU core voltage), VCC3 (3.3V), VTT (1.5V GTL+
termination voltage), VDDQ (3.3V for AGP 2X mode or 1.5V for AGP 4X mode) and VCC5 (+5V). The remaining power
sources will have their own small power islands or be routed as power traces 20-50 mils wide.

2.2.6.1 Power Plane Partitions for Slot-1 Motherboard

Figure 2-14 shows the power plane partitions on a typical ATX form factor. The island associated with VCC_CORE covers
almost half the area of the Pentium-II socket for the Slot-1 CPU. The VCC3 island covers an area, which contains the North
Bridge chip, the South Bridge chip, all DIMM slots and a half of the AGP slot. The VDDQ island occupies most AGP signal
routing area. The rest of the power layer belongs to VCC5. Different power plane partitions for Micro-ATX form factor are
shown in Figure 2-15. The distribution of power islands is almost the same between ATX and Micro-ATX, except the smaller
VCC5 island on the power layer of the Micro-ATX.
Preliminary Revision 0.5, November 19, 1999
VCC5 Island
VCC3 Island
VT82C
686A
VCC5 Island

Figure 2-14. ATX Power Plane Partitions for Slot-1 System

Design Guide - VT82C694X Apollo Pro133 with VT82C686A
VCC_CORE Island
VTT Island
VDDQ Island
IDE1
IDE2
21
Back Panel Area
VCC5 Island
VCC3 Island
694X
510-PIN
FDC
VCC5 Island
Motherboard Design Guidelines
CLK
GEN.