Intel 810A3, Design Manual

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System Design Considerations
7-4 Intel
®
810A3 Chipset Design Guide
In addition to the power planes provided by the ATX power supply, an instantly available Intel

810A3 chipset system (using Suspend-to-RAM) requires additional power planes to be generated
on the board. The requirements for each power plane are documented in this section. In addition to
on-board voltage regulators, the Intel

810A3 chipset platform can have a 5V Dual Switch.
5V Dual Switch
This switch powers the 5V Dual plane from the 5V core ATX supply during full-power operation.
During Suspend-to-RAM, the 5V Dual plane will be powered from the 5V Standby power supply.
Note: The voltage on the 5V Dual plane is not 5.0V! There is a resistive drop through the 5V Dual Switch
that should be considered. Therefore, NO COMPONENTS should be connected directly to the 5V
Dual plane. On the Customer Reference Board, the only device connected directly to the 5V Dual
plane is the 3.3V voltage regulator (to regulate to lower voltages).
VCC
CORE
This power plane is used to power the processor. Refer to the latest revisions of the following doc-
uments:
•
VRM 8.4 Rev 1.6 DC-DC Converter Design Guidelines
•
PPGA 370 Power Delivery Guidelines
•
AP-907: Intel
®
Pentium

III
Power Distribution Guidelines
Note: This regulator is required in ALL designs.
V
TT
This power plane is used to power the AGTL+ termination resistors. Refer to the latest revisions of:
•
Intel
®
Pentium™
III
Processor Datasheet
Note: This regulator is required in ALL designs.
1.8V
The 1.8V plane powers the GMCH core, the ICH Hub interface I/O, and digital video out. This
voltage is obtained from using a 1.8V voltage regulator that regulates the voltage from the 3.3V
power supply voltage (or the 5V power supply voltage).
Note: This regulator is required in ALL designs.
Table 7-2. Intel

810A3 Chipset Voltage Regulator Specifications
Voltage Max Current
1.5 V 3.5 A
1.8 V 1.5 A
2.5 V 0.6 A
3.3 V 7.2 A
VCC
CORE
15.6 A