Building the Power-Efficient PC: A Developer's Guide to ACPI Power Management
This book provides developers and integrators with practical knowledge and design techniques for building PCs that address the increasing demand for energy conservation.
TABLE OF CONTENTS Building the Power-Efficient PC: A Developer's Guide to ACPI Power Management
Chapter 6: Dual Mode Desktop Power Delivery
The dual mode power subsystem, capable of meeting power requirements for both full power and standby operation, is the key concept in the new generation of power-managed PCs. Dual mode power allows computers to take all the needed power when the computer is fully operational and switch to a very low power state when the computer is idle.
Several examples of power delivery using a standard ATX power supply and switching transistors on the motherboard are described in this chapter. In addition, an example of a fully integrated power supply is also described.
Dual Power Supply Outputs for Power Management
Dual mode power can be implemented either with standard power supply and switching circuits on the motherboard, or with the integrated dual mode power supply.
A typical ATX power supply includes both a main converter capable of delivering high power to the system during normal operation, and a standby converter to supply power to the system in the soft off state. (For example, standby current is required for the power switch, which is an electronic push on button signaling to the controller that the main power needs to be turned on.) Dual power circuits on the motherboard to derive dual outputs from the main and standby converters in the standby power supply are implemented using field effect transistors (FET), voltage regulators and control logic to combine 5V standby voltage and 5V/3.3V main voltages.
Integrated dual mode power supplies implement the switching circuits in the power supply, delivering the dual...
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