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6.0
System Power Delivery Guide
This chapter provides an example for board power delivery of an EP80579-based
platform design. It provides the requirements and implemention of power sources for
system board designs.
Note:
There are many power delivery system implementations other than the example
described in this chapter.
6.1
Terminology and Definitions
Table 8.
Terminology
Term
Full Supply
Full Plane
Full Well
Power Rails
Suspend-To-RAM
(STR)
Full-power
Suspend Operation
Core Power
Standby Power Rail
Derived Power
Dual Power Rail
VRM and VRD
®
Intel
EP80579 Integrated Processor Product Line
Platform Design Guide
64
®
Intel
EP80579 Integrated Processor Product Line—System Power Delivery Guide
The external voltages and tolerances required to operate a component.
A group of like voltages connected to a particular power supply
Power planes which operate in normal and power management states
An ATX power supply has six power rails: +12V, –12V, +5V, –5V, +3.3V, and +5 VSBY.
In addition to these power rails coming off the power supply, several other power rails
are created by voltage regulators on the Development Board. The -12V and –5V power
rails are unused on the Development Board.
In the STR state, the system state is stored in main memory and all unnecessary
system logic is turned off. Only main memory and logic required to wake the system
remain powered. This state is used in the Development Board to satisfy the S3 ACPI
power management state.
S3 Cold - Classic S3 STR State
S3 Hot is not supported.
During full-power operation, all components on the motherboard remain powered. Note
that full-power operation includes both the full-on operating state (S0) and the S1 (CPU
stop-grant state) state.
During suspend operation, power is removed from some components on the
motherboard.
Core power refers to a power rail that is only on during full-power operation. These
power rails are on when the active-low PSON# signal is asserted to the ATX power
supply. The core power rails that are used directly from the power supply are: +12V,
+5V, and 3.3V.
A power rail that is on during suspend operation (these rails are also on during full
power operation) is a standby power rail. These rails may be on at all times as soon as
the power supply is plugged into AC power. The only standby power rail that is
distributed directly from the ATX power supply is +5 VSBY. The other standby rails on
the motherboard are created by voltage regulators.
A derived power rail is any power rail that is generated from another power rail using an
on-board voltage regulator.
A dual power rail is derived from different rails at different times (depending on the
power state of the system). Usually, a dual power rail is derived from standby supply
during suspend operation and derived from a core supply during full-power operation.
VRM stands for Voltage Regulator Module. VRD stands for Voltage Regulator Down.
Definition
Order Number: 320068-005US
May 2010
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