Intel 820E manual Power Delivery, Terminology and Definitions, Term Definition

Intel® 820E Chipset

R

6.System Design Considerations

6.1.Power Delivery

6.1.1.Terminology and Definitions

Term	Definition
Suspend to	In the STR state, the system state is stored in main memory and all unnecessary
RAM (STR)	system logic is turned off. Only main memory and logic required to wake the
	system remain powered. This state is used in the Customer Reference Board to
	satisfy the S3 ACPI power management state.
Full-power	During full-power operation, all components on the motherboard remain powered.
operation	Note that full-power operation includes both the full-on operating state and the S1
	(processor Stop Grant state) state.
Suspend	During suspend operation, power is removed from some components on the
operation	motherboard. The customer reference board supports two suspend states: Suspend
	to RAM (S3) and Soft-Off (S5).
Power rails	An ATX power supply has 6 power rails: +5 V, -5 V, +12 V, -12 V, +3.3 V, and
	5 VSB. In addition to these power rails, several other power rails are created with
	voltage regulators on the Intel 820E chipset reference board.
Core power rail	These power rails are on only during full-power operation. These power rails are on
	when the PSON signal is asserted to the ATX power supply. The following core
	power rails are distributed directly from the ATX power supply: ±5 V, ±12 V, and
	+3.3 V.
Standby power	These power rails are on during the suspend operation. (These rails also are on
rail	during full-power operation.) These rails are on at all times (when the power supply
	is plugged into AC power). The only standby power rail that is distributed directly
	from the ATX power supply is 5 VSB (5 V standby). Other standby rails are created
	with voltage regulators on the motherboard.
Derived power	A derived power rail is any power rail generated from another power rail using an
rail	on-board voltage regulator. For example, 3.3 VSB usually is derived (on the
	motherboard) from 5 VSB using a voltage regulator. (On the Intel 820E chipset
	reference board, 3.3 VSB is derived from 5V_DUAL.)
Dual power rail	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 a standby
	supply during the suspend operation and is derived from a core supply during full-
	power operation. Note that the voltage on a dual power rail may be misleading.

Design Guide 183