HP Dc5850 Technical Reference Guide: HP Compaq dc5850 Series Business Desktop - Page 78

Power Control

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Power and Signal Distribution 7.2.3 Optional Energy Star Compliant PSUs Energy Star 4.0 (80-Plus, Bronze-compliant) active-PFC power supply units are available as an option for these systems. The specifications of the high-efficiency power supplies match those of the standard units except for the following aspects: ■ Efficiency: no less than 82 percent efficient at 20 or 100 percent of rated load and no less than 85 percent efficient at 50 percent of rated load (at 115 VAC/60 Hz and at 230 VAC/60 Hz input. ■ Power factor of greater than 0.9 measured at full rated load at 115 VAC/60 Hz and at 230 VAC/60 Hz input 7.3 Power Control The generation of +3, +5, and +12 VDC is controlled digitally with the PS On signal. When the PS On signal is asserted, all DC voltages are produced. When PS On is de-asserted, only auxiliary power (+5 AUX) is generated. The +5 AUX voltage is always produced as long as the system is connected to a live AC source. 7.3.1 Power Button The PS On signal is typically controlled through the Power Button which, when pressed and released, applies a negative (grounding) pulse to the power control logic on the system board. The resultant action of pressing the power button depends on the state and mode of the system at that time and is described as follows: System State Off On, ACPI Disabled On, ACPI Enabled Table 7-3. Power Button Actions Pressed Power Button Results In: Negative pulse, of which the falling edge results in power control logic asserting PS On signal to Power Supply Assembly, which then initializes. ACPI four-second counter is not active. Negative pulse, of which the falling edge causes power control logic to de-assert the PS On signal. ACPI four-second counter is not active. Pressed and Released Under Four Seconds: Negative pulse, of which the falling edge causes power control logic to generate SMI-, set a bit in the SMI source register, set a bit for button status, and start four-second counter. Software should clear the button status bit within four seconds and the Suspend state is entered. If the status bit is not cleared by software in four seconds PS On is de-asserted and the power supply assembly shuts down (this operation is meant as a guard if the OS is hung). Pressed and Held At least Four Seconds Before Release: If the button is held in for at least four seconds and then released, PS On is negated, de-activating the power supply. 7-4 www.hp.com Technical Reference Guide

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7-4
www.hp.com
Technical Reference Guide
Power and Signal Distribution
7.2.3 Optional Energy Star Compliant PSUs
Energy Star 4.0 (80-Plus, Bronze-compliant) active-PFC power supply units are available as an
option for these systems. The specifications of the high-efficiency power supplies match those of
the standard units except for the following aspects:
■
Efficiency: no less than 82 percent efficient at 20 or 100 percent of rated load and no less
than 85 percent efficient at 50 percent of rated load (at 115 VAC/60 Hz and at 230 VAC/60
Hz input.
■
Power factor of greater than 0.9 measured at full rated load at 115 VAC/60 Hz and at 230
VAC/60 Hz input
7.3 Power Control
The generation of +3, +5, and +
12 VDC is controlled digitally with the PS On signal. When the
PS On signal is asserted, all DC voltages are produced. When PS On is de-asserted, only
auxiliary power (+5 AUX) is generated. The +5 AUX voltage is always produced as long as the
system is connected to a live AC source.
7.3.1 Power Button
The PS On signal is typically controlled through the Power Button which, when pressed and
released, applies a negative (grounding) pulse to the power control logic on the system board.
The resultant action of pressing the power button depends on the state and mode of the system at
that time and is described as follows:
Table 7-3.
Power Button Actions
System State
Pressed Power Button Results In:
Off
Negative pulse, of which the falling edge results in power control logic
asserting PS On signal to Power Supply Assembly, which then initializes. ACPI
four-second counter is not active.
On, ACPI Disabled
Negative pulse, of which the falling edge causes power control logic to
de-assert the PS On signal. ACPI four-second counter is not active.
On, ACPI Enabled
Pressed and Released Under Four Seconds:
Negative pulse, of which the falling edge causes power control logic to
generate SMI-, set a bit in the SMI source register, set a bit for button status,
and start four-second counter. Software should clear the button status bit within
four seconds and the Suspend state is entered.
If the status bit is not cleared by
software in four seconds PS On is de-asserted and the power supply assembly
shuts down (this operation is meant as a guard if the OS is hung).
Pressed and Held At least Four Seconds Before Release:
If the button is held in for at least four seconds and then released,
PS On is
negated, de-activating the power supply.