VS440FX Motherboard Technical Product Specification
26
Front Panel I/O Connectors (continued)
Pin Signal Name Connector
13 HD_PWR +5 V HD LED
14 Key
15 HD Active#
16 HD_PWR
17 No connect/Key none
18 Ground Sleep/Power LED
19 Key
20 PWR_LED
21 No connect/Key none
22 Ground Reset
23 SW_RST
24 Ground Speaker
25 Key
26 PIEZO_IN
27 SPKR_HDR
1.11.9.2 Power On Connector
You must connect this header to a power switch that could be placed on the front panel. A
momentary ground must be applied to the SW_ON pin to signal the supply to turn on or off. This
requirement is usually satisfied by using a SPST normally open momentary contact switch.
Because of the motherboard’s internal debounce circuitry, the ground must be applied for at least
50 ms. To prevent double-clicking, at least 2 seconds must pass before the power supply will
recognize another on/off signal.
1.11.9.3 Sleep/Resume
When APM is enabled in the system BIOS and the operating system’s APM driver is loaded, the
system can enter Sleep (Standby) mode in one of three ways:
• Optional front panel Sleep/Resume button
• Hot key defined in the BIOS Setup program
• Prolonged system inactivity; the default timeout is 10 minutes and can be changed in Setup
A Sleep/Resume button is supported by the 2-pin header located on the front panel I/O connector.
The front panel Sleep/Resume switch must be a momentary SPST type that is normally open.
Closing the Sleep/Resume switch generates a System Management Interrupt (SMI) to the
processor, which immediately goes into System Management Mode (SMM). While the system is
in Sleep mode it is fully capable of responding to and servicing external interrupts (such as an
incoming fax) even though the monitor turns on only if a keyboard or mouse interrupt occurs. To
reactivate the system you must press the Sleep/Resume button again, or use the keyboard or
mouse.
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