Intel 317443-001US - Manual (Page 31)

Intel ® Core TM 2 Duo processor with the Mobile Intel ® 945GME Express Chipset
May 2007 Manual
Order Number: 317443-001US 31
Theory of Operation—Intel ® 945GME Express Chipset
3.6.1 Transition to S3
If enabled, the transition to S3 from the full-on state can be accomplished in the
following ways:
• The OS performs the transition through software.
• Press the front panel power button for less than four seconds (assuming the OS
power management support has been enabled).
Note: The power button is accessed by adding a switch to the pins 5 and 6 on the front panel
header J8J1.
3.6.2 Transition to S4
“Wake on S4” (Suspend to disk) is controlled by the operating system.
3.6.3 Transition to S5
The transition to S5 is accomplished by the following means:
• Press the front panel power button for less than four seconds (if enabled through
the OS).
• Press the front panel power button for more than four seconds to activate power
button override.
3.6.4 Transition to Full-On
The transition to the Full-On state can be from S3 or S5. The transition from S3 is a low
latency transition that is triggered by one of the following wake events:
• Power management timer expiration
• Real Time Clock (RTC) triggered alarm
• Power button activation
• USB device interrupt
• ICH7M pin PME# assertion
• AC power loss
For AC power loss, the system operation is defined by register settings in the Intel
ICH7-M. Upon the return of power, a BIOS option, set prior to the power loss, allows
the system to either go immediately to the S5 state, or reboot to the Full-On state, no
matter what the state was before the power loss. External logic for this functionality is
not necessary. If the BIOS remains in the S5 state after AC power loss, only the power
button or the RTC alarm can bring the system out of the S5 state. The status of enabled
wake events will be lost.
3.7 Power Measurement Support
Power measurement resistors are provided on the platform to measure the power of
most subsystems. All power measurement resistors have a tolerance of 1%. The value
of these power measurement resistors are 2 mΩ by default. Power on a particular
subsystem is calculated using the following formula:
R
V
P
2
=