Compal NBLB2, Service Manual

Page: 17 / 152

NBLB2 Service Manual
11
S4 Sleeping State System Saves all system states and data onto disk prior to
power off the whole system.
5.4 Device Power Management
Under ACPI mode, the device specific power management supported by this
notebook includes the CPU throttling, monitor power management and the hard
disk.
5.4.1 CPU power management

ACPI mode
The operating system detects when the system is idle and places the CPU in one
of the 3 CPU low power states (C1, C2, C3 up to C6) depending on how much
latency it believes the system can afford.
The C1 state is simply the CPU halt instruction. The C2 state is the CPU stop
grant state. The C3 state is the CPU stops clock state. The CPU stays in this
state until an interrupt occurs.
5.4.2 Hard Disk
The operating system uses the spin down timer of the hard drive to set time-outs.
The BIOS time-out of the hard disk must be disabled in ACPI mode. The user can
sets the hard disk spin down time-out in the control panel power applet.
5.4.3 Display Device
The monitor can be turned off after a period of no activity based on the settings of
the OS.
5.4.4 System Wake Up Sources
The table below lists the wake up events for all low power states:
Events S3 S4 S5 Process required
Any key O X X X
Power button O O O X
LAN (On board) O O X O
RTC O O X O
Critical low battery O X X O
Field „Process required‟ identifies that further process for the occurred events must be
processed during wake up or resumes procedure.
5.4.4.1 LAN
LAN (On board)
The function of waking up the system from standby (DC/AC)/hibernation (AC mode) is
supported.
5.4.4.2 Real Time Clock Alarm
The Real Time Clock alarm interrupt will wake the system from Standby (DC/AC) /
Hibernation (AC mode)
5.4.4.3 Critical Low Battery
Critical low battery event can wake the system from Standby (DC mode) in ACPI mode.