BDM-610000084 Rev B
Chapter 4: Using the cpuModule 65
Power Management
The CML24BT cpuModule supports various powering mechanisms which allow the cpuModule to monitor
power consumption and temperature, and achieve minimal power consumption states. These unique features
include thermal monitoring and thermal throttling, as well as ACPI low power modes. Various wake options are
also available to resume normal system power.
Advanced Configuration and Power Interface (ACPI)
The cpuModule supports several different ACPI low power modes, including the S3, S4, and S5 sleeping states.
These suspend modes are described below:
•
S3 (Suspend to RAM):
When the system wakes from this mode, operating systems allow applications
to resume where they left off, as the state of the application is preserved in memory.
•
S4 (Hibernate):
When the system enters this state, the operating system will save the current state of
applications and relevant data to disk, thus allowing the system RAM to be powered down.
•
S5 (Soft-Off):
The system is in a soft off state, and must be rebooted when it wakes.
Power Button Modes
The soft power button input of the Utility Port 2.0 connector (
CN5
) can be configured by the operating system
as a suspend button (transition to S3) or as soft power button (transition to S5). Consult your operating system
documentation for information on how to configure it. The power button will always cause a transition to S5 if
pressed for 4 seconds or longer, without interaction from the operating system.
The soft power button of the Utility Port 2.0 connector (
CN5
) is the only mechanism to wake the system from
S4 and S5.
Low-Power Wake Options
The cpuModule supports several methods of waking from a low power state.
•
Resume from USB:
Operating systems that support S3 permit waking the system from the USB
interfaces. Common USB wake methods include insertion of a USB device, a USB keyboard stroke, or
movement from another USB device, such as mouse.
•
Resume on RTC Alarm / Timeout:
The RTC Alarm allows the system to turn on at a certain time every
day.
PME# or
the PME# signal on the PCI bus (
CN16
), or
Note
When the reset button of the Utility Port 2.0 connector is configured as a power button (via the
BIOS setup utility), it inherits the ACPI suspend and resume features of the power button.
Table 44 Supported ACPI Resume/Wake Mechanisms
Resume/Wake Mechanism
S3
S4
S5
Wake from USB
Y
—
—
Wake from RTC Alarm / Timeout
Y
—
—
Power Button Input (
CN5
)
Y
Y
Y
Summary of Contents for CML24BT cpuModules
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