Power Management: Dell� Latitude� LM
Power Management: Latitude LM
How Power Management
Works | Closing the Display
| Power Management Features
| Conserving Battery Power
| Power Conservation
Guidelines | Standby Mode | Suspend Mode | Suspend-to-Disk Mode | Dimming the Display | Turning Off the Hard-Disk
Drive
Battery power is automatically conserved each time an AC power
source is used to run the computer. The battery's life expectancy
is largely determined by the number of charges it receives, so
always use an AC power source to run the computer if one is
available.
When power conservation features are used, some of the
performance of the computer is traded off for increased battery
operating time. For example, if the hard-disk drive is turned
off, a delay may occur the next time the computer tries to access
the hard-disk drive.
Other power conservation features, such as standby mode and
suspend mode, stop almost all system activity and suspend-to-disk
mode turns off all power to the computer. They allow the user to
maximize power conservation when work is interrupted.
To conserve power, close the display when the computer is not
in use. When the display is closed and an external monitor is not
connected, the computer beeps 1 time and goes into Suspend mode.
If the computer receives a modem call from an external modem
while the display is closed, the call is answered if the computer
has not entered suspend-to-disk mode.
To resume work, open the display.
 |
NOTE: If an external monitor is connected when
the display is closed, the computer does not activate
suspend mode. |
| Feature |
Activate/Deactivate |
| Standby mode |
To activate this feature, select the
Standby Time-Out option in the Power Menu of the Setup
program. To deactivate the feature, move the cursor or
press any key on the built-in or external keyboard. |
| Suspend mode |
To activate this feature, press
<Fn><Esc> or set the Suspend Time-Out option
in the Power Menu of the Setup program. When suspend mode
is activated, the computer beeps once and the suspend
mode indicator of the status display panel blinks every 4
seconds. To deactivate this feature, press a key on the
built-in keyboard. |
| Suspend-to-disk mode |
To activate this feature, press
<Fn><a> or set the Suspend To Disk Time-Out
option in the Power Menu of the Setup program. To resume
using the computer, press the power button on the
built-in keyboard. |
| Dimming the display |
To activate this feature, set the Dim
Mode Time-Out option in the Power Menu of the Setup
program. To increase the brightness of the display, press
any key on the built-in keyboard. |
| Turning off the hard-disk drive |
To activate this feature, set the
Hard-Disk Time-Out option in the Power Menu of the Setup
program. The computer automatically turns the hard-disk
drive back on the next time the microprocessor accesses
the drive. |
Power Menu
Use the PowerPanel to adjust the way the computer uses battery
power. PowerPanel settings override corresponding settings in the
Setup program.
Use the Power menu of the Setup program. Options in the Power
menu slow down or stop some internal devices when the computer is
idle.
Take advantage of the computer’s power management modes
when you leave the computer unattended for long periods of time.
Standby mode, suspend mode, and suspend-to-disk mode allow you to
maximize power conservation when your work is interrupted.
When the computer is using battery power, remove PC Cards that
you are not using.
Experiment with power conservation features to achieve the
optimum power conservation for your work environment.
| |
NOTE: You might have to trade some of the
computer’s performance for increased battery
operating time. For example, if you turn off the
hard-disk drive, you may experience a delay the next time
the computer tries to access the drive. |
The PowerPanel lets you adjust the computer’s power
management options without rebooting the computer to enter the
Setup program. The PowerPanel and the Power menu in the Setup
program share many power management options, but PowerPanel
settings override those for corresponding options in the Setup
program.
When you start the computer, the minimized PowerPanel toolbar
appears.
 To access PowerPanel’s extensive Help files,
click PowerPanel on the toolbar, and then select
Help. . . from the menu options.
Use the PowerPanel to:
- Assign power profiles for maximum battery life or maximum
performance
- Turn off hardware components when they are not being used
- Customize the computer’s power conservation modes
In general, the lower the value you set for each time-out, the
longer your battery's charge lasts. On the other hand, setting
high time-out values tends to optimize the computer's
performance. For best results, experiment as follows:
- Use the computer with all the options set at their
default values.
- Use the computer with all the time-out options disabled
or set to Off.
- Use the computer with all the time-out options set to
their minimum values. Evaluate the way that the different
time-out settings affect how long you can operate the
computer on battery power versus the relative efficiency
of how your software performs.
Standby mode conserves battery power by stopping some computer
activity, but leaves the computer ready to resume operations
immediately. Use standby mode when you leave the computer
unattended for less than a few minutes. Resume normal computer
activity by moving the cursor or pressing any key on the built-in
keyboard (the computer takes less than a second to return to
normal operation).
You can tell the computer to enter standby mode automatically
after no I/O activity occurs for a specified length of time. To
program this feature, use the Standby Time-Out option in the
Power menu of the Setup program. The computer automatically
answers modem calls while it is in standby mode.
Standby mode conserves battery power by turning off the
display and reducing power to the microprocessor, VGA PCI bus,
diskette drive or CD-ROM drive (if installed), serial and
parallel ports, hard-disk drive, PC Card controller, internal
speakers and microphone, and external speakers and microphone (if
attached).
Suspend mode conserves battery power by stopping almost all
computer activity, but leaves the computer ready to resume
operations in seconds. Use suspend mode whenever you leave the
computer unattended for more than a few minutes. Resume normal
computer activity by pressing any key on the built-in keyboard
(the computer may take several seconds to return to normal
operation).
You can activate suspend mode by pressing
<Fn><Esc>. You can also tell the computer to enter
suspend mode automatically after no I/O activity occurs for a
specified length of time. To program this feature, use the
Suspend Time-Out option in the Power menu of the Setup program.
When the computer is in suspend mode, icons cycle through the
keyboard indicators area of the status display panel.
While in suspend mode, the computer automatically answers
calls to external modems attached to the computer’s serial
port. You can also use the Alarm Resume option in the Power menu
of the Setup program to determine how long the computer remains
in suspend mode before resuming normal operation.
Suspend mode conserves battery power by turning off the
microprocessor, external cache, hard-disk drive, serial and
parallel ports, PS/2 ports, diskette drive or CD-ROM drive (if
installed), external keyboard or mouse (if attached), display, PC
Card controller, internal speakers and microphone, and external
speakers and microphone (if attached). In suspend mode, the
computer reduces power to the PC Card controller.
Suspend-to-disk mode copies all system data to a reserved area
on the hard-disk drive and then turns off all power to the
computer. When you resume normal operation, the same programs
will be running and the same files will be open that were loaded
before you activated this mode.
| |
NOTES: Suspend-to-disk mode helps preserve system
data by quickly saving it to the hard-disk drive if you
are about to run out of battery power. Place
the computer in suspend-to-disk mode if you intend to
store the computer for longer than 40 days.
Suspend-to-disk mode preserves the configuration
information stored in NVRAM. The reserve battery
maintains this information, but may run out of energy
after 40 days.
|
To activate suspend-to-disk mode immediately, press
<Fn><a>. You can also tell the computer to enter
suspend-to-disk mode automatically after no I/O activity occurs
for a specified length of time. To program this feature, use the
Suspend-to-Disk Time-Out option in the Power Menu of the Setup
program.
To resume using the computer after activating suspend-to-disk
mode, press the power button. It takes a few seconds for the
computer to return to its previous state.
If you connect or remove devices while the computer is in
suspend-to-disk mode, the computer automatically recognizes the
new devices connected when it resumes normal operation.
Some PC Cards may not operate correctly after resuming from
suspend-to-disk mode. If you encounter problems with a card,
remove and reinsert it.
| |
NOTE: Suspend-to-disk mode requires a special
file on your hard-disk drive that sets aside enough disk
space to store the contents of the computer's memory.
Dell creates an appropriately sized suspend-to-disk file
before shipping the computer to you. If you remove the
file or add memory to the computer, or if your hard-disk
drive becomes corrupted, you must recreate the file
before you can again use suspend-to-disk mode. |
The suspend-to-disk file on your hard-disk drive can be
accessed by the operating system or application programs. When
suspend-to-disk mode is activated, all system data is stored in
this file.
Use the following instructions to create a suspend-to-disk
file if you are about to install a new hard-disk drive, if you
removed the file, or if you are rebuilding a corrupted hard-disk
drive. You might want to print these instructions before you
begin this procedure.
| |
NOTE: If you installed memory modules to increase
system memory, delete the suspend-to-disk file, and then
begin this procedure at step 3. To delete the
suspend-to-disk file, type: PHDISK /DELETE /FILE
at the MS-DOS� prompt and press <Enter>.
|
- Use the FDISK utility to partition the hard-disk drive.
See your MS-DOS documentation for instructions on using
the FDISK utility.
- Format the hard-disk drive. See your MS-DOS documentation
for instructions on formatting the hard-disk drive.
- At the MS-DOS prompt, type:
c:
and press <Enter>.
- If you are installing a new hard-disk drive or rebuilding
a corrupted drive, create a subdirectory named \dell\util.
- Copy the PHDISK utility from the software support
diskette (program diskette); type:
cd \dell\utiland
press <Enter>.
- Type:
PHDISK /CREATE /FILE
and press <Enter>. The utility calculates the size
of the file based on current system requirements. The size of
the file is calculated in kilobytes. The file should be equal
to the amount of system memory in the computer, plus 2 MB to
handle video memory and additional system requirements.
- Follow the instructions on the display to create the
suspend-to-disk file.
To check the size of the suspend-to-disk file, type:
PHDISK/INFO
at the MS-DOS prompt and press <Enter>.
You can slowly dim the display to conserve battery power when
you are working with the computer intermittently or when the
computer is performing a task that does not require your input.
To enable and disable this feature, use the Dim Mode Time-Out
option in the Power menu of the Setup program. When you want to
use the display again, press any key on the keyboard. The display
takes a few seconds to return to its original brightness.
| |
NOTE: To save battery power, Dell recommends that
you always set this option to the lowest setting that
affords comfortable viewing. You can conserve up to 5% of
battery power by using the minimum brightness. |
The computer can conserve power by turning off the hard-disk
drive. Use this feature when the computer is engaged in activity
that rarely accesses the hard-disk drive, such as calculations.
To enable and disable this feature, use the Hard-Disk Drive
Time-Out option in the Power menu of the Setup program. The
computer automatically turns the hard-disk drive back on the next
time the microprocessor accesses the drive.
Dell discourages the use of screen savers while using the
battery or batteries as the only source of power.
The setting of the automatic save-to-disk sequence should be
increased to more than 30 minutes (for auto-backup functions) to
decrease the use of the hard-disk drive.
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