Display Inverter; External Ac Adapter - Compaq Armada e500 Series Reference Manual

MBAT (Master Battery)
MBAT is a common signal between all of the batteries. This signal is driven active by
the power source (either of the two batteries or the AC Adapter) that is powering the
system. If the device powering the system is removed MBAT will go inactive. When
this occurs any battery in the system will supply power to the system for 4 seconds
which will allow the 8051 microcontroller time to assign another battery as master.
MBAT will always be asserted in a system whenever there is a power source available
to power the system (i.e. either a battery or the AC Adapter).
Fuel Gauge
The system supports a fuel gauge for the battery pack. The fuel gauge is displayed on
the LCD or CRT by activating a hotkey Fn + F8 combination. It is removed by pressing
the hot key sequence again.
Each battery pack has a built-in fuel gauge on the pack to display the current status of
the battery's charge. The indicator provides fixed charge indicators of 0, 25, 50, 75, and
100 percent; the actual battery status is rounded off to one of these values. To save
power, the gauge is an on-demand type of indicator; that is, the indicators will only light
when the user presses a small membrane switch on the pack. The location of the gauge
permits the user to view it while the battery pack is in the battery charger.

Display Inverter

The display inverter is physically located in the LCD display assembly. The inverter
provides power for the LCD backlight, and decodes a low frequency input from the
system board that controls the brightness of the backlight.
The brightness PWM control is from the MSIO. The PWM signal can go from 0%
(minimum brightness setting however is 15%) to 100% (maximum brightness).
The on/off (BLON#) control for the inverter are from the ATI video controller. The
signal meets the timings and sequence required for LCD panels.

External AC Adapter

The external AC adapter supplies DC voltage to the DC/DC converter board for use by
the system to operate and/or charge the installed battery pack. The AC input
requirements are as follows:
Output capacity
Input voltage
Frequency
Input Power
The AC adapter also contains protection circuitry to ensure that the application of an
input voltage below the minimum specified above will not cause damage to the adapter
circuitry or cause failure of the input fuse.
9-4 Power Supply
50 watts continuous
90-264 VAC (auto-switching)
47-63 Hz
< 60 watts at 85 percent efficiency