Power Supply - Toshiba Satellite U900 Maintenance Manual

1.3 Power Supply

1.3

Power Supply

The power supply unit provides constant voltage (19V) for the system board and performs the
following functions:
1. Power input monitor
 Checks whether the AC adapter (DC power supply) is connected to the computer.
 Checks whether the battery pack is connected to the computer.
 Monitors the DC power supply input voltage (AC Adapter output voltage).
2. Power supply's internal control
 Turns on and off the battery pack charging power supply.
 Issues a charging current instruction to the PWM control IC of the battery pack charging
power supply.
 Controls the supply of DC power supply input (AC Adapter output) to the power supply
unit.
 Controls the supply of power to the system block (load/logic circuit side).
 Controls forced shutdown if the power supply malfunctions.
3. Logic circuit control
 Instructs the gate array to enable/disable tuning the power on.
 Controls power-on/off operation.
4. Status display
 Turns on the Power LED (in White).
 Battery indicator (in Amber).
 DC-IN indicator (in White)
 Wireless indicator (in Amber)
5. External interface
 Performs communication through the I2C bus (via the internal EC/KBC).
 Transfers the power supply operation mode.
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