1 Hardware Overview

1.5 Power Supply

1.5Power Supply

The power supply supplies seven different voltages to the system board and performs the following functions:

1.A/D conversion

The EC uses 10-bit sampling for A/D conversion to determine the following values:

AC adaptor current

Battery and temperature

2.AC adaptor and battery check

The EC checks the following by A/D converted values:

Battery installed

The EC checks the following by GPIO values:

AC adaptor connected

3.Abnormal check

The EC determines whether the condition is abnormal, and if so, stores an error code into the error register.

4.Input port management

The EC monitors the following input signal status:

System power ON/OFF status

Direct CD power ON/OFF status

5.Beep and LED control

Beep is caused by the low battery status.

The EC controls the following two kinds of LED DC IN LED (one color: green)

Green = indicates AC adaptor is connected

Battery LED (two colors: orange and green)

Green solid = The battery is fully charged.

1-14

Satellite P20-25 Series Maintenance Manual

Page 28
Image 28
Toshiba P25 manual Hardware Overview Power Supply