T4900CT
1.7 Power Supply
The power supply supplies five kinds of voltages to the T4900CT system board. The
T4900CT power supply has one microprocessor and it operates at 500 KHz (power off) or 20
MHz (power on). It contains the following functions:
1. Determines if the AC adapter or battery is connected to the computer.
2. Detects DC output and circuit malfunctions.
3. Controls the speaker and the brightness.
4. Controls the Battery capacity icon, Power on icon, and AC adapter icon on the
status indicator panel.
5. Turns the battery charging system on and off and detects a fully charged battery.
6. Determines if the power can be turned on and off.
7. Provides more accurate detection of a low battery.
8. Calculates the remaining battery capacity.
The power supply output rating is specified in table 1-5.
Table 1-5 Power supply board output rating
DC Regulation Maximum
Use for Name voltage tolerance current Ripple
(V) (%) (mA) (mV)
System logic, FDD, HDD VCC +5 ±5 2,200 100
RS-232C, Flash ROM 12V +12 ±5 120 240
Display DSPV +9.5 to +23 – 4.02 W –
RAM, CPU B3V +3.3 ±5 2,200 60
RS-232C M12V –7 to –12.6 – 10 –
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