User's Manual

4.2.9.4 DC-DC Converter/Battery Charger Circuit
The power supply board includes two DC-DC Converter circuits and a
battery charging circuit that operate the notebook and charge the internal
batteries when the AC Adapter is attached to the notebook. The converters
operate from an input voltage between 7 VDC and 20 VDC (from the AC
adapter) and generate the regulated voltages required to power all internal
logic circuits and charge the internal batteries. When the AC adapter is not
used, the DC-DC converters are powered by the output of the internal
battery pack (s) (nominal 8.4V).
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Theory of Operation