Four_cell_NiCad_power_management

Published:2009/7/24 22:47:00 Author:Jessie | From:SeekIC

Figure 8-56 shows one channel of an LTC1156 used to regulate the output of a four-cell NiCad battery pack to power a notebook or palmtop computer. Figure 8-57 shows typical four-cell NiCad discharge charaqteristics. As long as the input voltage to the regulator is sufficient to produce 5 V at the output, the regulator limits at 5 V. When the battery-pack voltage drops below 5 V, the MOSFET is fully enhanced, and acts as a direct connection between the battery and the computer circuits. A battery-voltage monitor in the microprocessor decides when the battery voltage drops below 4.6 V, and housekeeping is performed (data storage, etc.) before the batteries are completely discharged. The other three channels of the LTC 1156 act as switches (under microprocessor control) to power the remaining sections of the computer. The number of switches can be increased by adding more LTC1155 or LTC1156 circuits as needed. LINEAR TECHNOLOGY, APPLICATION NOTE 53, P. 11.



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