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Power source switchover method for high voltage battery

IP.com Disclosure Number: IPCOM000012591D
Original Publication Date: 2003-May-19
Included in the Prior Art Database: 2003-May-19

Publishing Venue

IBM

Abstract

A battery for Notebook PC is classified by the number of internal battery cells which are connected in series. And battery output voltage is set by it. As for Li+ battery, maximum output voltage of 3S battery (three cells) is 12.6V, and in case of 4S (four cells) battery, it is 16.8V. Power for the system is supplied from AC adapter when AC adapter is attached to the system, and when AC adapter is removed, it is supplied from battery. The control method of switchover of power supply is different between the case of "maximum battery output voltage is lower than AC adapter voltage" and "maximum battery output voltage is higher than AC adapter voltage". The former control method can be designed simply, that is to prepare a detection circuit for AC adapter and two FETs and a FET controller. The latter control method need consider how control the switchover of power supply without any trouble.