Patent ID: 7999516

Claim:
A battery charging circuit comprising: a power converter operable for providing a charging power to a battery pack; a charging control switch coupled to said battery pack and operable for transferring said charging power to said battery pack; and a charger controller coupled to said charging control switch and said power converter, wherein said charger controller comprises: a comparator operable for comparing a battery voltage of said battery pack with a first predetermined battery voltage; a selector coupled to said comparator and operable for selecting a signal from a first signal and a second signal to control said charging control switch according to an output of said comparator; and a multiplier operable for multiplying a third signal representative of a cell number of said battery pack by a fourth signal representative of a predetermined maximum cell voltage of said battery pack, wherein said first predetermined battery voltage is a portion of a product of said third signal and said fourth signal, wherein said first signal is operable for controlling an output of said power converter.