Patent ID: 7012405
Filing Date: 2006-03-14
Classification: H02J

Abstract:
1. A charging circuit charging a secondary battery, comprising: a constant-current circuit part that is serially connected between an external direct-current power source and the secondary battery, and outputs, to the secondary battery, one of first and second constant currents in response to an input control signal; a constant-voltage circuit part that is connected in parallel with said constant-current circuit part, and charges the secondary battery by applying a predetermined constant voltage thereto; a battery voltage detection circuit part that detects and outputs a battery voltage of the secondary battery; a charge current detection circuit part that outputs a predetermined charge completion signal when said constant-voltage circuit part stops outputting a current; and a charge control circuit part that stops operations of said constant-current circuit part and said constant-voltage circuit part when the charge completion signal is input, wherein, when the battery voltage of the secondary battery is lower than a predetermined voltage, said charge control circuit part outputs, to said constant-current circuit part, the control signal to cause said constant-current circuit part to output the first constant current, and when the battery voltage of the secondary battery is equal to or greater than the predetermined voltage, said charge control circuit part outputs, to said constant-current circuit part, the control signal to cause the constant-current circuit part to output the second constant current that is greater than the first constant current.