Patent ID: 7439708

Claim:
A battery charger comprising: a pair of connection terminals across which a secondary battery is connected; a first power supply circuit that is connected to the pair of connection terminals and supplies power to the secondary battery; a second power supply circuit that produces a first voltage and a second voltage, the second voltage having a value greater than a value of the first voltage; a first component operable when applied with the first voltage; a second component operable when applied with the second voltage; and a control section that controls both the first power supply circuit and the second power supply circuit so that the first power supply circuit is disabled but the second power supply circuit is enabled when the secondary battery is not connected across the pair of connection terminals, and that both the first power supply circuit and the second power supply circuit are enabled when the secondary battery is connected across the pair of connection terminals, wherein the second power supply circuit produces the first voltage when the secondary battery is not connected across the pair of connection terminals, and produces the second voltage when the secondary battery is connected across the pair of connection terminals; wherein the second power supply circuit generates the first voltage in response to a first instruction from the control section, and generates the second voltage in response to a second instruction from the control section; and wherein the second power supply circuit comprises: a switching power source controlled to selectively provide a first output and a second output in response to the first instruction and the second instruction from the control section, respectively; a first voltage generating circuit that generates the first voltage in response to the first and second outputs; and a second voltage generating circuit that generates the second voltage in response to the second output.