Abstract: A battery charging circuit includes a plurality of unit batteries that are connected in series; a current path forming unit that is connected between the unit batteries and forms a charging current path to one or more unit batteries selected by one or more selection signals; a control unit that senses the charging status of each of the plurality of the unit batteries, and generates the selection signals and controls the duty ratio according to the sensing results; and a charging electricity providing unit that controls the charging voltage provided to the charging current path forming unit according to the duty ratio of the charging control pulse.

Abstract: Provided is a battery charge circuit including a charging power supply unit configured to generate an internal voltage using an external power supply; a charging unit configured to measure voltages of first to fourth batteries, output measurement signals, and selectively charge at least one among the first to fourth batteries in response to charge control signals; and a control unit configured to select charging methods corresponding to the measurement signals among a plurality of charging methods stored therein, and generate the control signals corresponding to the charging methods.

Abstract: Provided is a battery charge circuit including a charging power supply unit configured to generate an internal voltage using an external power supply; a charging unit configured to measure voltages of a plurality of batteries, output measurement signals, and selectively charge at least one among the plurality of batteries in response to charge control signals; and a control unit configured to select charging methods corresponding to the measurement signals, and generate the control signals corresponding to the charging methods.

Abstract: Provided is an over-current protection apparatus including a current sensor configured to transform input current into a voltage signal, and output the voltage signal; an over-current sensing unit driven according to the voltage signal output from the current sensor; and an over-current determination unit configured to generate a switching unit driving signal, the logic level of which is determined according to a duration of an output signal of the over-current sensing unit.

Abstract: A phase synchronization circuit for AC voltage includes an optical phase detection unit that outputs a phase detection signal by detecting an externally provided first AC voltage; a power failure detection unit that outputs a power failure signal by detecting the power failure condition of the first AC voltage; a control unit that selectively activates a selection signal according to the control of the power failure detection signal and outputs a phase control signal according to the control of the phase detection signal; a second AC voltage generation unit that generates a second AC voltage to have the same phase of the first AC voltage when outputting a second AC voltage according to the control of the phase control signal; and a selection unit that outputs either the first AC voltage or the second AC voltage according to the control of the selection signal.