BATTERY CHARGER APPARATUS WITH A DIGITAL CHARGE REDUCTION LOOP

摘要

A battery charger apparatus for charging a battery, comprises a charge-current control circuit for receiving a charge-current control signal to control an amount of charge current being drawn from an input source, e.g., a USB port or a line adapter; an analog control circuit for generating an analog control signal representative of a maximum amount of charge current to be used to charge a battery; a digital charge reduction loop including a circuit for determining a charge-current adjustment signal based on a source voltage of the input source; a counter for generating a digital count value based on the charge-current adjustment signal; and a digital-to-analog converter (DAC) for generating a DAC control signal based on the digital count value of the counter, the DAC control signal being representative of a reduced amount of charge current to be used to charge the battery; and a switching mechanism for selecting one of the analog control signal or the DAC control signal based on the source voltage, the selected control signal being used as the charge-current control signal to the charge-current control circuit.