Patent attributes
A method and apparatus for controlling a composite battery charger including a switching regulator and a linear charger charging a battery connected to it, whereby the switching regulator provides the supply voltage for the linear charger and Device Circuits. The control method and circuit fully turns on the pass device of the linear charger in a constant current operating mode and the switching regulator is controlled to maintain a constant charge current through the pass device while also supplying device current to the Device Circuits. The device current may vary. The method and circuit limits the dissipation of the pass device of the linear charger by reducing the supply voltage as a function of the charge current in the CC/CV transition region of the battery charger and by reducing the charge current as a function of the battery voltage if the battery voltage is below a predetermined value related to a predetermined minimum supply voltage value.
