Patent ID: 9077198
Filing Date: 2015-07-07
Classification: H02J

Abstract:
1. A method to control a composite battery charger charging a battery having a battery voltage, comprised of a combination of a switching regulator and a linear battery charger, the switching regulator including a power switch which is turned on and off with a duty cycle by a pulse width modulator (PWM) and the switching regulator having an output voltage providing supply voltage for the linear battery charger and for one or more device circuits consuming a device current, the method comprising: turning a pass transistor of the linear charger substantially fully on in a constant current (CC) operating mode; generating a control signal based on a difference of a signal representative of a sensed battery charge current provided through the pass transistor and a first reference value based on a target battery charge current; and the pulse width modulator controlling the duty cycle of the power switch of the switching regulator based on the control signal to maintain a battery charge current substantially constant approximately corresponding to the first reference value, substantially independently of the device current and the battery voltage until the battery voltage approaches a maximum fully charged battery voltage level.