Systems and methods of energy saving in a battery charging system

A battery charging system for delivering battery power to a battery-operable device, comprising:

• a battery charging controller including a digital core circuit, a charger mode control circuit component, and an energy saving circuit component;
• an alternating current (AC) adapter input port;
• a battery pack;
• and
• a pulse width modulation (PWM) power stage including a plurality of active switch elements for implementing, at a PWM switching frequency, a PWM switching scheme to provide a battery charging output to the battery pack,
• wherein the digital core circuit is operative:
• to regulate the battery charging output during at least a pre-charging period, a current-controlled charging period, and a voltage-controlled charging period of the battery pack;
• during one or both of the current-controlled charging period and the voltage-controlled charging period of the battery pack, to control the charger mode control circuit component to operate the energy saving circuit component in a zeroth energy saving mode of the battery charging system;
• to monitor an AC adapter current from the AC adapter input port to detect a reduction in the AC adapter current to a predetermined current level;
• having detected the reduction in the AC adapter current to the predetermined current level, to control the charger mode control circuit component to transition the energy saving circuit component from operating in the zeroth energy saving mode to a first energy saving mode of the battery charging system;
• to monitor the PWM switching frequency of the PWM power stage to detect a reduction in the PWM switching frequency to a predetermined frequency threshold, the reduction in the PWM switching frequency being in response to the reduction in the AC adapter current;
• having detected the reduction in the PWM switching frequency to the predetermined frequency threshold, to control the charger mode control circuit component to transition the energy saving circuit component from operating in the first energy saving mode to a second energy saving mode of the battery charging system,
• wherein the PWM power stage includes a first high-side switch element and a second high-side switch element connected in parallel on a high side of a buck converter switch, and a first low-side switch element and a second low-side switch element connected in parallel on a low side of the buck converter switch, the first high-side switch element being connected in series with the first low-side switch element, and the second high-side switch element being connected in series with the second low-side switch element;
• and
• while operating the energy saving circuit component in the zeroth energy saving mode, to actuate the first and second high-side switch elements of the buck converter switch substantially simultaneously.

A method of a battery charging system for delivering battery power to a battery-operable device, comprising:

• regulating, by a digital core circuit within a battery charging controller, a battery charging output of a pulse width modulation (PWM) power stage during at least a current-controlled charging period and a voltage-controlled charging period of a battery pack, the battery charging controller including a charger mode control circuit component and an energy saving circuit component;
• during one or both of the current-controlled charging period and the voltage-controlled charging period of the battery pack, controlling the charger mode control circuit component to operate the energy saving circuit component in a zeroth energy saving mode of the battery charging system;
• monitoring, by the digital core circuit, an AC adapter current from an AC adapter input port of the battery charging system to detect a reduction in the AC adapter current to a predetermined current level;
• having detected the reduction in the AC adapter current to the predetermined current level, controlling the charger mode control circuit component to transition the energy saving circuit component from operating in the zeroth energy saving mode to a first energy saving mode of the battery charging system;
• monitoring, by the digital core circuit, a PWM switching frequency of the PWM power stage to detect a reduction in the PWM switching frequency to a predetermined frequency threshold, the reduction in the PWM switching frequency being in response to the reduction in the AC adapter current;
• having detected the reduction in the PWM switching frequency to the predetermined frequency threshold, controlling the charger mode control circuit component to transition the energy saving circuit component from operating in the first energy saving mode to a second energy saving mode of the battery charging system, the PWM power stage including a first high-side switch element and a second high-side switch element connected in parallel on a high side of a buck converter switch, and a first low-side switch element and a second low-side switch element connected in parallel on a low side of the buck converter switch, the first high-side switch element being connected in series with the first low-side switch element, and the second high-side switch element being connected in series with the second low-side switch element;
• and
• while operating the energy saving circuit component in the zeroth energy saving mode, actuating the first and second high-side switch elements of the buck converter switch substantially simultaneously.