Digital controlled battery charging system

A battery charging system having an input terminal and an output terminal coupled to a battery, comprising:

• a first switch, coupled between the input terminal of the battery charging system and the output terminal of the battery charging system;
• a plurality of analog control loops, configured to receive a plurality of reference signals, a plurality of feedback signals and a slope compensation signal, and configured to provide a plurality of loop control signals based on the plurality of reference signals, the plurality of feedback signals and the slope compensation signal;
• wherein the plurality of analog control loops comprises an input voltage control loop, configured to receive an input voltage feedback signal representative of an input voltage, the slope compensation signal and an input voltage reference signal, and configured to provide a first loop control signal via comparing the input voltage reference signal with a first compounded signal obtained by a subtraction between the input voltage feedback signal and the slope compensation signal;
• a digital control unit, configured to receive the plurality of loop control signals, and configured to provide a switching control signal to control the first switch automatically in response to one of the plurality of analog control loops, wherein when one of the plurality of loop control signals transits to a first state, the switching control signal is configured to turn OFF the first switch, and to turn ON the first switch again until a predetermined OFF time period expires.

A control circuit for a battery charging system, the battery charging system having a switching circuit, and the control circuit comprising:

• a plurality of analog control loops, configured to receive a plurality of reference signals, a plurality of feedback signals and a slope compensation signal, and configured to provide a plurality of loop control signals based on the plurality of reference signals, the plurality of feedback signals and the slope compensation signal;
• a digital control unit, configured to receive the plurality of loop control signals and provide a switching control signal to control the switching circuit based on the plurality of loop control signals, the digital control unit is further configured to provide a digital slope control signal to adjust an amplitude of the slope compensation signal, wherein the digital control unit automatically chooses one of the plurality of analog control loops to control the switching circuit;
• and
• a slope generating unit, configured to provide the slope compensation signal based on the digital slope control signal and the switching control signal
• wherein the digital control unit is further configured to provide a plurality of digital reference signals, and the control circuit is configured to provide the plurality of reference signals based on the plurality of digital reference signals;
• wherein the digital control unit further comprises:
• an analog-to-digital conversion unit, configured to provide a digital signal based on analog-to-digital converting of one of the plurality of feedback signals;
• a digital compensation loop, configured to provide a plurality of error compensation signals, wherein each of the plurality of error compensation signal is generated based on a difference between the digital signal and one of the plurality of digital reference signals;
• a plurality of operation modules, each of the plurality of operation modules is configured to provide a summation of one of the plurality of error compensation signals and one of the plurality of digital reference signals;
• and
• a plurality of digital-to-analog conversion units, each of the plurality of digital-to-analog conversion units having an input terminal coupled to one of the plurality of operation modules to receive the summation of one of the plurality of error compensation signals and one of the plurality of digital reference signals, and an output terminal configured to provide one of the plurality of reference signals via digital-to-analog converting.