Patent ID: 9130468
Filing Date: 2015-09-08
Classification: H02M

Abstract:
1. A constant voltage constant current (CVCC) controller configured for a flyback converter, said CVCC controller comprising: a) a current controller configured to generate an error signal by calculating a difference between an output current feedback signal from a current feedback circuit and a reference current; b) a voltage controller configured to receive an output voltage feedback signal from a voltage feedback circuit and a reference voltage, and to generate a control signal; c) a selector comprising a first switch configured to receive said error signal and being controllable by said control signal, said selector being configured to control said flyback converter to operate in a first operation mode or a second operation mode based on said control signal, wherein said selector comprises a second switch coupled to said first switch and being controllable by an inverted version of said control signal, wherein said selector is configured to generate a constant voltage control signal based on said error signal when said flyback converter is operating in said first operation mode, and to generate a constant current control signal based on said error signal when said flyback converter is operating in said second operation mode, wherein said selector comprises a discharging circuit coupled between said second switch and ground, and a first capacitor coupled to said first and second switches and ground, wherein a cross voltage on said first capacitor is configured as said constant voltage control signal or said constant current control signal; d) a pulse-width modulation (PWM) controller configured to generate a PWM control signal to control a main switch of said flyback converter, wherein said PWM controller is configured to generate a constant voltage signal based on said constant voltage control signal to maintain an output voltage of said flyback converter as substantially constant when said flyback converter operates in said first operation mode, and wherein said PWM controller is configured to generate a constant current signal based on said constant current control signal to maintain an output current of said flyback converter as substantially constant when said flyback converter operates in said second operation mode; and e) a timer configured to measure a discharging time of a secondary winding of said flyback converter, and to generate a timing signal therefrom.