Abstract: System and method for regulating a power converter. A system for regulating a power converter includes a controller, a first switch, and a second switch. The controller is configured to generate a first switching signal and a second switching signal. The first switch is configured to receive the first switching signal, the first switch being coupled to an auxiliary winding of the power converter further including a primary winding and a secondary winding. The second switch is configured to receive the second switching signal and coupled to the primary winding of the power converter. The controller is further configured to, change, at a first time, the second switching signal to open the second switch, maintain, from the first time to a second time, the first switching signal to keep the first switch open, and change, at the second time, the first switching signal to close the first switch.

Abstract: System and method for regulating an output of a power conversion system. An example system controller includes a signal generator and a modulation and drive component. The signal generator is configured to receive at least a first signal indicating a magnitude of an input voltage received by a primary winding of a power conversion system and receive a second signal indicating a magnitude of a primary current flowing through the primary winding, and generate a third signal. The modulation and drive component is configured to receive at least the third signal, generate a drive signal based on at least information associated with the third signal, and output the drive signal to a switch to affect the primary current.

Abstract: System and method for dimming control of one or more light emitting diodes. An example system includes one or more signal processing components configured to receive a first signal associated with a TRIAC dimmer, process information associated with the first signal, determine whether the TRIAC dimmer is in a first condition or a second condition, generate a second signal based on at least information associated with the first signal, and send the second signal to a switch. The one or more signal processing components are further configured to, if the TRIAC dimmer is determined to be in the first condition, generate the second signal to cause the switch to be opened and closed corresponding to a modulation frequency.

Abstract: System and method for regulating a power conversion system. A system controller for regulating a power conversion system includes an operation-mode-selection component and a driving component. The operation-mode-selection component is configured to receive a first signal related to an output load of the power conversion system and a second signal related to an input signal received by the power conversion system and output a mode-selection signal based on at least information associated with the first signal and the second signal. The driving component is configured to receive the mode-selection signal and generate a drive signal based on at least information associated with the mode-selection signal, the driving signal corresponding to a switching frequency.

Abstract: System and method for protecting a power conversion system. An example system controller includes a protection component and a driving component. The protection component is configured to receive a demagnetization signal generated based on at least information associated with a feedback signal of the power conversion system, process information associated with the demagnetization signal and a detected voltage generated based on at least information associated with the feedback signal, and generate a protection signal based on at least information associated with the detected voltage and the demagnetization signal. The driving component is configured to receive the protection signal and output a driving signal to a switch configured to affect a primary current flowing through a primary winding of the power conversion system. The detected voltage is related to an output voltage of the power conversion system. The demagnetization signal is related to a demagnetization period of the power conversion system.

Abstract: System and method for generating one or more ramp signals. The method includes an oscillator configured to generate at least a clock signal, and a ramp signal generator configured to receive at least the clock signal and generate a first ramp signal. Additionally, the ramp signal generator is coupled to a first resistor including a first terminal and a second terminal. The first resistor is configured to receive an input voltage at the first terminal and is coupled to the ramp signal generator at the second terminal. Moreover, the first resistor is associated with a first resistance value. Also, the clock signal is associated with at least a predetermined frequency. The predetermined frequency does not change if the input voltage changes from a first magnitude to a second magnitude. The first magnitude is different from the second magnitude.

Abstract: System and method for adjusting brightness of one or more cold-cathode fluorescent lamps. The system includes a voltage selector configured to receive a dimming voltage and a first threshold voltage and generate an output voltage. The output voltage is selected from a group consisting of the dimming voltage and the first threshold voltage. Additionally, the system includes an oscillator coupled to a first capacitor and configured to generate a ramp signal with the first capacitor, and a signal generator configured to receive the ramp signal and the output voltage and generate a first signal. The first signal corresponds to a lamp brightness level. Moreover, the system includes a brightness detector configured to receive the first signal and output a second signal. The second signal indicates whether the lamp brightness level is higher than a threshold brightness level.

Abstract: System and method for protecting a power converter. An example system controller for protecting a power converter includes a signal generator, a comparator, and a modulation and drive component. The signal generator is configured to generate a threshold signal. The comparator is configured to receive the threshold signal and a current sensing signal and generate a comparison signal based on at least information associated with the threshold signal and the current sensing signal, the current sensing signal indicating a magnitude of a primary current flowing through a primary winding of a power converter. The modulation and drive component is coupled to the signal generator.

Abstract: System and method for regulating an output voltage of a power conversion system. The system includes an error amplifier coupled to a capacitor. The error amplifier is configured to receive a reference voltage, a first voltage, and an adjustment current and to generate a compensation voltage with the capacitor. The first voltage is associated with a feedback voltage. Additionally, the system includes a current generator configured to receive the compensation voltage and generate the adjustment current and a first current, and a signal generator configured to receive the first current and a second current. The signal generator is further configured to receive a sensing voltage and to generate a modulation signal. Moreover, the system includes the gate driver directly or indirectly coupled to the signal generator and configured to generate a drive signal based on at least information associated with the modulation signal.