Abstract: System and method for discharging a capacitor. An example system includes a signal detector and a discharge control component. The signal detector is configured to receive an input signal and generate a detection signal based on at least information associated with the input signal, the input signal being associated with an alternate current signal received by a capacitor including a first capacitor terminal and a second capacitor terminal. The discharge control component configured to receive at least the detection signal and generate an output signal to discharge the capacitor if the detection signal satisfies one or more conditions.

Abstract: System and method are provided for regulating a power converter. The system includes a signal processing component configured to receive a first input signal and a second input signal, process information associated with the first input signal and the second input signal, and output a drive signal to a switch based on at least information associated with the first input signal and the second input signal. The first input signal is associated with at least a feedback signal related to an output voltage of the power converter. The second input signal is associated with at least a primary current flowing through a primary winding of the power converter. The signal processing component is further configured to change a peak value of the primary current within a first predetermined range, and change the switching frequency of the power converter within a second predetermined range.

Abstract: System and method for providing at least an output current to one or more light emitting diodes. The system includes a control component configured to receive at least a demagnetization signal, a sensed signal and a reference signal and to generate a control signal based on at least information associated with the demagnetization signal, the sensed signal and the reference signal, and a logic and driving component configured to receive at least the control signal and output a drive signal to a switch based on at least information associated with the control signal. The switch is connected to a first diode terminal of a diode and a first inductor terminal of an inductor. The diode further includes a second diode terminal, and the inductor further includes a second inductor terminal.

Abstract: System and method for driving a bipolar junction transistor for a power converter. The system includes a current generator configured to output a drive current signal to a bipolar junction transistor to adjust a primary current flowing through a primary winding of a power converter. The current generator is further configured to output the drive current signal to turn on the bipolar junction transistor during a first time period, a second time period, and a third time period, the second time period separating the first time period from the third time period, drive the bipolar junction transistor to operate in a hard-saturation region during the first time period and the second time period, and drive the bipolar junction transistor to operate in a quasi-saturation region during the third time period.

Abstract: System and method for regulating a power conversion system. An example system controller includes a signal processing component and a driving component. The signal processing component is configured to receive a feedback signal associated with an output signal of a power conversion system and generate a processed signal based on at least information associated with the feedback signal. The driving component is configured to generate a drive signal based on at least information associated with the processed signal and output the drive signal to a switch in order to affect a primary current flowing through a primary winding, the drive signal being associated with a demagnetization period corresponding to a demagnetization process of the power conversion system. The signal processing component is further configured to, sample and hold the feedback signal a plurality of times during the demagnetization period to generate a plurality of sampled and held signals.

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 a power conversion system. A system controller for regulating a power conversion system includes a first controller terminal and a second controller terminal. Additionally, the system controller is configured to receive an input signal at the first controller terminal, and generate a drive signal at the second controller terminal based at least in part on the input signal to turn on or off a transistor in order to affect a current associated with a secondary winding of the power conversion system. Moreover, the system controller is further configured to determine whether the input signal is larger than a first threshold at a first time, in response to the input signal being determined to be larger than the first threshold at the first time, determine whether the input signal is smaller than a second threshold at a second time.

Abstract: System controller and method for a power converter. For example, the system controller includes a first current controller configured to receive a first input signal and generate a first output signal based at least in part on the first input signal, a second current controller configured to receive a compensation signal and a second input signal and generate a second output signal based at least in part on the second input signal, and a drive signal generator configured to receive the first output signal and the second output signal, generate a first drive signal based at least in part on the first output signal and the second output signal, and generate a second drive signal based at least in part on the first output signal and the second output signal.

Abstract: System controller and method for a power converter. For example, the system controller includes a first current controller configured to receive a first input signal and generate a first output signal based at least in part on the first input signal, a second current controller configured to receive a compensation signal and a second input signal and generate a second output signal based at least in part on the second input signal, and a drive signal generator configured to receive the first output signal and the second output signal, generate a first drive signal based at least in part on the first output signal and the second output signal, and generate a second drive signal based at least in part on the first output signal and the second output signal.

Abstract: System and method for controlling one or more light emitting diodes. For example, the system includes a bleeder configured to receive a rectified voltage generated by a rectifying bridge, and a dimmer detector configured to receive an input voltage generated by a voltage divider, determine whether or not the rectified voltage is associated with a TRIAC dimmer, and output a control signal to the bleeder. The voltage divider is configured to receive the rectified voltage, and the input voltage indicates a magnitude of the rectified voltage.

Abstract: System controller and method for a lighting system according to certain embodiments. For example, the system controller includes a first controller terminal configured to receive a first signal, and a second controller terminal coupled to a first transistor terminal of a transistor. The transistor further includes a second transistor terminal and a third transistor terminal. The second transistor terminal is coupled to a first winding terminal of a winding, and the winding further includes a second winding terminal coupled to a capacitor. Additionally, the system controller includes a third controller terminal coupled to the third transistor terminal of the transistor, and a fourth controller terminal coupled to a resistor and configured to receive a second signal. The second signal represents a magnitude of a current flowing through at least the winding, the third controller terminal, the fourth controller terminal, and the resistor.

Abstract: Controller and method for a power converter. For example, the controller includes a first controller terminal coupled to a gate terminal of a transistor. The transistor further includes a drain terminal and a source terminal, and the first controller terminal is at a first voltage as a first function of time. Additionally, the controller includes a second controller terminal coupled to the source terminal. The second controller terminal is at a second voltage as a second function of time. Moreover, the controller includes a third controller terminal coupled to a first resistor terminal of a resistor. The resistor further includes a second resistor terminal, and the third controller terminal is at a third voltage as a third function of time. Also, the controller includes a fourth controller terminal coupled to a first capacitor terminal of a capacitor.

Abstract: Systems and methods are provided for amplifying multiple input signals to generate multiple output signals. An example system includes: a first channel configured to receive a first input signal and a second input signal and generate a first output signal and a second output signal based at least in part on the first input signal and the second input signal; and a second channel configured to receive a third input signal and a fourth input signal and generate a third output signal and a fourth output signal based at least in part on the third input signal and the fourth input signal. A first differential signal is equal to the first input signal minus the second input signal. A second differential signal is equal to the third input signal minus the fourth input signal. The first output signal corresponds to a first phase.

Abstract: Systems and methods are provided for protecting a power conversion system. A system controller includes a two-level protection component and a driving component. The two-level protection component is configured to detect an output power of a power conversion system and generate a protection signal based on at least information associated with the output power. The driving component is configured to generate a drive signal based on at least information associated with the protection signal and output the drive signal to a switch associated with a primary current flowing through a primary winding of the power conversion system. The driving component is further configured to generate the drive signal corresponding to a first switching frequency to generate the output power equal to a first power threshold and generate the drive signal corresponding to a second switching frequency to generate the output power equal to a second power threshold.

Abstract: Systems and methods are provided for protecting a power conversion system. A system controller includes a first controller terminal and a second controller terminal. The first controller terminal is configured to provide a drive signal to close and open a switch to affect a first current flowing through a primary winding of a power conversion system. The second controller terminal is configured to receive first input signals during one or more first switching periods and receive second input signals during one or more second switching periods. The system controller is configured to determine whether a temperature associated with the power conversion system is larger than a predetermined temperature threshold, and in response to the temperature associated with the power conversion system being larger than the predetermined temperature threshold, generate the drive signal to cause the switch open and remain open to protect the power conversion system.

Abstract: Systems and methods are provided herein for current regulation. An example system controller includes: a first controller terminal configured to receive an input voltage, the first controller terminal being further configured to allow a first current flowing into the system controller based at least in part on the input voltage in response to one or more switches being closed; a second controller terminal configured to allow the first current to flow out of the system controller through the second controller terminal in response to the one or more switches being closed; a fourth controller terminal coupled to the third controller terminal through a first capacitor, the first capacitor not being any part of the system controller; and an error amplifier configured to generate a compensation signal based at least in part on the current sensing signal, the error amplifier including a second capacitor.

Abstract: System controller and method for regulating a power converter. For example, the system controller includes a first controller terminal and a second controller terminal. The system controller is configured to receive, at the first controller terminal, an input signal, generate a drive signal based at least in part on the input signal, and output, at the second controller terminal, the drive signal to a switch to affect a current associated with a secondary winding of the power converter. The system controller is further configured to detect a first duration of a demagnetization period associated with the secondary winding based at least in part on the input signal, determine a second duration of a time period for the drive signal based at least in part on the first duration, and keep the drive signal at a first logic level during the entire time period.

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: Systems and methods are provided for regulating a power converter. An example system controller includes: a driver configured to output a drive signal to a switch to affect a current flowing through an inductive winding of a power converter, the drive signal being associated with a switching period including an on-time period and an off-time period. The switch is closed in response to the drive signal during the on-time period. The switch is opened in response to the drive signal during the off-time period. A duty cycle is equal to a duration of the on-time period divided by a duration of the switching period. One minus the duty cycle is equal to a parameter. The system controller is configured to keep a multiplication product of the duty cycle, the parameter and the duration of the on-time period approximately constant.

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.