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: 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: 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 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: 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: System and method for regulating a power converter. The system includes a first signal generator configured to receive a first sensed signal and generate an output signal associated with demagnetization. The first sensed signal is related to a first winding coupled to a secondary winding for a power converter, and the secondary winding is associated with at least an output current for the power converter. Additionally, the system includes a ramping signal generator configured to receive the output signal and generate a ramping signal, and a first comparator configured to receive the ramping signal and a first threshold signal and generate a first comparison signal based on at least information associated with the ramping signal and the first threshold signal. Moreover, the system includes a second comparator configured to receive a second sensed signal and a second threshold signal and generate a second comparison signal.

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 controller and method for protecting a power converter. The system controller includes a first controller terminal configured to output a drive signal to a switch to affect a first current flowing through a primary winding of a power converter. The power converter further includes a secondary winding coupled to the primary winding, and the drive signal is associated with one or more switching periods. Additionally, the system controller includes a second controller terminal configured to receive a sensing voltage from a sensing resistor. The sensing voltage represents a magnitude of the first current flowing through the primary winding of the power converter. The system controller is configured to process information associated with the sensing voltage and a reference voltage, and determine whether an average output current of the power converter is larger than a current threshold.

Abstract: Systems and methods are provided for regulating a power converter. An example system controller includes: a first controller terminal configured to output a drive signal to a switch to affect a current flowing through a primary winding of a power converter, the drive signal being associated with a switching period corresponding to a switching frequency; and a second controller terminal configured to receive a feedback signal associated with an output voltage related to a secondary winding of the power converter. The first controller terminal is further configured to: output the drive signal to close the switch during the on-time period; and output the drive signal to open the switch during the off-time period. The system controller is configured to set the switching frequency to one or more frequency magnitudes, each of the one or more frequency magnitudes being smaller than or equal to an upper frequency limit.

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: 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: 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: 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: 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. 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 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: Systems and methods are provided for regulating a power converter. An example system controller includes: a first controller terminal configured to output a drive signal to a switch to affect a current flowing through a primary winding of a power converter, the drive signal being associated with a switching period corresponding to a switching frequency; and a second controller terminal configured to receive a feedback signal associated with an output voltage related to a secondary winding of the power converter. The first controller terminal is further configured to: output the drive signal to close the switch during the on-time period; and output the drive signal to open the switch during the off-time period. The system controller is configured to set the switching frequency to one or more frequency magnitudes, each of the one or more frequency magnitudes being smaller than or equal to an upper frequency limit.

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 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.