Abstract: A controller includes a primary controller and a secondary controller to control switching of a power switch and a secondary switch, respectively, coupled to an energy transfer element of a power converter. A first drive circuit is coupled to generate a first drive signal to enable a first ON section of the secondary drive signal after an ON section of the primary drive signal. A second drive circuit is coupled to generate a second drive signal to enable a second ON section of the secondary drive signal to store energy in the energy transfer element. The energy stored in the energy transfer element during the second ON section is coupled to reduce a switch voltage across the power switch prior to a next ON section of the primary drive signal. The secondary drive signal is generated in response to the first drive signal and the second drive signal.

Abstract: A power converter controller includes a switch driver circuit coupled to generate a drive signal to control switching of a power switch to control a transfer of energy from an input of the power converter to an output of the power converter. An input sense circuit is coupled to receive an input sense signal representative of the input of a power converter. A sense enable circuit is coupled to receive the drive signal to generate a sense enable signal to control the input sense circuit in response to the drive signal. The sense enable signal is coupled to control the input sense circuit to sense the input sense signal continuously in response to a first load condition, and sense the input sense signal only during a fraction of a switching period of the power switch in response to a second load condition.

Abstract: A controller for use in a power converter includes a switch controller coupled to a power switch coupled to an energy transfer element. The switch controller is coupled to receive a current sense signal representative of a drain current through the power switch. The switch controller is coupled to generate a drive signal to control switching of the power switch in response to the current sense signal and a modulated current limit signal to control a transfer of energy from an input to an output of the power converter. A current limit generator is coupled to generate a current limit signal. A jitter generator is coupled to generate a jitter signal. An arithmetic operator circuit is coupled to generate the modulated current limit signal in response to the current limit signal and the jitter signal.

Abstract: A switched mode power converter includes a switch, an energy transfer element coupled to the switch, and a controller that includes a delayed ramp generator coupled to generate a delayed ramp signal, an input charge control signal generator coupled to generate an input charge control signal representative of an integral of an input current sense signal and a ratio of an input voltage sense signal to an output voltage sense signal, and a drive signal generator coupled to receive the delayed ramp signal and the input charge control signal, to regulate an output of the switch mode power converter. The drive signal generator produces a drive signal responsive to the input charge control signal and the delayed ramp signal. The drive signal is coupled to control the switch of the switch mode power converter.

Abstract: A control circuit for use in an isolated power converter includes an output-side first controller having a switch control signal generator and an extremum locator. The switch control signal generator communicates a control signal to a second controller on the input side of the power converter via an isolated interface to initiate a transition of a switch from an OFF state to an ON state. The extremum locator enables the switch control signal generator to communicate the control signal in response to an oscillating voltage signal at an output terminal of the energy transfer element. The extremum locator enables the switch control signal generator such that the transition of the switch from the OFF state to the ON state occurs substantially at a time that the oscillating voltage signal reaches an extremum.

Abstract: A controller for use in a power converter includes a drive circuit coupled to generate a drive signal to control switching of a power switch to control a transfer of energy from a power converter input to a power converter output. An input for receiving an enable signal including enable events is responsive to the power converter output. The drive circuit is coupled to turn ON the power switch in response to the enable events and turn OFF the power switch in response to a power switch current reaching a current limit threshold. A current limit threshold generator is coupled to receive the enable events and vary the current limit threshold in response to the enable events of the enable signal.

Abstract: An example power supply includes an energy transfer element, a switch, and a controller. The switch is coupled to the energy transfer element to control a transfer of energy from an input to a galvanically isolated output of the power supply. The controller includes a delayed ramp generator, an integrator, an arithmetic operator, and a drive signal generator. The integrator generates a first signal responsive to integrating an input current of the power supply. The arithmetic operator generates a second signal responsive to the first signal and responsive to a ratio of a rectified input voltage to a dc output voltage of the power supply. The drive signal generator generates a drive signal in response to a delayed ramp signal and the second signal to control switching of the switch to provide power factor correction of the power supply and to provide a regulated current at the output.

Abstract: A controller for use in a power converter includes a drive circuit coupled to generate a drive signal to control switching of a power switch to control a transfer of energy from a power converter input to a power converter output. The controller also includes an input for receiving an enable signal including enable events responsive to the power converter output. The drive circuit is coupled to turn ON the power switch in response to the enable events and turn OFF the power switch in response to a power switch current reaching a current limit threshold. A current limit threshold generator is coupled to receive the drive signal from the enable events of the enable signal. The current limit threshold may be a ramp signal and the ramp signal along with the time between enable events may be used to modulate the drive signal.

Abstract: A power factor correction (PFC) controller includes a driver circuit coupled to vary the switching frequency of the power switch of the PFC converter in response to an input current of a PFC converter and an input voltage of the PFC converter, and to output a third signal to switch the power switch of the PFC converter to control the input current to substantially follow the input voltage. A frequency adjust circuit is coupled to receive an error voltage signal representative of an output of the PFC converter. The frequency adjust circuit is further coupled to output an adjusted error signal to adjust the end of the off time of the power switch of the PFC converter in response to the error voltage signal.

Abstract: A power factor correction (PFC) controller includes a capacitor, an error amplifier, a switching frequency adjuster, a comparator, and a drive signal generator. The current source generates a current that is representative of an instantaneous input voltage of a PFC converter to charge the capacitor when a power switch of the PFC converter is off. The switching frequency adjuster generates an adjusted error signal in response to an error signal generated by the error amplifier. The comparator compares a voltage on the capacitor with the adjusted error signal to generate a first signal to end an off time of the power switch. The drive signal generator controls switching of the power switch in response to the first signal. The switching frequency adjuster changes the adjusted error signal in response to changes in the error signal to adjust an average switching frequency of the power switch.

Abstract: A power converter controller includes a switch driver circuit coupled to generate a drive signal to control switching of a power switch to control a transfer of energy from an input of the power converter to an output of the power converter. An input sense circuit is coupled to receive an input sense signal representative of the input of a power converter. A sense enable circuit is coupled to receive the drive signal to generate a sense enable signal to control the input sense circuit in response to the drive signal. The sense enable signal is coupled to control the input sense circuit to sense the input sense signal continuously in response to a first load condition, and sense the input sense signal only during a fraction of a switching period of the power switch in response to a second load condition.

Abstract: A controller for use in a power converter includes a drive circuit coupled to generate a drive signal to control switching of a power switch to control a transfer of energy from a power converter input to a power converter output. The controller also includes an input for receiving an enable signal including enable events responsive to the power converter output. The drive circuit is coupled to turn ON the power switch in response to the enable events and turn OFF the power switch in response to a power switch current reaching a current limit threshold. A current limit threshold generator is coupled to receive the drive signal from the enable events of the enable signal. The current limit threshold may be a ramp signal and the ramp signal along with the time between enable events may be used to modulate the drive signal.

Abstract: An example on time control circuit for use in a power factor correction (PFC) controller includes an amplifier, an integrator, and a comparator. The amplifier generates an error signal that is representative of a difference between a feedback signal and a reference value. The integrator integrates a current sense signal that is representative of a current through the power switch to generate an integrator output signal. A gain of the integrator is varied in response to a voltage sense signal that is representative of a value of an input voltage of the PFC converter. The comparator generates a switch power off signal to terminate the on time of the power switch in response to comparing the integrator output signal with the error signal.

Abstract: An example power supply includes an energy transfer element, a switch, and a controller. The switch is coupled to the energy transfer element to control a transfer of energy from an input to a galvanically isolated output of the power supply. The controller includes a delayed ramp generator, an integrator, an arithmetic operator, and a drive signal generator. The integrator generates a first signal responsive to integrating an input current of the power supply. The arithmetic operator generates a second signal responsive to the first signal and responsive to a ratio of a rectified input voltage to a dc output voltage of the power supply. The drive signal generator generates a drive signal in response to a delayed ramp signal and the second signal to control switching of the switch to provide power factor correction of the power supply and to provide a regulated current at the output.

Abstract: A power factor correction (PFC) controller includes a capacitor, an error amplifier, a switching frequency adjuster, a comparator, and a drive signal generator. The current source generates a current that is representative of an instantaneous input voltage of a PFC converter to charge the capacitor when a power switch of the PFC converter is off. The switching frequency adjuster generates an adjusted error signal in response to an error signal generated by the error amplifier. The comparator compares a voltage on the capacitor with the adjusted error signal to generate a first signal to end an off time of the power switch. The drive signal generator controls switching of the power switch in response to the first signal. The switching frequency adjuster changes the adjusted error signal in response to changes in the error signal to adjust an average switching frequency of the power switch.

Abstract: An example on time control circuit for use in a power factor correction (PFC) controller includes an amplifier, an integrator, and a comparator. The amplifier generates an error signal that is representative of a difference between a feedback signal and a reference value. The integrator integrates a current sense signal that is representative of a current through the power switch to generate an integrator output signal. A gain of the integrator is varied in response to a voltage sense signal that is representative of a value of an input voltage of the PFC converter. The comparator generates a switch power off signal to terminate the on time of the power switch in response to comparing the integrator output signal with the error signal.

Abstract: A power factor correction (PFC) controller includes a first integrator coupled to integrate an input current of a PFC converter. A first signal is generated in response to the first integrator to end an on time of a power switch of the PFC converter. A second integrator is coupled to integrate a difference between a constant voltage and an input voltage of the PFC converter. A second signal is generated in response to the second integrator to end an off time of the power switch of the PFC converter. A driver circuit is coupled to vary the switching frequency of the power switch of the PFC converter in response to the first and the second signals and to output a third signal to switch the power switch of the PFC converter to control the input current to be substantially proportional to the input voltage.

Abstract: An example power factor correction (PFC) converter includes an energy transfer element, a power switch, and a controller. The controller includes an integrator and on/off logic. The integrator generates an integrator output signal in response to a voltage sense signal and a current sense signal. The on/off logic drives the power switch on and off to control a transfer of energy through the energy transfer element to an output of the PFC converter and terminates an on time of the power switch when the integrator output signal reaches a threshold value. A gain of the integrator is adjusted in response to the voltage sense signal such that the threshold value is substantially constant independent of the magnitude of the ac voltage source when a load condition at the output of the PFC converter is constant.

Abstract: A power factor correction (PFC) controller includes a first integrator coupled to integrate an input current of a PFC converter. A first signal is generated in response to the first integrator to end an on time of a power switch of the PFC converter. A second integrator is coupled to integrate a difference between a constant voltage and an input voltage of the PFC converter. A second signal is generated in response to the second integrator to end an off time of the power switch of the PFC converter. A driver circuit is coupled to vary the switching frequency of the power switch of the PFC converter in response to the first and the second signals and to output a third signal to switch the power switch of the PFC converter to control the input current to be substantially proportional to the input voltage.

Abstract: An example power factor correction (PFC) converter includes an energy transfer element, a power switch, and a controller. The controller includes an integrator and on/off logic. The integrator generates an integrator output signal in response to a voltage sense signal and a current sense signal. The on/off logic drives the power switch on and off to control a transfer of energy through the energy transfer element to an output of the PFC converter and terminates an on time of the power switch when the integrator output signal reaches a threshold value. A gain of the integrator is adjusted in response to the voltage sense signal such that the threshold value is substantially constant independent of the magnitude of the ac voltage source when a load condition at the output of the PFC converter is constant.