Abstract: A controller to regulate a power converter includes a terminal coupled to receive an enable signal including enable events representative of an output of the power converter. A drive circuit is 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 the output of the power converter. The drive circuit is coupled to turn on the power switch when an enable event is received in the enable signal. A current limit threshold generator is coupled to the drive circuit to generate a current limit threshold signal. The current limit threshold signal varies each switching cycle of the power switch. A time between consecutive enable events in the enable signal is the switching cycle of the power switch.

Abstract: A controller 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 control modulator is coupled to generate a first signal. A jitter modulator is coupled to generate a second signal. The second signal is a periodic signal having a modulation time period that is greater than a switching period of the drive signal. An arithmetic operator circuit is coupled to generate the modulated current limit signal in response to the first signal and the second signal.

Abstract: A method of providing an input switching request signal to an input side switch includes determining a switching request window indicative of relaxation ringing during a first switching cycle. It is determined that the input side switch is operating in a discontinuous conduction mode (DCM) mode of operation during a second switching cycle. It is determined that the switching request window is open during the second switching cycle. The input switching request signal is enabled in response to determining the switching request window is open.

Abstract: A power converter includes an energy transfer element that includes a primary winding and a secondary winding, and is coupled to transfer energy between the primary winding and the secondary winding. An enable circuit is coupled to generate an enable signal in response to a feedback signal falling below a threshold. A controller is coupled to control switching of a power switch coupled to the primary winding to regulate an output of the power converter. The controller includes a drive circuit coupled to output a drive signal in response to the enable signal, and a current limit threshold generator coupled to output a current limit threshold signal to the drive circuit in response to the drive signal. The current limit threshold signal varies in response to a time between events of the enable signal over a range of loads coupled to the output of the power converter.

Abstract: A circuit for use with a Universal Serial Bus (USB) socket includes a power converter coupled to receive an input voltage at an input terminal and coupled to provide an output voltage at an output terminal. A transistor is coupled between the output terminal of the power converter and a bus voltage terminal of the USB socket. A USB communication controller is coupled to the USB socket. The USB communication controller includes an output terminal coupled to a control terminal of the transistor. A bleeder circuit is coupled between the output terminal of the USB communication controller and the bus voltage terminal of the USB socket.

Abstract: A method for regulating a power converter includes initiating a transition of a switch coupled to an input side of the power converter from an OFF to an ON state to regulate a transfer of energy from the input to an output side of the power converter after a switch control signal generator receives an enable signal and if a feedback signal representative of an output of the power converter indicates a change in an output of the power converter. The enable signal is generated to communicate a control signal from the output to the input side in response to a first signal representative of a voltage on an output terminal that oscillates in response to an ending of the transfer of energy. The transition of the switch from the OFF to the ON state occurs substantially at a time that the first signal reaches an extremum.

Abstract: A circuit for use with a Universal Serial Bus (USB) socket includes a power converter coupled to receive an input voltage at an input terminal and coupled to provide an output voltage at an output terminal. A transistor is coupled between the output terminal of the power converter and a bus voltage terminal of the USB socket. A USB communication controller is coupled to the USB socket. The USB communication controller includes an output terminal coupled to a control terminal of the transistor. A bleeder circuit is coupled between the output terminal of the USB communication controller and the bus voltage terminal of the USB socket.

Abstract: A power converter includes a primary winding and multiple output windings to provide multiple independently controlled and regulated outputs with a common return line. The outputs are coupled to independently regulate constant current, constant voltage, or both constant current and constant voltage outputs. A secondary control block is coupled to control a synchronous rectifier switch coupled to the common return line to synchronize switching with a primary side power switch to provide complementary conduction of the primary winding and the multiple output windings. A plurality of controlled power pulse switches is coupled to the multiple output windings. A request of a power pulse from each of the outputs is transferred through the secondary control block to a primary switch control block to turn on the primary side power switch to transfer a power pulse to the multiple output windings and through controlled power pulse switches to the outputs.

Abstract: A power converter includes an energy transfer element that includes a primary winding and a secondary winding, and is coupled to transfer energy between the primary winding and the secondary winding. An enable circuit is coupled to generate an enable signal in response to a feedback signal falling below a threshold. A controller is coupled to control switching of a power switch coupled to the primary winding to regulate an output of the power converter. The controller includes a drive circuit coupled to output a drive signal in response to the enable signal, and a current limit threshold generator coupled to output a current limit threshold signal to the drive circuit in response to the drive signal. The current limit threshold signal varies in response to a time between events of the enable signal over a range of loads coupled to the output of the power converter.

Abstract: An ac-dc 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 generate a sense enable signal in response to the drive signal. The sense enable signal is coupled to control the input sense circuit to sense the input sense signal for an extended duration of time after the power switch turns OFF.

Abstract: A controller 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 control modulator is coupled to generate a first signal. A jitter modulator is coupled to generate a second signal. The second signal is a periodic signal having a modulation time period that is greater than a switching period of the drive signal. An arithmetic operator circuit is coupled to generate the modulated current limit signal in response to the first signal and the second signal.

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: A method for regulating a power converter includes initiating a transition of a switch coupled to an input side of the power converter from an OFF to an ON state to regulate a transfer of energy from the input to an output side of the power converter after a switch control signal generator receives an enable signal and if a feedback signal representative of an output of the power converter indicates a change in an output of the power converter. The enable signal is generated to communicate a control signal from the output to the input side in response to a first signal representative of a voltage on an output terminal that oscillates in response to an ending of the transfer of energy. The transition of the switch from the OFF to the ON state occurs substantially at a time that the first signal reaches an extremum.

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 controller for use in a power converter includes an initialization circuit coupled to a sense terminal coupled to an external resistor to receive a sense voltage from external resistor during a startup mode of the power converter. The sense terminal is coupled to sense an output current of the power converter after the startup mode of the power converter is complete. A decoder circuit is coupled to receive the sense voltage from the initialization circuit during the startup mode of the power converter. The decoder circuit is coupled to sense a voltage across an external resistor during the startup mode of the power converter to determine a value of the external resistor to set an operating parameter of the power converter in response to the value of the external resistor.

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 an initialization circuit coupled to a sense terminal coupled to an external resistor to receive a sense voltage from external resistor during a startup mode of the power converter. The sense terminal is coupled to sense an output current of the power converter after the startup mode of the power converter is complete. A decoder circuit is coupled to receive the sense voltage from the initialization circuit during the startup mode of the power converter. The decoder circuit is coupled to sense a voltage across an external resistor during the startup mode of the power converter to determine a value of the external resistor to set an operating parameter of the power converter in response to the value of the external resistor.

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 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: An ac-dc 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 generate a sense enable signal in response to the drive signal. The sense enable signal is coupled to control the input sense circuit to sense the input sense signal for an extended duration of time after the power switch turns OFF.