Abstract: A power converter controller includes a control loop clock generator that generates a switching frequency signal in response to a sense signal representative of a characteristic of the power converter, a load signal responsive to an output load, and a limit signal representative of a maximum length of a current half cycle of the switching frequency signal. A comparator generates an enable signal in response to the load signal and a load threshold. A limit control generates the limit signal in response to the enable signal and the switching frequency signal. A rate of change of half cycles of the switching frequency signal is controlled in response to the limit signal. A request transmitter generates a request signal in response to the switching frequency signal to control switching of a switching circuit coupled to the energy transfer element and an input of the power converter.

Abstract: A controller for use in a power converter includes a control loop clock generator that is coupled to generate a switching frequency signal in response to a sense signal representative of a characteristic of the power converter, a load signal responsive to an output load of the power converter, and a hard switch sense output. A hard switch sense circuit is coupled to generate the hard switch sense output in response to the switching frequency signal and a rectifier conduction signal that is representative of a polarity of an energy transfer element of the power converter. A request transmitter circuit is coupled to generate a request signal in response to the switching frequency signal to control switching of a switching circuit coupled to an input of the energy transfer element of the power converter.

Abstract: Methods and apparatus for continuous conduction mode operation in multi-output power converters are described herein. During a switching cycle, secondary current may be delivered via a diode to a secondary output. Prior to beginning a subsequent switching cycle, a diverting current may be provided to a lower voltage secondary output on a parallel path. In this way diode current may be reduced to substantially zero prior to the subsequent switching cycle.

Abstract: A controller to regulate an output voltage of a power converter comprising a feedback reference circuit to generate a drive signal to control a power switch in response to the feedback signal and an output power control circuit configured to generate an adjust signal in response to an output current of the power converter and a desired value of an output power of the power converter, the adjust signal adjusts the feedback signal such that the controller regulates the output voltage to achieve the desired value of the output power. The output power control circuit further comprises an analog-to-digital converter (ADC), a calculator circuit, and an update circuit. The ADC provides a measure signal which is a digital representation of the output current, the calculator circuit determines a calculated value of the output voltage, and the update circuit further outputs an update signal to update the adjust signal.

Abstract: An HFET includes a first and second semiconductor material. A first composite passivation layer includes a first insulation layer and a first passivation layer, and the first passivation layer is disposed between the first insulation layer and the second semiconductor material. The HFET includes a second passivation layer, where the first insulation layer is disposed between the first passivation layer and the second passivation layer. A gate dielectric is disposed between the second semiconductor material and the first passivation layer. A source electrode and a drain electrode are coupled to the second semiconductor material, and a gate electrode is disposed laterally between the source electrode and the drain electrode. A first gate field plate is disposed between the first passivation layer and the second passivation layer and electrically connected to the gate electrode, and a second gate field plate is disposed above first gate field plate.

Abstract: A controller for use in a power converter comprising a comparator, request control, and foldback control. The comparator configured to receive a feedback signal representative of an output of the power converter and a first regulation reference representative of a target value for the output, and in response to the comparison of the feedback signal and the first regulation reference, generate a first regulation signal. Request control configured to receive the first regulation reference, and output a request signal with request events. Foldback control configured to receive the first regulation signal to generate the first regulation reference, the foldback control further configured to sense a foldback or fault condition if the feedback signal is less than the first regulation reference for a threshold duration of time, the foldback control further configured to vary the first regulation reference in response to the sensed foldback or fault condition to reduce the output.

Abstract: A switch having a drain, a source, and a control. The switch comprising a depletion-mode transistor including a first, a second, and a control terminal and an enhancement-mode transistor including a first, a second, and a control terminal. The first terminal of the depletion-mode transistor is the drain of the switch and the control of the depletion-mode transistor is coupled to the source of the switch. The control of the enhancement-mode transistor is coupled to the control of the switch, the second terminal of the enhancement-mode transistor is the source of the switch. The switch comprises a clamp circuit to clamp a voltage of the first terminal of the enhancement-mode transistor to a threshold, the clamp circuit comprises a resistor and a pn-junction device coupled between the first and second terminals of the enhancement-mode transistor and between the second terminal and the control of the depletion-mode transistor.

Abstract: A resonant converter includes a resonant transformer having a leakage inductance and a magnetizing inductance coupled in series to form a resonant transformer input port. The resonant transformer has an output that is coupled to provide an output power to a load. A primary bridge circuit is coupled to provide an input power to the resonant transformer input port. A buffer circuit is coupled in parallel with the resonant transformer input port. A control module is coupled to receive a buffered primary port signal from the buffer circuit to control the primary bridge circuit to control the output power to the load in response to the buffered primary port signal.

Abstract: A controller for use with a power converter and a power switch comprising a primary controller and a secondary controller. The primary controller to control the power switch to transfer energy from the input side to the output side of the power converter. The secondary controller to transmit a control signal to the primary controller through a communication link, and to initiate a transition operation with the primary controller through the communication link. The secondary controller comprises a secondary switch control circuit configured to output the control signal in response to an output of the power converter, a charging circuit coupled to an energy storage element for providing power to the secondary control circuit, and a voltage detection circuit coupled to the energy storage element, wherein the voltage detection circuit is configured to indicate to the secondary switch control circuit when to initiate the transition operation.

Abstract: A method of enhancing a power factor during a half-line cycle of a power factor correction (PFC) converter includes generating an input voltage signal representative of a value of an input voltage of the PFC converter. A variable multiplication factor is adjusted to be greater than one for a first part of the half-line cycle and less than one for a second part of the half-line cycle. A pre-distortion signal is generated to be representative of the value of the input voltage of the PFC converter times the variable multiplication factor. An input current of the PFC converter is sensed. A first signal is generated in response to a sensed input current of the PFC converter multiplied by the pre-distortion signal. An on-time of a switch of the PFC converter is ended in response to the first signal.

Abstract: A power converter comprising an energy transfer element is coupled between an input of the power converter and an output of the power converter. A cascode circuit generates a first sense signal and a second sense signal. A controller controls the switching of the cascode circuit to transfer energy from the input of the power converter to the output of the power converter. The controller comprising a current sense circuit generates a current limit signal and an overcurrent signal in response to the first sense signal and the second sense signal. A control circuit generates a control signal in response to the current limit signal and the overcurrent signal. A drive circuit comprising a first stage gate drive circuit generates a drive signal in response to the control signal to reduce EMI, and a second stage of gate drive circuit to enable accurate current sensing of the cascode circuit.

Abstract: A controller for use in a power converter including a jitter generator circuit coupled to receive a drive signal from a switch controller and generate a jitter signal. The jitter signal is a modulated jitter signal when the drive signal is below a first threshold frequency. The switch controller is 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 current through the power switch. The switch controller is coupled to generate the drive signal to control switching of the power switch in response to the current sense signal and the jitter signal to control a transfer of energy from an input of the power converter to an output of the power converter.

Abstract: A controller configured for use with a power converter and a power switch comprising a primary controller coupled to the power converter and configured to provide a switch drive signal to control switching of the power switch to transfer energy from a primary side to a secondary side of the power converter. A primary switching pattern circuit is configured to provide a primary switching pattern to operate the primary controller in a first mode of operation and a primary switch control circuit is coupled to the primary switching pattern circuit and configured to receive a control signal representative of turn-on of the power switch, to receive the primary switching pattern, and to output the switch drive signal. The primary switch control circuit operates in a first mode, a second mode, and a transition, wherein the primary switch control circuit operates in the second mode after the transition has been completed.

Abstract: A controller for use in a power converter comprising a comparator, request control, and foldback control. The comparator configured to receive a feedback signal representative of an output of the power converter and a first regulation reference representative of a target value for the output, and in response to the comparison of the feedback signal and the first regulation reference, generate a first regulation signal. Request control configured to receive the first regulation reference, and output a request signal with request events. Foldback control configured to receive the first regulation signal to generate the first regulation reference, the foldback control further configured to sense a foldback or fault condition if the feedback signal is less than the first regulation reference for a threshold duration of time, the foldback control further configured to vary the first regulation reference in response to the sensed foldback or fault condition to reduce the output.

Abstract: Apparatus and methods for sensing a variable amplitude switching signal from a secondary winding in a power conversion system are disclosed herein. By using a comparator with an adaptable reference, variable amplitude secondary winding signals in phase with primary winding signals may be detected in the presence of ringing. Detection of the in phase secondary winding signals, in turn, allows for secondary side control with power factor correction and discontinuous mode operation.

Abstract: A controller for use in a power converter comprising a request control circuit coupled to receive a feedback signal representative of an output of the power converter. The request control circuit is coupled to generate a request signal for controlling a power switch. The request signal can include a synchronization signal in response to the feedback signal and a jitter average signal. The synchronization signal is generated by the request transmitter circuit and corresponds to an average on time for controlling the power switch.

Abstract: A turn-off circuit for a semiconductor switch includes an element having a variable resistance coupled to a control input of the semiconductor switch, a circuit for generating a control-input reference signal, and a control circuit coupled to adjust a resistance of the element having a variable resistance in response to the control-input reference signal in a closed control loop in order to turn off the semiconductor switch.

Abstract: A method of forming one or more contact regions in a high-voltage field effect transistor (HFET) includes providing a semiconductor material, including a first active layer and a second active layer, with a gate dielectric disposed on a surface of the semiconductor material. A first contact to the semiconductor material is formed that extends through the second active layer into the first active layer, and a passivation layer is deposited, where the gate dielectric is disposed between the passivation layer and the second active layer. An interconnect is formed extending through the first passivation layer and coupled to the first contact. An interlayer dielectric is deposited proximate to the interconnect, and a plug is formed extending into the interlayer dielectric and coupled to the first portion of the interconnect.

Abstract: A driver circuit for use in a controller includes a signal generator coupled to generate a first control signal and a second control signal in response to a drive signal that is coupled to control switching of a secondary switch that is to be coupled to the driver circuit and referenced to a reference voltage that is greater than a ground reference voltage. A second switch is coupled to be controlled by the second control signal such that the reference voltage is substantially applied to a control of the secondary switch when the drive signal controls the secondary switch to be off. A first switch is coupled to be controlled by the first control signal such that the sum of the reference voltage and a first voltage is substantially applied to the control of the secondary switch when the drive signal controls the secondary switch on.

Abstract: A power converter includes an energy transfer element coupled between an input of the power converter and an output of the power converter. A control switch is coupled to a normally-on switch. The normally-on switch is coupled to the energy transfer element. A controller is coupled to control switching of the control switch to control a transfer of energy from the input of the power converter to the output of the power converter. The controller includes a drive circuit coupled to generate a drive signal in response to a control signal to control switching of the control switch. The drive signal in a first stage of a multiple stage gate drive is coupled not to fully enhance the control switch. The drive signal provided by a second stage of the multiple stage gate drive is coupled to fully enhance the control switch.