Power Integrations, Inc.

Kent Wong

Alex B Djenguerian

Balu Balakrishnan

David Michael Hugh Matthews

Stefan Bäurle

Arthur Brian Odell

Andrew John Morrish

Chan Woong Park

Zhao-Jun Wang

Erdem Bircan

William B Smith

Robert J Mayell

Stefan B&amacr;urle

Wang Zhao-Jun

A circuit for regulating an output level of a power converter includes an adjustment circuit to be coupled to a receive a feedback signal representative of an output level of the power converter. The adjustment circuit is coupled to generate a comparison result signal. A control circuit is coupled to receive the comparison result signal and an oscillating signal. A switch including a first terminal, a second terminal and a control terminal is coupled to the control circuit. The control circuit is coupled to generate a control signal to control switching of the switch. The switch is operable to couple or decouple the first terminal and the second terminal in response to the control signal received at the control terminal. The control signal is responsive to the oscillating signal and to a change in the comparison result signal.

Method and apparatus for digital control of a switching regulator

An on/off controller device includes a control circuit to generate a control signal to switch a power switch between an on state and an off state to transfer energy from a primary side to a secondary side of a switched mode power supply. A comparator is coupled to generate an enable signal that enables and disables the switching of the power switch by the control circuit. The comparator compares a feedback signal with a variable threshold and switches the enable signal between enabling and disabling the switching of the power switch. The variable threshold is modulated to increase a fundamental frequency of the switching of the power switch by the control circuit. The variable threshold is modulated with a fixed amplitude pulse that is combined with a second threshold to modulate the variable threshold between a first higher value and a second lower value.

An example integrated control circuit includes a regulator, a first comparator, a second comparator, and a counter. The regulator is to charge, during a time period, a capacitor. The first comparator is to provide an output indicating when a voltage on the capacitor reaches a first threshold voltage. The second comparator is coupled to provide an output indicating when the voltage on the capacitor reaches a second threshold voltage. The counter is coupled to begin counting in response to the first threshold voltage being reached and is coupled to stop counting in response to the second threshold voltage being reached. The counter is coupled to provide an output representative of the capacitance value of the capacitor during the time period and the integrated control circuit receives a bias current at the terminal from the capacitor to provide power to operate the integrated control circuit after the time period has ended.

Method and apparatus to select a parameter/mode based on a time measurement

One controller for a power supply includes an oscillator, a first circuit, a counter, and a pause circuit. The first circuit generates a drive signal to control switching of a switch to regulate an output of the power supply. The first circuit initiates an on time period of the switch in response to both a clock signal of the oscillator and an enable signal that is generated in response to a feedback signal of the power supply. The counter receives the enable signal and generates an output signal when the counter reaches a count value indicating that the enable signal has been idle for an amount of time. The pause circuit generates a pause signal in response to the output signal of the counter. The oscillator is paused in response to the pause signal and a maximum on time period of the switch is extended while the oscillator is paused.

Method and apparatus for increasing the power capability of a power supply

In one aspect, a power supply includes an energy transfer element, a switch, a feedback circuit, a comparator, a state machine, and a control circuit. The feedback circuit generates a feedback signal representative of an output level of the power supply. The comparator provides a feedback state signal having a first feedback state that represents the output level of the power supply being above a threshold level and a second feedback state that represents the output level being below the threshold level. The state machine selectively modulates a first signal in response to the feedback state signal, where the first signal is the feedback signal or the threshold value signal. The control circuit is coupled to control switching of the switch to regulate the output level of the power supply in response to the feedback state signal.

A power supply includes an energy transfer element, a switch, and a controller. The controller includes a modulator, a drive signal generator, a comparator, and a variable current limit generator. The modulator generates an enable signal having logic states responsive to a feedback signal. The drive signal generator either enables or skips enabling a switch of the power supply during a switching period in response to the logic state of the enable signal. The comparator asserts an over current signal to disable the switch if the switch current exceeds a variable current limit. The variable current limit generator sets the variable current limit to a first current limit in response to one logic state of the enable signal and sets the variable current limit to a second current limit if the enable signal transitions logic states and the over current signal is asserted during the switching period.

Method and apparatus to limit output power in a switching power supply

A power supply includes an energy transfer element coupled between an input and an output. A switch is coupled to an input of the energy transfer element. A threshold detection circuit includes in an integrated circuit coupled to measure a signal from a resistive external circuit coupled between fourth and first external terminals of the integrated circuit during an initialization period after the fourth external terminal has been charged to a supply threshold value. A regulator circuit is coupled between second and fourth external terminals of the integrated circuit. The regulator circuit is coupled to charge the fourth external terminal to the supply threshold value during the initialization period. A selection circuit is coupled to the threshold detection circuit to select a parameter/mode of the integrated circuit in response to the measured signal.

Method and apparatus to select a parameter/mode based on a measurement during an initialization period

One example controller for a power supply includes an oscillator, a drive signal generator, and a restart circuit. The oscillator generates a clock signal and the drive signal generator controls switching of a switch to regulate an output of the power supply in response to the clock signal. The restart circuit generates a restart signal in response to a current through the switch and in response to an absolute maximum on time period. The oscillator generates the clock signal to have a fixed maximum frequency in response to the restart signal indicating that the current through the switch reaches a current limit threshold within the absolute maximum on time period. The oscillator also generates the clock signal to have a variable minimum frequency in response to the restart signal indicating that the current through the switch has not reached the current limit threshold within the maximum on time period.

A method and apparatus of reducing peak current variation with changing input line voltage in a switch mode power supply is disclosed. An example method includes sensing a current through a switching device of the switch mode power supply. A variable current limit threshold is generated, which increases from a first level to a second level during an on time of the switching device. The current is compared to the variable current limit threshold. A feedback signal representative of an output voltage of the switch mode power supply is sensed. The switching device is controlled in response to the feedback signal and said comparing the current to the variable current limit threshold.

Method and apparatus for maintaining a constant load current with line voltage in a switch mode power supply

An integrated circuit includes a threshold detection circuit that is coupled to measure a signal from a first resistive external circuit coupled between a fourth external terminal of the integrated circuit and a first external terminal of the integrated circuit during a duration of an initialization period after the fourth external terminal has been charged to a supply threshold value. A regulator circuit is coupled to charge the fourth external terminal to the supply threshold value during the initialization period of the integrated circuit. A selection circuit is coupled to the threshold detection circuit to select a parameter/mode of the integrated circuit in response to the signal measured from the first resistive external circuit during the duration of the initialization period after the fourth external terminal has been charged to the supply threshold value.

In one aspect, a power supply regulator includes a feedback terminal, a node, a control circuit, a first current source, and a second current source. The node is coupled to the feedback terminal to provide a feedback state signal in response to a feedback current through the feedback terminal. The feedback state signal has feedback states that represent an output of the power supply. The control circuit is to be coupled to a power switch and to receive the feedback state signal to regulate the output of the power supply. The first current source is coupled to the node to provide a first current to the node. The second current source is coupled to the node to selectively remove a second current from the node to modulate the feedback current and to alter the feedback state of the feedback state signal.

An example integrated circuit controller for a power supply includes a modulator, a drive signal generator, a comparator, and a variable current limit generator. The modulator generates an enable signal having logic states responsive to a feedback signal. The drive signal generator either enables or skips enabling a switch of the power supply during a switching period in response to the logic state of the enable signal. The comparator asserts an over current signal to disable the switch if current flowing through the switch exceeds a variable current limit. The variable current limit generator sets the variable current limit to a first current limit in response to one logic state of the enable signal during a switching period and sets the variable current limit to a second current limit if the enable signal transitions logic states and the over current signal is asserted during the switching period.

Techniques are disclosed to extend an on time period of switch to regulate a transfer of energy from an input of a power supply to an output of a power supply. One example integrated circuit includes an energy transfer element coupled between an input and an output of the power supply. A switch is coupled to the input of the energy transfer element. A controller is coupled to the switch to control switching of the switch to regulate a transfer of energy from the input of the power supply to the output of the power supply in response to a feedback signal received from the output of the power supply. The controller is coupled to limit a maximum on time period of the switch a first maximum on time period in response to a first range of power supply operating conditions and to a second maximum on time period for a second range of power supply operating conditions.

Techniques are disclosed to select functional parameters and/or operating modes of a circuit based on a measurement during an initialization period. In one aspect an integrated circuit includes a threshold detection circuit coupled to measure during an initialization period of the integrated circuit a signal from a first external circuit comprising one or more components coupled to a first external terminal of the integrated circuit. A selection circuit is coupled to the threshold detection circuit to select a parameter/mode of the integrated circuit in response to the signal from the first external circuit during the initialization period of the integrated circuit. The first external terminal is further coupled to one or more additional external circuits, each of which comprising one or more components. The one or more additional external circuits are coupled to provide one or more signals at the first external terminal to be used by the integrated circuit during normal operation at times other than the initialization period to provide at least one additional function for the integrated circuit after the initialization period of the integrated circuit is complete.

A power supply regulator including a variable current limit threshold that increases during an on time of a switch. In one aspect, a power supply regulator includes a comparator coupled to receive a signal representative of a current through a switch during an on time of the switch. The comparator is further coupled to receive a variable current limit threshold that increases during the on time of the switch. The power supply regulator also includes a feedback circuit coupled to receive a feedback signal representative of an output of a power supply. A control circuit is also included and is coupled to the switch, to an output of the comparator, and to an output of the feedback circuit. The control circuit is coupled to control a switching of the switch in response the output of the comparator and the output of the feedback circuit to regulate the output of the power supply.

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Fremont, CA, United States of America

Kent Wong