Abstract: One embodiment includes a power supply system including a transformer comprising a primary, secondary, and auxiliary winding that are magnetically coupled. The system also includes a switch stage that generates a current through the primary winding in response to activation of a switch based on a control signal that is generated based on a feedback voltage associated with the auxiliary winding. The current can be induced in the secondary winding. The system also includes an output stage coupled to the secondary winding and that generates an output voltage based on the current induced in the secondary winding. The system further includes a feedback stage coupled to the auxiliary winding and comprising a discriminator configured to determine a zero-current condition associated with the current induced in the auxiliary winding based on monitoring a change in slope of the feedback voltage and to measure the feedback voltage during the zero-current condition.

Abstract: One embodiment includes a power supply system including a transformer comprising a primary, secondary, and auxiliary winding that are magnetically coupled. The system also includes a switch stage that generates a current through the primary winding in response to activation of a switch based on a control signal that is generated based on a feedback voltage associated with the auxiliary winding. The current can be induced in the secondary winding. The system also includes an output stage coupled to the secondary winding and that generates an output voltage based on the current induced in the secondary winding. The system further includes a feedback stage coupled to the auxiliary winding and comprising a discriminator configured to determine a zero-current condition associated with the current induced in the auxiliary winding based on monitoring a change in slope of the feedback voltage and to measure the feedback voltage during the zero-current condition.

Abstract: Apparatus and methods disclosed herein are associated with a primary side voltage and/or current regulator (PSR) in a flyback power converter. Apparatus and methods sense characteristics of a waveform generated in an auxiliary primary winding of a flyback transformer at a single terminal of the PSR. The waveform is analyzed, and error signals derived therefrom are used to maintain constant voltage and/or constant current regulation and to generate a peak current stabilization signal that is independent of line input voltage.

Abstract: A switching power supply includes a transformer having a primary side and a secondary side. The primary side is coupled to a switch for controlling current flow through the primary side and the secondary side generates an output voltage. A controller controls switching of the switch to generate a first power level on the secondary side of the transformer when the power supply is in a stand-by mode and a second power level when the power supply is in an active mode. A monitor samples the output voltage, generates a reference voltage, and generates a wake up signal in response the output voltage being less than the reference voltage. The controller controls the switch in response to the wake up signal to generate the first power level.

Abstract: One embodiment includes a power supply system including a transformer comprising a primary, secondary, and auxiliary winding that are magnetically coupled. The system also includes a switch stage that generates a current through the primary winding in response to activation of a switch based on a control signal that is generated based on a feedback voltage associated with the auxiliary winding. The current can be induced in the secondary winding. The system also includes an output stage coupled to the secondary winding and that generates an output voltage based on the current induced in the secondary winding. The system further includes a feedback stage coupled to the auxiliary winding and comprising a discriminator configured to determine a zero-current condition associated with the current induced in the auxiliary winding based on monitoring a change in slope of the feedback voltage and to measure the feedback voltage during the zero-current condition.

Abstract: One embodiment includes a power supply system including a transformer comprising a primary, secondary, and auxiliary winding that are magnetically coupled. The system also includes a switch stage that generates a current through the primary winding in response to activation of a switch based on a control signal that is generated based on a feedback voltage associated with the auxiliary winding. The current can be induced in the secondary winding. The system also includes an output stage coupled to the secondary winding and that generates an output voltage based on the current induced in the secondary winding. The system further includes a feedback stage coupled to the auxiliary winding and comprising a discriminator configured to determine a zero-current condition associated with the current induced in the auxiliary winding based on monitoring a change in slope of the feedback voltage and to measure the feedback voltage during the zero-current condition.

Abstract: Apparatus and methods disclosed herein are associated with a primary side voltage and/or current regulator (PSR) in a flyback power converter. Apparatus and methods sense characteristics of a waveform generated in an auxiliary primary winding of a flyback transformer at a single terminal of the PSR. The waveform is analyzed, and error signals derived therefrom are used to maintain constant voltage and/or constant current regulation and to generate a peak current stabilization signal that is independent of line input voltage.

Abstract: A system and method for managing phases in a multiphase switching power supply turns off a phase in light load conditions and turns on a phase in heavier load conditions. The increase or decrease in the number of phases changes the efficiency of the power supply in response to operating conditions. The phases of the power supply may be synchronized and interleaved. Input current or power representing power supply loading provides a criteria for switching phases on or off. The input current can be taken from an input current sense resistor. The input power can be determined based on a control for managing phases. Turning a phase off causes remaining phases to have an increased on-time or gain to smooth the transition between differing numbers of active phases.

Abstract: A system and method for power conversion synchronizes multiple phases at a desired phase angle difference. The power conversion involves variable frequency switching, fixed on-time and provides power factor correction. A relative measure of a phase angle difference between two phases permits each phase to be controlled to obtain the desired phase angle difference. The power conversion involves transition mode switching to help reduce switching losses. A phase angle difference detector may be provided for each phase. The various phases may have different inherent frequencies that vary with switching frequency, and are synchronized to an average frequency. Current measures can be taken with a single component, such as a resistor. A maximum frequency control limits period width to avoid high frequency switching. An added switch on time improves input voltage crossover distortion. One or more phases can be deactivated in light load conditions.

Abstract: A system and method for power conversion synchronizes multiple phases at a desired phase angle difference. The power conversion involves variable frequency switching, fixed on-time and provides power factor correction. A relative measure of a phase angle difference between two phases permits each phase to be controlled to obtain the desired phase angle difference. The power conversion involves transition mode switching to help reduce switching losses. A phase angle difference detector may be provided for each phase. The various phases may have different inherent frequencies that vary with switching frequency, and are synchronized to an average frequency.

Abstract: A system and method for synchronizing an oscillator with multiple phases at a desired phase angle difference. A relative measure of a phase angle difference between two phases permits each phase to be controlled to obtain the desired phase angle difference. The various phases may have different inherent frequencies that are synchronized to a common frequency such as an average of the different frequencies.

Abstract: A system and method for managing phases in a multiphase switching power supply turns off a phase in light load conditions and turns on a phase in heavier load conditions. The increase or decrease in the number of phases changes the efficiency of the power supply in response to operating conditions. The phases of the power supply may be synchronized and interleaved. Input current or power representing power supply loading provides a criteria for switching phases on or off. The input current can be taken from an input current sense resistor. The input power can be determined based on a control for managing phases. Turning a phase off causes remaining phases to have an increased on-time or gain to smooth the transition between differing numbers of active phases.

Abstract: A system and method for power conversion synchronizes multiple phases at a desired phase angle difference. The power conversion involves variable frequency switching, fixed on-time and provides power factor correction. A relative measure of a phase angle difference between two phases permits each phase to be controlled to obtain the desired phase angle difference. The power conversion involves transition mode switching to help reduce switching losses. A phase angle difference detector may be provided for each phase. The various phases may have different inherent frequencies that vary with switching frequency, and are synchronized to an average frequency.

Abstract: A system and method for power conversion synchronizes multiple phases at a desired phase angle difference. The power conversion involves variable frequency switching, fixed on-time and provides power factor correction. A relative measure of a phase angle difference between two phases permits each phase to be controlled to obtain the desired phase angle difference. The power conversion involves transition mode switching to help reduce switching losses. A phase angle difference detector may be provided for each phase. The various phases may have different inherent frequencies that vary with switching frequency, and are synchronized to an average frequency. Current measures can be taken with a single component, such as a resistor. A maximum frequency control limits period width to avoid high frequency switching. An added switch on time improves input voltage crossover distortion. One or more phases can be deactivated in light load conditions.

Abstract: A current-limiting circuit providing a foldback limiting action which is compensated for the temperature coefficient of the sensing resistor. Temperature compensation and voltage-related signals are combined with a multiplier circuit providing a multiplier output which is compared to the voltage developed across the sense resistor to produce a current control or current limiting indicating signal. One embodiment of the present invention is implemented in a monolithic integrated circuit including an aluminum sense resistor, and the temperature compensation selected to substantially eliminate the effects of the temperature coefficient of the aluminum sense resistor, resulting in a more stable foldback current limiting characteristic over an extended temperature range.

Abstract: An adjustable threshold window circuit having low-input bias current and constant percentage threshold hysteresis. The window circuit defines an upper reference voltage and a lower reference voltage, both simultaneously adjusted from a common signal wherein the upper threshold voltage increases as the lower voltage threshold decreases to define a voltage window. The threshold voltages are received by a comparator circuit which receives signals to be compared to the upper and lower voltage references, and provides an overvoltage and undervoltage fault indication when the received signals exceed the respective thresholds. Theovervoltage and undervoltage fault signals are received by the window circuit, providing an adjustment of the reference voltages to produce a hysteresis effect.

Abstract: A multiple input window comparator for use in apparatus requiring sensing of a voltage window, such as power supplies and system monitors, including a first comparator having multiple input transistors, each of which receives a signal to be compared. The comparator characteristics for each input signal are balanced through the use of a current mirror circuit connected to each input transistor. A complementary second comparator circuit is provided which, in combination with the first comparator circuit, produces a signal indicating when one or more of the input signals exceeds the voltage boundaries (voltage window) defined by reference signals of the first and second comparator. The circuit topology of each of the first and second comparators produces a zero input voltage offset with respect to the respective reference voltage, such that the comparator output signal occurs substantially instantaneously and uniformly with the transition of the threshold voltage by one or more of the input signals.

Abstract: An analog integrated filter circuit includes a capacitance multiplier combined with a DC bias controlled current circuit designed to render the filter circuit insensitive to changes in the parameter values of the components caused by process variations or a temperature change therein. The capacitance multiplier circuit includes grounded or ungrounded capacitance multipliers in different combinations operatively coupled to the DC bias controlled current circuit so that the capacitance multiplier circuit can be used to construct a predictable low pass, bandpass or high pass filter circuit with frequency characteristics that do not vary over temperature.