Abstract: System and method for regulating an output voltage of a power conversion system. The system includes an error amplifier coupled to a capacitor. The error amplifier is configured to receive a reference voltage, a first voltage, and an adjustment current and to generate a compensation voltage with the capacitor. The first voltage is associated with a feedback voltage. Additionally, the system includes a current generator configured to receive the compensation voltage and generate the adjustment current and a first current, and a signal generator configured to receive the first current and a second current. The signal generator is further configured to receive a sensing voltage and to generate a modulation signal. Moreover, the system includes the gate driver directly or indirectly coupled to the signal generator and configured to generate a drive signal based on at least information associated with the modulation signal.

Abstract: A dual-switch flyback power converter includes a control circuit to generate a switching signal. A high-side driving circuit includes a pulse generation circuit. The pulse generation circuit generates a pulse-on signal and a pulse-off signal to control two transistors in response to the switching signal. The two transistors further respectively provide a level-shift-on signal and a level-shift-off signal to a comparison circuit to enable/disable a high-side driving signal. Without using a charge pump circuit to power the high-side driving circuit, a floating winding of a transformer is utilized to provide a floating voltage to power the high-side driving circuit, which reduces the cost of the dual-switch flyback power converter and ensures a sufficient high-side driving capability of the high-side driving circuit.

Abstract: An embodiment of a self-supply circuit, for a voltage converter that converts an input voltage into an output voltage and has a main switch and a controller, designed to control switching of the main switch for controlling the output voltage; the self-supply circuit is provided with: a charge accumulator, which is connected to the controller and supplies a self-supply voltage to the same controller; a generator, which supplies a charge current to the charge accumulator; and an auxiliary switch, which has a first conduction terminal in common with a respective conduction terminal of the main switch and is operable so as to control transfer of the charge current to the charge accumulator. In particular, the self-supply circuit is provided with a precharge stage, connected to the auxiliary switch, which carries out a precharging of an intrinsic capacitance of the auxiliary switch before a turning-off transient of the main switch ends.

Abstract: Switch mode power converter system and method thereof. The system includes one or more isolation boxes including at least a first isolation box, an input primary winding for receiving an input signal for the switch mode power converter system, and an output secondary winding for generating an output signal for the switch mode power converter system. The switch mode power converter system is configured to convert the input signal to the output signal. One of the input primary winding and the output secondary winding is substantially enclosed in the first isolation box, and the other of the input primary winding and the output secondary winding is not enclosed in the first isolation box. The first isolation box is conductively connected to a constant-voltage source.

Abstract: In one embodiment, a switch mode power supply comprising a switch and a control circuit is disclosed. The control circuit may comprise a multi-function pin configured to receive a first current sampling signal and a first voltage sampling signal. A first comparing signal may be provided by comparing the first voltage sampling signal with a first threshold signal when the switch is turned OFF, and a second comparing signal may be provided by comparing the first current sampling signal with a second threshold signal when the switch is turned ON. The control circuit may be configured to control the switch in accordance with the first comparing signal and the second comparing signal.

Abstract: A single-stage integrated circuit drives LED sources in a constant power mode to eliminate the need for LED current sensing, while reshaping the waveform of the inductor current near line zero crossing to achieve high power factor. The integrated circuit achieves substantially constant input power by maintaining a constant voltage at a power factor corrector controller through an input voltage feedforward system. Accordingly, the disclosed circuit provides a high power factor, high efficiency, simple, and cost-effective solution with substantially consistent input power for both isolated and non-isolated offline LED applications.

Abstract: Switching-mode power conversion system and method thereof. The system includes a primary winding configured to receive an input voltage, an a secondary winding coupled to the primary winding and configured to, with one or more first components, generate, at an output terminal, an output voltage and an output current. Additionally, the system includes an auxiliary winding coupled to the secondary winding and configured to, with one or more second components, generate, at a first terminal, a detected voltage. Moreover, the system includes an error amplifier configured to receive the detected voltage and a first reference voltage and generate an amplified voltage based on at least information associated with a difference between the detected voltage and the first reference voltage. Also, the system includes a compensation component configured to receive the amplified voltage and generate a second reference voltage based on at least information associated with the amplified voltage.

Abstract: An isolated primary circuit regulator is applied to a primary side of a transformer of a power supply. The isolated primary circuit regulator outputs a switching signal, and switches the transformer by using the switching signal, thereby stabilizing an output current. The isolated primary circuit regulator includes a discharge time detector, an oscillator, a pulse width modulator and a control circuit. The discharge time detector is used for detecting a discharge time of a switching current generated at a secondary side of the transformer. The oscillator is used for generating an oscillation signal. The control circuit is used for outputting an adjustment signal. The pulse width modulator outputs a switching signal according to the oscillation signal output by the oscillator and the adjustment signal output by the control circuit. The switching signal has a duty cycle and a frequency corresponding to the oscillation signal and the adjustment signal.

Abstract: A converter controller is disclosed. In one embodiment, a controller for a flyback converter includes a converter and a flyback controller. The converter is coupled to the flyback converter for receiving an auxiliary voltage and for generating a constant power voltage. The flyback controller is powered by the constant power voltage for controlling an output voltage of the flyback converter. Furthermore, the flyback converter comprises a transformer with a primary side and a secondary side. The output voltage and the auxiliary voltage are produced at the transformer.

Abstract: A controller of an AC/DC flyback switching power supply uses adaptive digital control approaches to control the switching operation of a BJT power switch based on primary-side feedback to regulate the secondary-side constant output voltage and output current, without using the input line voltage. Switching-cycle by switching-cycle peak current control and limit are achieved based on the sensed primary-side current rather than the input line voltage in both constant-voltage and constant-current modes, operating in PWM, PFM and/or combinations of a plurality of PWM and PFM modes. The controller IC does not need a separate pin and ADC circuitry for sensing the input line voltage. The controller IC directly drives the BJT base, and dynamically adjusts the BJT base current amplitude cycle by cycle based on load change.

Abstract: A drive system has a low voltage system, a high voltage system, and a transformer. The high voltage system has drive units which correspond to power switching elements. A capacitance in the high voltage system serves as a flouting power source which supplies electric power to each of the drive units. An output voltage of a secondary side coil of the transformer is supplied to the capacitance. A comparator compares the output voltage at the secondary side coil of the transformer with a threshold value. A switching speed change part changes the switching speed of each of the power switching element based on the comparison result of the comparator.

Abstract: An output regulation circuit of a power converter without current sensing loss includes a transforming circuit to receive a proportional voltage from the primary winding of the power converter during the on-time period of the power switch. The first proportional voltage is transformed to a charging current signal to charge an energy storage device. Thus, the circuit controls the power switch according to a voltage limited signal of the energy storage device.

Abstract: The present invention includes a voltage clamping circuit 6 for outputting a voltage signal, which has been clamped to a predetermined voltage, from the drain voltage of a switching element 1, and a turn-on detection circuit 7 for detecting the turn-on timing of the switching element 1 from the voltage signal. Thus it is possible to turn on the switching element 1 at the minimum value of the drain voltage without adding external terminals.

Abstract: A discontinuous mode flyback converter for limiting output current using primary feedback is disclosed. A transformer stores magnetic energy using field current and transfers the magnetic energy using a primary winding and a secondary winding closely coupled to the primary winding. A switching element is coupled to one end of the primary winding of the transformer and controls the current of the primary winding of the transformer. A control unit controls the switching element. A voltage error feedback unit feeds back the error of the output voltage of the transformer to the control unit, thereby regulating the output voltage. An output current feedback circuit detects the flyback period of the transformer, detects the output current information of the transformer from the rate of a flyback period in a cycle, and feeds it back to the control unit, thereby limiting the output current of the transformer.

Abstract: An example power converter includes an energy transfer element, a switch, a controller, and a current offset circuit. The controller switches the switch between an ON state and an OFF state to regulate the output of the power converter and is adapted to terminate the ON state of the switch in response to a switch current flowing through the switch reaching a switch current threshold. The current offset circuit is coupled to the input to be directly powered from an input voltage of the power supply. The current offset circuit generates an offset current to flow through the switch only during the ON state of the switch in response to a magnitude of the input voltage. The input current of the power converter is adjusted in response to the offset current.

Abstract: A controller that forces primary regulation is disclosed. An example controller includes a switched element to be coupled to a second winding of an energy transfer element of a power supply. A secondary control circuit is coupled to the switched element. The secondary control circuit is to be coupled across an output of the second winding to switch the switched element in response to a difference between an actual output value at the output of the second winding and a desired output value to force a current in a third winding of the energy transfer element that is representative of the difference between the actual output value at the output of the second winding and the desired output value. A primary switch is to be coupled to a first winding of the energy transfer element. A primary control circuit is coupled to the primary switch. The primary control circuit is to be coupled to receive the current forced in the third winding of the energy transfer element in response to the secondary control circuit.

Abstract: A single-stage AC to DC conversion device includes an energy storage unit, a magnetic unit, and a switch unit. The magnetic unit electrically connects the energy storage unit with the switch unit, and has a core, a first winding, a second winding, a third winding, and at least one output winding. The first winding couples with the core and transfers a first electric energy to the core. The second winding couples with the core and stores a second electric energy in the energy storage unit. The third winding couples with the core and transfers the second electric energy to the core. The output winding couples with the core that transfers the first electric energy and the second electric energy, and outputs a third electric energy through the output winding.

Abstract: A flyback DC-DC converter is disclosed herein. The flyback DC-DC converter includes a controller, an input switching circuit, a transformer and an output switching circuit. The input switching circuit is controlled by the controller and thus controls power supply to the transformer. The transformer is equipped with a first secondary winding to provide the output voltage, a second secondary winding that forms a feedback loop together with a voltage divider, and a third secondary winding to control the output switching circuit.

Abstract: A switching voltage regulator samples signals corresponding to a flyback voltage on an auxiliary winding on a primary side of the switching voltage regulator. The flyback voltage functions as feedback from the output voltage on the secondary side. On detection of presence of the flyback voltage, samples corresponding to the flyback voltage are stored until the flyback voltage falls below a threshold voltage. A history of N samples of the flyback voltage is thus maintained. A sample older than the most recently stored sample is used to generate control for generation of the output voltage of the switching voltage regulator. Use of the older sample ensures that the flyback voltage sample used is one that is close to, but before the current in the secondary winding goes to zero.

Abstract: An example power supply controller includes a switch duty cycle controller coupled to receive a feedback signal and a duty cycle adjust signal. The switch duty cycle controller is coupled to generate a drive signal coupled to control switching of a switch, which is coupled to an energy transfer element, to regulate energy delivered from an input of a power supply to an output of the power supply. The power supply controller also includes a gain selector circuit coupled to receive an input voltage signal, which is representative of an input voltage to the power supply, to generate the duty cycle adjust signal received by the switch duty cycle controller. The duty cycle of the drive signal to be varied in response to a plurality of linear functions over a range of values of the input voltage signal.

Abstract: An embodiment of a voltage converter includes: voltage-transformer means having a primary side, designed to receive an input voltage, and a secondary side, designed to supply an output voltage; control-switch means coupled to said primary side; and a control circuit, coupled to a control terminal of said control-switch means and designed to control switching thereof as a function of a first signal correlated to said output voltage; said control circuit being provided with an error-amplifier stage, designed to process a difference between said first signal and a reference signal, wherein said error-amplifier stage is configured so as to have a transconductance characteristic with a linear-operation region, having a given slope, and at least one first clamped region, which has a slope lower than said given slope and is contiguous to said linear-operation region.

Abstract: We describe a switch mode power supply (SMPS) current regulation system comprising: a current sense signal input sensing a primary current of the SMPS; a voltage sense input to receive a voltage sense signal from a primary or auxiliary winding; a switch drive signal input to receive a drive signal; a timing signal generator coupled to said voltage sense input and to said drive signal input to generate a timing signal T0 indicating a duration of a period for which current is flowing through said primary winding and a timing signal T1 indicating a duration of a period for which current is flowing through said secondary winding; and a regulator to provide an output current regulation signal responsive to an average of the current sense signal multiplied by a ratio of T1 to T0, and wherein T0 and/or T1 are generated responsive to the voltage or current sense signal.

Abstract: A switching power source apparatus has a controller generating a drive signal that controls an ON/OFF period of a switching element 3. The controller includes a load tester for testing the switching power source apparatus when detecting an edge of the drive signal after the switching element is switched from ON to OFF, a bottom detector of the switching element during an OFF period thereof, a bottom skip state tester, and a bottom skip operation tester carrying out a pseudo resonant operation that turns on the switching element at a first minimum voltage point if the apparatus is in a heavy load state, and if the apparatus is in the light load state and if the bottom skip state has continued for a first predetermined time, shift the pseudo resonant operation to a bottom skip operation.

Abstract: An embodiment of a voltage converter, designed to convert an input voltage into a regulated output voltage, having: a voltage transformer having a primary winding receiving the input voltage, a secondary winding supplying the output voltage (Vout), and an auxiliary winding supplying a feedback signal correlated to the output voltage; a control switch, connected to the primary winding; and a control circuit, connected to a control terminal of the control switch for controlling switching thereof as a function of the feedback signal. The control circuit is provided with a sampling stage that samples the feedback signal and supplies a sampled signal. An averager stage is connected to the output of the sampling stage and implements a low-pass filtering of the sampled signal so as to reduce undesirable oscillations due to sampling.

Abstract: A control circuit includes a switch coupled to a transformer of a power converter for switching the transformer. A sampling circuit is coupled to the transformer to sample a reflected voltage of the transformer to generate a voltage signal. A switching circuit generates a switching signal to control the switch in response to the voltage signal. The minimum on time of the switching signal is changed in response to the change of an input voltage of the power converter. Because the pulse width of the reflected voltage is narrower at light load, the minimum on time of the switching signal helps the reflected voltage detection.

Abstract: A power converter according to the present invention includes a power supply unit, an output unit, and a switching controller. The power supply unit includes a primary coil of a transformer that receives an input voltage, a gate electrode, and a switch having a first electrode and a second electrode that is connected to the primary coil. The output unit includes a secondary coil of the transformer, and outputs an output voltage that is converted from the input voltage by the transformer. The switching controller includes a feedback terminal that receives a feedback voltage corresponding to the output voltage, generates a burst voltage by compensating the feedback voltage according to a maximum current value that can flow between the second electrode and the first electrode of the switch, determines whether to perform a burst mode operation according to the burst voltage, and transmits a gate signal according to performance of the burst mode operation to the gate electrode of the switch.

Abstract: A power transistor chip and an application circuit thereof have a junction field effect transistor to act as a start-up circuit of an AC/DC voltage converter. The start-up circuit can be turned off after the PWM circuit of the AC/DC voltage converter operates normally to conserve the consumption of the power. Besides, the junction field effect transistor is built in the power transistor chip. Because the junction field effect transistor is fabricated with the same manufacturing process as the power transistor, it is capable of simplifying the entire process and lowering the production cost due to no additional mask and manufacturing process.

Abstract: Voltage converters with integrated low power leaker device and associated methods are disclosed herein. In one embodiment, a voltage converter includes a switch configured to convert a first electrical signal into a second electrical signal different than the first electrical signal. The voltage converter also includes a controller operatively coupled to the switch and a leaker device electrically coupled to the controller. The controller is configured to control the on and off gates of the switch, and the leaker device is configured to deliver power to the controller. The leaker device and the switch are formed on a first semiconductor substrate, and the controller is formed on second semiconductor substrate separate from the first semiconductor substrate.

Abstract: A method and an apparatus of operating a primary-side-regulation power converter at both continuous current mode and discontinuous current mode are provided. The apparatus includes a switching circuit, a signal generator, a correlation circuit, and a feedback modulator. The signal generator generates a half signal and a second sampling pulse in response to a switching signal. The correlation circuit receives the half signal, the second sampling pulse and a switching-current signal for generating a modulating current. The feedback modulator modulates a feedback signal in response to the modulating current, a detection signal and the switching signal. The detection signal obtained from a transformer is correlated to an output voltage of the primary-side-regulation power converter. An on-period of the half signal is half of an on-period of the switching signal. The switching-current signal is sampled at a falling-edge of the half signal.

Abstract: A control circuit for use in a power converter with an unregulated dormant mode of operation is disclosed. In one aspect a power converter includes a drive signal generator that is coupled to generate a drive signal to control switching of a power switch coupled to the control circuit to regulate a flow of energy to an output of the power converter in response to an energy requirement of one or more loads coupled to the output of the power converter. A regulator circuit is coupled to charge a capacitor. The capacitor determines a time period. The regulator circuit is coupled to not charge the capacitor if the energy requirement of the one or more loads coupled to the output of the power converter falls below a threshold. The regulator is coupled to again charge the capacitor after the time period has elapsed.

Abstract: A controller for use in a power converter providing sensing of an isolated output is disclosed. An example controller includes a current controller to be coupled to an energy transfer element and an input of the power converter. A control circuit is included that generates a mode select signal coupled to be received by the current controller. A first, second or third current is enabled in the current controller in response to a selection of a first, second or third mode of operation, respectively, of the current controller by the control circuit. The first current is substantially zero, the second current is greater than the third current and the third current is greater than the first current. A first feedback circuit is coupled to the control circuit and is coupled to generate a first feedback signal representative of an output of the power converter during the first mode of operation after a period of operation of the second mode of operation of the current controller.

Abstract: In a power converter, a primary coil of a transformer receives an input voltage, and a first terminal of a switch is coupled to the primary coil. An output unit includes a secondary coil of the transformer, and outputs an output voltage to which the input voltage is converted by the transformer. A switching controller receives a feedback voltage corresponding to the output voltage and a sensing voltage corresponding to a current flowing between the first terminal and a second terminal of the switch. The switching controller determines whether to perform an operation of a burst mode based on the feedback voltage. The switching controller generates a control signal by comparing the sensing voltage with a comparison voltage during a first period of the burst mode, generates the control signal by comparing the sensing voltage with a voltage corresponding to the feedback voltage during a second period of the burst mode, and transmits the control signal to a control terminal of the switch.

Abstract: Disclosed a switching power supply apparatus which includes a voltage converting transformer including an auxiliary winding on a primary side and a switching control circuit, wherein the switching control circuit includes a detection circuit to detect a falling edge of a terminal voltage of the auxiliary winding, and controls a switching transistor connected to a primary winding of the transformer based on the terminal voltage of the auxiliary winding at the time immediately before current flowing through a secondary rectifier diode of the switching power supply apparatus becomes zero, which terminal voltage is obtained based on a detection timing of the detection circuit.

Abstract: Switch mode power converter system and method thereof. The system includes one or more isolation boxes including at least a first isolation box, an input primary winding for receiving an input signal for the switch mode power converter system, and an output secondary winding for generating an output signal for the switch mode power converter system. The switch mode power converter system is configured to convert the input signal to the output signal. One of the input primary winding and the output secondary winding is substantially enclosed in the first isolation box, and the other of the input primary winding and the output secondary winding is not enclosed in the first isolation box. The first isolation box is conductively connected to a constant-voltage source.

Abstract: 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.

Abstract: A power source constituted of: a power factor corrector controller; an electronically controlled switch responsive to the power factor corrector controller; a first inductor serially connected with the electronically controlled switch and arranged to pass a direct current there through when the electronically controlled switch is closed; a second inductor magnetically coupled to the first inductor and coupled to provide power to a load in a flyback arrangement; a third inductor magnetically coupled to the first inductor, a first end of the third inductor arranged to provide a representation of the voltage level of the direct current when the electronically controlled switch is closed, and to provide a representation of the voltage level of the power provided to the load when the electronically controlled switch is open; and an off time control circuit in communication with the power factor corrector controller and responsive to the third inductor representations.

Abstract: An example power converter includes an energy transfer element, a switch, a controller, and a current offset circuit. The controller is coupled to switch the switch between an ON state and an OFF state to regulate the output of the power converter. The controller is also adapted to terminate the ON state of the switch in response to a switch current flowing through the switch reaching a switch current threshold. An auxiliary winding of the energy transfer element is adapted to generate an auxiliary winding voltage that is representative of an input voltage of the power converter only during the ON state of the switch. The current offset circuit is coupled to the auxiliary winding to generate an offset current to flow through the switch in response to the auxiliary winding voltage, where an input current of the power converter is adjusted in response to the offset current.

Abstract: A switching-type power-supply which enables the switching with little power loss and a method of switching the switching-type power-supply are provided. The switching-type power-supply unit includes a transformer with primary, secondary, winding and control windings, a switch which switches supply of a primary current from a dotted terminal to a non-dotted terminal through the primary winding, a rectifying diode connected the secondary winding, a monitoring signal generation circuit with a diode and a resistor, the diode between GND and a dotted terminal of the control winding, the resistor between GND and a non-dotted terminal of the control winding, the monitoring signal generation circuit generating a monitoring signal at the dotted terminal of the control winding, and a control unit with a zero-point detector and a controller. The zero-point detector monitoring the monitoring signal and supplying a detection signal to the controller.

Abstract: A power converter with primary-side feedback control includes a transformer comprising a primary winding, an auxiliary winding, and a secondary winding, for transforming an input voltage into an output voltage; a transistor coupled to the primary winding for controlling electric energy transforming of the transformer according to a first control signal; a control unit coupled to the transistor for generating the first control signal according to a feedback signal in order to control the transistor to be turned on or off; and a peak detection unit coupled between the auxiliary winding and the control unit for generating the feedback signal according to a knee voltage of a first voltage signal.

Abstract: This invention provides a power supply comprising a mother board, a first socket, and a DC-DC converter module. The mother board comprises a transformer operative for transforming an input power into a first AC output power and a filter operative for receiving the first AC output power and filtering the first AC output power into a first DC output power. The first socket is mounted on the mother board and electrically coupled to a circuitry of the mother board by way of at least one conductor terminal operative for providing the first DC output power. The DC-DC converter module mounted on a printed circuit board electrically coupled to the mother board comprises a DC-DC converter operative for receiving the first DC output power and converting the first DC output power into a second DC output power and a third DC output power and a second socket operative for providing the second DC output power and the third DC output power by means of a conductive path of the printed circuit board.

Abstract: A power converter control method and apparatus is disclosed. An example power converter controller according to aspects of the present invention includes a feedback sampling circuit coupled to receive a feedback signal representative of an output of a power converter to generate feedback signal samples during enabled switching cycles. The power converter controller also includes a switch conduction control circuit coupled to the feedback sampling circuit. The switch conduction control circuit includes switch conduction enable circuitry coupled to enable or disable the conduction of a power switch during a switching cycle in response to the feedback signal samples. The switch conduction control circuit also includes switch conduction scheduling circuitry coupled to determine a varying number of future enabled and disabled switching cycles in response to the feedback signal samples from a present switching cycle and one or more past switching cycles.

Abstract: A driving circuit includes a generation unit configured to generate a driving signal for turning on and off a power switching device, the driving signal having plural levels of voltage at which the power switching device is turned on. The driving circuit also includes a switching control unit configured to switch between the plural levels of voltage at which the power switching device is turned on, depending on a status of the power switching device.

Abstract: In a RCC type switching power supply circuit, a sensing coil connected magnetically closely with an output coil is equipped in a fly-back transformer. The sensing coil is connected with a timing condenser through a Zener diode and an alternate current voltage output from the sensing coil is rectified and smoothed. Then, the difference between a detection voltage detected as a direct current voltage of the secondary side and the basic voltage of the Zener diode is supplied to the timing condenser to change the discharge/charge time and then change the timing of the switching of a first switching element in order to control the switching time of the first switching element. At the same time, applying the voltage which results from rectifying and smoothing the output voltage from the sensing coil, the charge and discharge of the timing condenser at the non-loading time is controlled in order to prolong the cycle of the switching oscillation and consequently, reduce the power loss.

Abstract: A primary side current controller for a power supply is disclosed. The primary side current controller includes a waveform detection unit, a calculation unit, and a switching controller. The waveform detection unit is used for detecting a waveform signal of the power supply and generating a captured signal. The calculation unit is coupled to the waveform detection unit and used for generating a selected voltage according to the captured signal and a feedback signal of the power supply. The switching controller is coupled to the calculation unit and used for generating a modulation signal according to the selected voltage and the feedback signal.

Abstract: A lower-cost and more precise control methodology of regulating the output voltage of a flyback converter from the primary side is provided, which works accurately in either continuous voltage mode (CCM) and discontinuous mode (DCM), and can be applied to most small, medium and high power applications such cell phone chargers, power management in desktop computers and networking equipment, and, generally, to a wide spectrum of power management applications. Two highly integrated semiconductor chips based on this control methodology are also described that require very few components to build a constant voltage flyback converter.

Abstract: An example power converter includes a clock signal generator coupled to generate a clock signal to control switching of a power switch to be coupled to the control circuit. Feedback circuitry is coupled to receive a feedback signal, which is representative of an output of a power converter during a feedback portion of an off time of the power switch. The feedback circuitry is coupled to respond to the feedback signal to control the clock signal generator to regulate a duty cycle of the feedback portion of the off time of the power switch as a proportion of a total power switch switching cycle period.

Abstract: An embodiment of a power-supply controller comprises a switching-control circuit, an error amplifier, and a signal generator. The switching-control circuit is operable to control a switch coupled to a primary winding of a transformer, and the error amplifier has a first input node operable to receive a feedback signal, a second input node operable to receive a comparison signal, and an output node operable to provide a control signal to the switching-control circuit. The signal generator is operable to generate either the feedback signal or the comparison signal in response to a compensation signal that is isolated from a secondary winding of the transformer and that is proportional to a load current through a conductor disposed between the secondary winding and a load.

Abstract: A flyback converter controller with forced primary regulation is disclosed. An example flyback converter controller includes a secondary control circuit to be coupled to a switched element coupled to a second winding of a coupled inductor of a flyback converter. The secondary control circuit is to be coupled across an output of the second winding to switch the switched element in response to a difference between an actual output value at the output of the second winding and a desired output value to force a current in a third winding of the coupled inductor that is representative of the difference between the actual output value at the output of the second winding and the desired output value. A primary control circuit is also included and is to be coupled to a primary switch coupled to a first winding of the coupled inductor. The primary control circuit is to be coupled to receive the current forced in the third winding by the secondary control circuit.

Abstract: The present invention relates to an error information detection circuit and an error feedback circuit, which detect the error of an output voltage from a voltage induced to a winding. The circuit for detecting error information of an output voltage of a transformer from voltage induced to the feedback winding of the transformer and feeding back the error information includes a flyback period detection circuit (34) for detecting a flyback period from a voltage induced to the feedback winding. A comparison unit (35) compares the induced voltage of the feedback winding with a reference voltage and outputs a result of comparison. A logic unit (36) outputs error information of an output voltage of the transformer according to a flyback period detection output of the flyback period detection circuit and the output of the comparison unit. An up/down control unit (32) outputs a feedback value corresponding to the error information.

Abstract: A hybrid constant current control system that uses both pulse width modulation (PWM) and pulse frequency modulation (PFM) control. When transitioning from constant voltage mode to constant current mode the present invention can continue to control using PWM. Thereafter, when the voltage has dropped, the present invention smoothly transitions to PFM mode. The point of transition is based upon the switching frequency and the lowest rated voltage of operation. The system and method avoids very short (narrow) Ton times which ensures accurate constant current (CC) control with bipolar junction transistor (BJT) devices. The present invention also avoids acoustic noise because the switching frequency is maintained at a high enough level to avoid such acoustic noise even when the energy transferred through the transformer is still substantial and the output voltage is not too low.