Abstract: A microchip for control of a switch mode power supply (SMPS), with said microchip also having the ability to measure capacitance of an electrode or sense plate structure or structures, and use of a low power, power supply structure to supply said microchip, said power supply structure distinct from the main energy path via said SMPS to a load. The microchip may control said SMPS to transition between an active state and an inactive state, with the measured capacitance used to determine a condition for state transition. In said SMPS inactive state, only the microchip draws power to operate its capacitive sensing circuitry, leading to a significant SMPS standby losses decrease compared to prior art. Further teachings by the present invention include capacitive sensing based data transfer, universal charging platforms for mobile devices, noise immunity enhancements, various lighting embodiments as well as SMPS operation improvements.

Abstract: A controller for use in a power supply includes a drive signal generator, a jitter signal generator, a compensator signal generator, and an arithmetic operator. The drive signal generator is coupled to output a drive signal in response to an input signal. The jitter signal generator is coupled to provide a jitter signal that is representative of a first percentage amount to modulate a switching period of the drive signal. The compensator signal generator is coupled to provide a compensator signal responsive to the jitter signal, where the compensator signal is representative of a second percentage amount to change a duty ratio of the drive signal. The arithmetic operator adjusts the input signal of the controller in response to the compensator signal to provide a compensated input signal, where the duty ratio of the drive signal is adjusted by the second percentage amount in response to the compensated input signal.

Abstract: A power conversion circuit system comprises a primary conversion circuit, a secondary conversion circuit, and a control circuit for controlling the primary and secondary conversion circuits. The primary conversion circuit comprises a primary full bridge circuit, which includes a bridge section composed of both a primary coil in a transformer and a primary magnetic coupling reactor in which two reactors are magnetically coupled, a first input/output port disposed between a positive bus bar and a negative bus bar of the primary full bridge circuit, and a second input/output port disposed between the negative bus bar of the primary full bridge circuit and a center tap of the primary coil in the transformer. The secondary conversion circuit has a configuration similar to that of the primary conversion circuit.

Abstract: An apparatus and method for a flyback power converter reduce the standby output voltage of the flyback power converter by switching the reference voltage provided by a shunt regulator of the flyback power converter or the ratio of voltage divider resistors of the shunt regulator, to reduce the standby power consumption by an output feedback circuit of the flyback power converter, the shunt regulator, and the voltage divider resistors, and thereby improve the power loss of the flyback power converter in standby mode.

Abstract: A sensing arrangement and method a sense winding is used to provide a voltage which represents the voltage appearing across an in-circuit magnetic component. In a flyback phase, when the component is supplying the output, that voltage represents an output voltage and in a supply phase, the supply voltage. This arrangement provides a solution to the problem of the disparity in magnitude of sense winding output during the two phases by proving a pull-up resistor arranged to apply bias to the voltage measured, the pull-up being to a first level during the supply period and to a second value during the flyback period, the first and second levels being selected such that the voltage across the sense winding is scaled differently during the supply period and the flyback period. The invention is suitable for use in a transformer based flyback power converter in which the magnitude disparity problem may be exacerbated by a turns ratio.

Abstract: A single stage power factor correction power supply consists of two transformers: a main transformer and an auxiliary transformer (forward transformer). The main transformer transfers energy from the primary circuit to secondary circuit. The auxiliary transformer is used to correct input current waveform. The advantage of this design over the two stages power supply is that the voltage across storage capacitor can be designed to be only slightly higher than the peak value of the rectified input voltage. Therefore, it uses less energy to correct input current waveform and less EMC problem because it has less current through the inductor than two stage PFC power supply.

Abstract: The embodiments herein describe a power converter including a controller that estimates input current of the power converter. The controller estimates the input current without explicitly sensing the input current. The estimated input current can be used in various applications such as regulating power factor and total harmonic distortion as well as estimating current required to maintain proper operation of a dimmer switch in light emitting diode lamp systems.

Abstract: A circuit includes a transformer configured with a primary winding and a secondary winding that are driven from a voltage supplied by a thermoelectric generator (TEG). The circuit includes a bipolar startup stage (BSS) coupled to the transformer to generate an intermediate voltage. The BSS includes a first transistor device coupled in series with the primary winding of the transformer to form an oscillator circuit with an inductance of the secondary winding when the voltage supplied by the TEG is positive. A second transistor device coupled to the secondary winding of the transformer enables the oscillator circuit to oscillate when the voltage supplied by the TEG is negative. After startup, a flyback converter stage can be enabled from the intermediate voltage to generate a boosted regulated output voltage.

Abstract: System and method are provided for protecting a power converter. The system includes a first comparator, and an off-time component. The first comparator is configured to receive a sensing signal and a first threshold signal and generate a first comparison signal based on at least information associated with the sensing signal and the first threshold signal, the power converter being associated with a switching frequency and further including a switch configured to affect the primary current. The off-time component is configured to receive the first comparison signal and generate an off-time signal based on at least information associated with the first comparison signal. The off-time component is further configured to, if the first comparison signal indicates the sensing signal to be larger than the first threshold signal in magnitude, generate the off-time signal to keep the switch to be turned off for at least a predetermined period of time.

Abstract: In one embodiment, an apparatus includes a sampling component. The sampling component receives a first voltage signal on a primary side of a transformer and monitors the first voltage signal to determine a voltage sampling time. The determined voltage sampling time is when the first voltage signal is used to estimate a second voltage level on a secondary side of the transformer. The first component further samples the first voltage signal at the voltage sampling time to determine a first voltage level. A second component outputs a control signal to control a switch to regulate the second voltage level based on the first voltage level.

Abstract: The present invention discloses a switching regulator, including: a power stage including at least one power transistor which switches according to a switch control signal to convert an input voltage to an output voltage; a pulse width modulation (PWM) signal generator generating a PWM signal according to the output voltage; an over current detection circuit comparing a current sensing signal with a reference signal to generate an over current signal indicating whether an over current is occurring; and a signal adjustment circuit adjusting the PWM signal or a clock signal to generate the switch control signal for controlling an ON time of the power transistor of the power stage.

Abstract: A circuit includes a transformer and a controller. The transformer includes a primary winding and a secondary winding, and operates in multiple switching cycles. A switching cycle includes a charging period and a discharging period. During the charging period, the transformer is powered by the input voltage and a current flowing through the primary winding increases. During the discharging period the transformer discharges to power the load and a current flowing through the secondary winding decreases. The controller includes a pin that receives a first feedback signal indicating the input voltage during the charging period and receives a second feedback signal indicating an electrical condition of the secondary winding during the discharging period. The controller generates a first control signal and a second control signal to regulate the input voltage and an output current flowing through the load, respectively.

Abstract: A control signal circuit for estimating a current output from a transformer. The control signal circuit includes a converter circuit configured to receive a signal corresponding to a current input to the transformer and output, over a half line cycle, a plurality of values corresponding to the current output from the transformer. The half line cycle corresponds to a period that the transformer is connected to an input voltage. An output current estimator is configured to accumulate the values output from the converter circuit over the half line cycle, determine an average value of the current output from the transformer over the half line cycle, and output the average value of the current output from the transformer over the half line cycle.

Abstract: A dimmable LED power supply circuit arrangement is disclosed. The circuit arrangement includes a flyback converter coupled between an input for receiving a rectified alternating line voltage and an output providing power for at least one LED device. The flyback converter includes a transformer and a semiconductor switch for switching a primary current of the transformer. A current sensing unit provides a current sense signal dependent on the primary current. A control unit controls the switching operation of the semiconductor switch dependent on the rectified alternating line voltage and the current sense signal such that the flyback converter operates in a quasi-resonant mode of operation, whereby the current sense signal is compared with a time-varying reference signal representing the rectified alternating line voltage and whereby a switch-off time of the semiconductor switch is determined dependent on the comparison.

Abstract: A flyback converter system and feedback controlling apparatus and method of operating the same are disclosed. The feedback controlling apparatus for the flyback converter system includes a primary feedback loop unit for generating a primary feedback signal, and a secondary feedback loop unit for generating a secondary feedback signal, a loop selector. In light-load conditions, the loop selector supplies the primary feedback signal to a PWM controller for feedback control, and the secondary feedback loop unit is disabled by a power monitor to save electrical energy.

Abstract: A switching power supply circuit includes a switching element that switches power fed to a primary winding of a transformer and thus induces a voltage in the secondary winding, and an oscillation circuit that oscillates to generate a pulse signal to control switching action. The oscillation circuit repeatedly performs intermittent oscillation of the pulse signal, and in each of the intermittent oscillation cycles, increases or decreases the number of pulses in the pulse signal to lengthen or shorten the oscillating portion of the pulse signal, and at the time of lengthening or shortening, the oscillation circuit respectively lengthens or shortens an oscillation-halted portion, thus varying the period of the intermittent oscillation cycles.

Abstract: A converter is suggested comprising a transformer providing a galvanic isolation between a primary side and a secondary side of the converter; at least one switching element; a converter control unit comprising a first pin for controlling the at least one switching element and a second pin for detecting a current signal in the at least one switching element during a first phase; and for detecting an output voltage signal of the secondary side of the converter and an information regarding a current in a secondary winding of the transformer during a second phase.

Abstract: A method for operating a lamp, wherein in the preheating phase a first value of the voltage drop correlated with the reciprocal of the electrical resistance of a coil of the lamp is determined across a resistor at a first instant, and a second value of the voltage drop is determined at a second instant, may include: a) determining the difference between a first and the second value; b) b1) if the difference is greater than a first threshold value: carrying out an algorithm for lamp-type recognition; b2) if the difference is not greater than the first threshold value: c1) if the difference is greater than a second threshold value: d1) if the second value is greater than a third threshold value: determining a coil short circuit; d2) if the second value is not greater than the third threshold value: operating the lamp with the current set of operating parameters.

Abstract: A controller circuit for the control of a power converter is disclosed. An example controller circuit generates a waveform that drives a switch that controls the power converter. The controller circuit includes a divider module that generates a modification factor based on a ratio of the two input signals of the module. The circuit includes a module that generates a first waveform configured for a critical conducting mode of operation of a power converter and an on-time adjuster module that modifies the first waveform based on the modification factor and generates a second waveform. The second waveform is delivered to the switch. An example modification factor is the ratio of the output voltage to the rectified input voltage of the power converter.

Abstract: A controller includes a bypass terminal, a first power circuit, a second power circuit, and a charging control circuit. The bypass terminal is to be coupled to a bypass capacitor coupled to a secondary side of an isolated power converter. The first power circuit is coupled to the bypass terminal and a first terminal to be coupled to a first node of the secondary side. The first power circuit transfers charge from the first terminal to the bypass terminal for storage on the bypass capacitor. The second power circuit is coupled to the bypass terminal and a second terminal to be coupled to a second node of the secondary side. The second power circuit transfers charge from the second terminal to the bypass terminal for storage on the bypass capacitor. The charging control circuit controls which of the first and second power circuits transfers charge to the bypass terminal.

Abstract: A controller includes a first controller terminal, a second controller terminal, a first p-channel metal-oxide-semiconductor field-effect transistor, and a second pMOS transistor. The first controller terminal is to be coupled to a bypass capacitor coupled to a secondary side of an isolated power converter. The second controller terminal to be coupled to an output node of the secondary side. The first pMOS transistor includes a first source terminal coupled to the second controller terminal, a first drain terminal, and a first body diode. The second pMOS transistor includes a second source terminal coupled to the first controller terminal, a second drain terminal coupled to the first drain terminal, and a second body diode. A cathode of the second body diode is coupled to the second source terminal. An anode of the second body diode is coupled to the second drain terminal.

Abstract: A controller for a power converter and method of operating the same. In one embodiment, the controller includes a primary peak current circuit configured to produce a reference voltage corresponding to a primary peak current through a primary winding of a transformer of a power converter, and an offset corrector configured to provide an offset voltage to compensate for delays in the power converter. The controller also includes a summer configured to provide an offset reference voltage as a function of the reference voltage and the offset voltage, and a comparator configured to produce a signal to turn off a power switch coupled to the primary winding of the transformer as a function of the offset reference voltage.

Abstract: There is provided a power converter integrated with an auxiliary converter. The power converter includes: a flyback converter converting an input power of a power supply input terminal into a standby power through a primary side circuit connected to the power supply input terminal and a secondary side circuit magnetically coupled to the primary side circuit to supply the standby power; and a main converter converting the input power of the power supply input terminal into a main power to supply the main power, and converting the input power of the power supply input terminal into the standby power through the secondary side circuit of the flyback converter to supply the standby power, whereby the efficiency of the power converter may be improved.

Abstract: A close control of electric power converters includes a diode D1 in parallel with a switch I1; a diode D2 in parallel with a switch I2; a transformer (T1). The switches (I1, I2) are controlled, cyclically repeating the following stages: at a time T0 the switch I1 is switched on; at a time T1 the switch I1 is switched off; the switch I2 is switched on before the current passing through the diode D2 reaches zero; at a time T3 the switch I2 is switched off; and at a time T4, when the diode D1 becomes conductive, the first stage is returned to. In particular, the close control of electric power converters relates to electrically isolated electric power supplies working at high frequency with high efficiency and a high level of integration.

Abstract: System and method for regulating a power converter. A system for regulating a power converter includes a controller, a first switch, and a second switch. The controller is configured to generate a first switching signal and a second switching signal. The first switch is configured to receive the first switching signal, the first switch being coupled to an auxiliary winding of the power converter further including a primary winding and a secondary winding. The second switch is configured to receive the second switching signal and coupled to the primary winding of the power converter. The controller is further configured to, change, at a first time, the second switching signal to open the second switch, maintain, from the first time to a second time, the first switching signal to keep the first switch open, and change, at the second time, the first switching signal to close the first switch.

Abstract: In one embodiment, an integrated switch mode power supply controller can include: a multiplexing pin that receives a detection voltage signal; a switch mode power supply that receives a DC input voltage, and operates in a switching cycle having first, second, and third time intervals; during the first time interval, the detection voltage signal is proportional to the DC input voltage, and a current compensation signal is generated according to the detection voltage signal to obtain a peak inductor current; during the second time interval, the detection voltage signal is proportional to an output voltage of the switch mode power supply, and a discharging duration of current through the inductor is determined based on the detection voltage signal; and during the third time interval, the detection voltage signal is proportional to a voltage across a power transistor of the switch mode power supply.

Abstract: An example power supply includes a first power converter, a second power converter, and a shared clamp reset circuit. The first power converter is adapted to convert an input to a first voltage output and includes a first diode and a first transformer having a first primary winding. The second power converter is adapted to convert the input to a second voltage output and includes a second diode and a second transformer having a second primary winding. The shared clamp reset circuit is included in the first power converter and is coupled to the cathode of the first diode. The shared clamp reset circuit also includes a clamp connection that is coupled to the cathode of the second diode. The shared clamp reset circuit is adapted to manage leakage inductance energy within the first transformer and within the second transformer.

Abstract: A single stage AC/DC converter includes a rectifier to rectify an input AC voltage and output the input AC voltage from first and second input nodes to first and second output nodes, an input capacitor connected between the first and second output nodes to store a rectified voltage and output a constant voltage, a transformer unit to transform the voltage received from the input capacitor, and transmit the voltage to a secondary side, and a power factor correction circuit to correct a power factor of a circuit. The power factor correction circuit includes a first auxiliary diode having one terminal connected with the first input node, a second auxiliary diode having one terminal connected with the second input node, and an auxiliary winding inductor connected among opposite terminals of the first and second auxiliary diodes and the first output node or the second output node.

Abstract: An active clamp circuit for a flyback power converter is provided. The active clamp circuit includes a power transistor, a capacitor, a high-side transistor driver, a charge-pump circuit, and a controller. The power transistor is coupled in series with a capacitor to develop an active-clamper. The active-damper is coupled in parallel with a primary winding of a transformer of the flyback power converter. The high-side transistor driver is coupled to drive the power transistor. The charge-pump circuit is coupled to a voltage source and the high-side transistor driver to provide a power supply to the high-side transistor driver. The controller generates a control signal coupled to control the high-side transistor driver. The control signal is generated in response to a demagnetizing time of the transformer.

Abstract: Aspects of the invention provide a switching power supply in which frequency reduction control in a light load condition both in a power factor correction converter and a DC-DC converter restrains energy loss and achieves optimum efficiency. A switching power supply can include a power factor correction converter and a DC-DC converter. The DC-DC converter can include a load condition detecting means for detecting a condition of the load, and a frequency reducing means for reducing a switching frequency in the DC-DC converter when a light load condition is detected by the load condition detecting means. The power factor correction converter can include a frequency reducing means for reducing a switching frequency in the power factor correction converter corresponding to the load condition detected by the load condition detecting means of the DC-DC converter.

Abstract: A dual switches Flyback power converter with a wide input voltage range according to the present invention comprises an input diode and an energy-storage capacitor. The input diode can prevent the reflected voltage from the power transformer of the power converter to charge the electrolytic capacitor of the power converter. The energy-storage capacitor will store the reflected voltage and the energy of the leakage inductor of the power transformer. The energy stored in the energy-storage capacitor will be recycled to the output voltage of the power converter. Further, the input diode can be replaced by an input transistor to prevent the reflected voltage from the power transformer to charge the electrolytic capacitor.

Abstract: An example controller for use in a power converter includes an oscillator that is to be coupled to a switch of the power converter to determine a switching cycle period of the switch. The controller also includes means for controlling a duty cycle of the switch to regulate an output of the power converter and for maintaining a substantially constant rate of change of the duty cycle with respect to changes in a magnitude of a feedback signal as the controller transitions between duty cycle control modes such that a control loop gain of the power converter is substantially constant during the transition.

Abstract: A control circuit adjusts the output of a power converter by controlling a power switch, in which a primary side of a transformer, the power switch and a sensing resistor are connected in series to ground. The control circuit includes a peak current emulating unit, an error amplifier, a comparator, and a control signal generator. The peak current emulating unit samples sampling voltages from the sensing resistor and obtains a real current sensing voltage and an current sensing voltage using the sampling voltages. The error amplifier receives a fixed reference voltage and a DC voltage generated from the output of the power converter, and generates an error signal. The comparator receives the real current sensing voltage and the error signal and generates a transition signal. The control signal generator receives the transition signal and generates a control signal for controlling the power switch.

Abstract: There is provided a flyback converter, including: a power supply unit supplying input power; a transformer unit including first and second transformers converting first and second primary current from the power supply unit into first and second secondary current, respectively; a main switch unit including first and second main switches respectively intermitting the first and second primary current flowing in respective primary windings of the first and second transformers; an auxiliary switch unit including first and second auxiliary switches forming respective transfer paths for dump power present before the first and second main switches are switched on; and an auxiliary inductor unit including first and second auxiliary inductors respectively adjusting the amount of current flowing in the first and second auxiliary switches during the switching operation thereof, wherein the first and second main switches perform a switching operation while having a predetermined phase difference therebetween.

Abstract: Disclosed herein are bias voltage generating circuits configured for switching power supplies, and associated control methods. In one embodiment, a bias voltage generating circuit can include: (i) a first control circuit configured to compare a drain-source voltage of a switch against a bias voltage; (ii) a capacitor, with the bias voltage across the capacitor; (iii) a second control circuit configured to control the switch, and that is enabled when the bias voltage is at least as high as an expected bias voltage; (iv) the first control circuit being configured to control the capacitor to charge when the drain-source voltage of the switch is greater than the bias voltage; and (v) the bias voltage being less than an overvoltage protection voltage when the capacitor charges, and where the overvoltage protection voltage comprises a voltage that is a predetermined amount higher than the expected bias voltage.

Abstract: An example controller includes a feedback circuit coupled to provide feedback information representative of an output of the power converter during at least a portion of an OFF time of a power switch. A sense input receives a sense signal that is representative of a reflected voltage representative of an input voltage of the power converter during at least a portion of an ON time of the power switch. A fault detector is to be coupled to detect a fault condition in response to the reflected voltage being below a fault threshold for a fault period of time. A control is coupled to the fault detector and the feedback circuit to control switching of the power switch to regulate the output of the power converter in response to the feedback information and inhibit the switching of the power switch in response to the fault detector detecting the fault condition.

Abstract: Disclosed herein is an electric generating system using a solar cell, including: a DC/DC converter that converts output voltage generated from a solar cell into DC voltage and has a converter switching device; a snubber device that has a snubber switch clamping voltage applied to the converter switching device; and a control device that detects the voltage applied to the converter switching device and controls an operation of the snubber switch according to a detected voltage level applied to the converter switching device, thereby increasing the efficiency of the electric generating system using a solar cell while reducing switching loss and conduction loss.

Abstract: In one embodiment, an AC-DC power converter can include: (i) a rectifier bridge and filter to convert an external AC voltage to a DC input voltage; (ii) a first energy storage element to store energy from the DC input voltage via a first current through a first conductive path when in a first operation mode; (iii) a second energy storage element configured to store energy from a second DC voltage via a second current through a second conductive path when in the first operation mode; (iv) a transistor configured to share the first and second conductive paths; (v) the first energy storage element releasing energy to a third energy storage element and a load through a third conductive path when in a second operation mode; and (vi) the second energy storage element releasing energy to the load through a fourth conductive path during the second operation mode.

Abstract: A switching mode power supply with improved peak current control is disclosed. A varying reference signal is adopted to limit the peak current in the energy storage component. The varying reference signal is an exponential function of a time period when a power switch is ON, wherein the power switch is coupled to the energy storage component. The varying reference signal may be generated by a circuit comprising a RC circuit and one or several voltage sources.

Abstract: A two-transistor flyback converter includes a transformer having a primary side and a secondary side, a first transistor connected between an input voltage source and a first terminal of the primary side, a second transistor connected between ground and a second terminal of the primary side, and a diode directly connected between the first terminal of the primary side and ground. The first and second transistors are operable to switch on and off simultaneously and with no current return from the primary side to the input voltage source when the input voltage source is less than a reflected voltage from the secondary side.

Abstract: An isolated power conversion apparatus includes an isolation transformer and an auto charge pump circuit. The isolation transformer has a primary side and a second side, wherein the primary side is electrically connected to a pulsed power supply, and the secondary side has a first end and a second end; the auto charge pump circuit electrically connects the isolation transformer to a loading to improve power conversion efficiency and suppress output voltage ripples.

Abstract: A controlling circuit is provided for controlling an output voltage of a main circuit of a switched-mode power supply. The controlling circuit includes components that generate a switching status selecting signal reflecting a voltage change of the main circuit, and output a reference voltage according to a voltage output status selected according to the switching status selecting signal. Other components output a pulse width modulation controlling signal according to the reference voltage and a current signal reflecting a current change of the main circuit, and output a pulse frequency modulation controlling signal with a frequency according to a frequency output status selected according to the switching status selecting signal. Yet other components output a switching controlling signal according to the controlling signals, and control a switch of the main circuit to switch-on or switch off according to the switching controlling signal to stabilize the output voltage of the main circuit.

Abstract: An example integrated circuit for use in a power supply includes a feedback terminal, a controller and a clamp. The feedback terminal is to be coupled to receive a feedback signal that is representative of a bias voltage across a bias winding of the power supply. The controller is to be coupled to control switching of a power switch included in the power supply in response to the feedback signal. The clamp is coupled to clamp the feedback terminal to a voltage for at least a time that the bias voltage is negative with respect to an input return of the power supply.

Abstract: An integrated circuit package for use in a switch mode power converter comprises an encapsulation and a lead frame. A portion of the lead frame is disposed within the encapsulation. The lead frame includes a first conductor having a first conductive loop disposed substantially within the encapsulation. The lead frame also includes a second conductor galvanically isolated from the first conductor. The second conductor includes a second conductive loop disposed substantially within the encapsulation proximate to and magnetically coupled to the first conductive loop to provide a communication link between the first and second conductors. A first control die including a first control circuit is coupled to the first conductor. A second control die including a second control circuit is coupled to the second conductor. One or more control signals are communicated between the first and second control dice through the communication link.

Abstract: An apparatus and method for output voltage calibration of a primary feedback flyback power module extract the difference between the output voltage of the power module and a target value, and according thereto, calibrate a reference voltage which is used in regulation of the output voltage, to thereby calibrate the output voltage to be the target value.

Abstract: In a power supply system, reducing influence of a noise etc., optimal electric power is supplied corresponding to power consumption of a receiving side load, and power consumption is decreased greatly. When a potential difference detector 12 detects that a power supply voltage of the receiving side load is decreased lower than a lower limit voltage threshold or increased higher than an upper limit voltage threshold, a burst interval setting unit sets up a burst signal of a pulse width corresponding to the detection result. A burst signal generator generates a burst signal based on the setup, and excites a control primary inductor. A burst signal detector generates a pulse signal in response to electromotive force of a control secondary inductor.

Abstract: In a switching control circuit, a length of a soft start period is set by a time constant of an external circuit that is connected to a soft start terminal of a switching control IC. After a voltage of the soft start terminal has reached a predetermined voltage at the termination of the soft start period, the on-pulse period of a first switching device is limited by a maximum value. When a Zener diode is connected between the soft start terminal and ground, the upper limit voltage of the soft start terminal is a Zener voltage and, hence, the maximum on-pulse period is limited by this voltage. As a result, the switching control circuit and a switching power supply apparatus, which have a soft start function and a power limiting function, are reduced in size and cost by limiting the number of terminals.

Abstract: A Low Forward Voltage Rectifier (LFVR) includes a bipolar transistor, a parallel diode, and a base current injection circuit disposed in an easy-to-employ two-terminal package. In one example, the transistor is a Reverse Bipolar Junction Transistor (RBJT), the diode is a distributed diode, and the base current injection circuit is a current transformer. Under forward bias conditions (when the voltage from the first package terminal to the second package terminal is positive), the LFVR conducts current at a rated current level with a low forward voltage drop (for example, approximately 0.1 volts). In reverse bias conditions, the LFVR blocks current flow. Using the LFVR in place of a conventional silicon diode rectifier in the secondary of a flyback converter reduces average power dissipation and increases power supply efficiency.

Abstract: In one embodiment, a power supply controller is configured to adjust a peak value of a primary current through a power switch responsively to a difference between a demagnetization time and a discharge time of the parasitic leakage inductance of a transformer.

Abstract: An electric power converting device includes a rectifier, a flyback voltage converter and a non-isolated voltage regulator. The rectifier is for converting an alternating current (AC) signal received from an AC power source into a direct current (DC) signal. The flyback voltage converter is electrically connected to the rectifier for transforming voltage of the DC signal from the rectifier to output a regulated DC signal. The non-isolated voltage regulator is electrically connected to the flyback voltage converter for reducing a voltage ripple of the regulated DC signal from the flyback voltage converter and for outputting an output voltage to a load.