Abstract: There is provided a self-excited switching power supply circuit. A cycle control capacitor is charged with a flyback voltage generated in a feedback winding of a transformer during OFF operation period in which an exciting current does not flow in a primary winding of the transformer. An OFF control capacitor the charging speed of which changes ON operation period is charged with the charging voltage of the cycle control capacitor during the ON operation period in which an exciting current flows in the primary winding. The charging voltage of the cycle control capacitor is changed with a periodic cycle Tc sufficiently longer than an oscillation cycle To to make the oscillation cycle To of continuous oscillating operation variable based on the periodic cycle Tc. As a result, the frequency of a harmonic is distributed.

Abstract: A power converter controller and methods for its operation are provided that can control a self-oscillating power converter that uses a Bipolar Junction Transistor (BJT) as a switch by manipulating the current flowing in a control winding. The controller is able to determine the optimum time to remove a short circuit applied to the control winding, as well as being able to determine the optimum time to pass current through the control winding. The controller can further draw power from the power converter using the control winding. The controller is capable of maintaining the midpoint voltage of the power converter in the case that the converter has more than one switch. The controller estimates the output power of the converter without requiring a connection to the secondary side of the converter transformer. The controller further controls entry and exit into a low-power mode in which converter oscillations are suppressed.

Abstract: In a switching power source of a flyback converter system according to the present invention, large electric power can be applied, by reducing loss of a switching element, a coil, and an output smoothing circuit, input voltage is applied to a primary coil of a transformer, and switching drive of the input voltage is carried out by a switching element, so that direct-current electric power is outputted from a secondary coil of the transformer through a rectifier circuit. The power source apparatus includes a trigger-control circuit which detects direct-current output voltage to control an “on” period, detects that current of the secondary coil becomes zero based on a voltage signal from a control coil, and turns on the switching element, and a timer circuit which is operated according to the voltage signal of the control coil, and gives an ON signal to the trigger-control circuit according to a timing signal.

Abstract: Method and apparatus for converting the output of a thermoelectric generator to voltages compatible with implantable medical devices is provided. One apparatus includes an implantable thermoelectric generator. The apparatus includes an input terminal for receiving an input voltage generated by a thermoelectric energy converter and a charging inductor connected in series with the input terminal. The apparatus also includes a switching Field Effect Transistor (FET) connected to the inductor, and a capacitor connected to the FET and the input terminal via a diode. The FET is switched with a frequency and duty cycle such that a voltage level at an output terminal is compatible with an implantable medical device. According to various embodiments, the FET is switched using a closed loop feedback system that controls the frequency and duty cycle based on an observed voltage level at the output terminal. Other aspects and embodiments are provided herein.

Abstract: A PWM signal for driving power transistors of a half-bridge of a converter is generated with the aid of a digital circuit, in which an internal reference value is compared to the counter content of a counting ramp. In this context, a logic state of the PWM signal depends upon whether the internal reference value is greater than the counter content of the counting ramp. After each comparison between the internal reference value and the counter content, an n-bit long data word dependent on the result of this comparison is output serially as PWM signal, n being greater than or equal to 2. The resolution of the PWM signal is thereby improved by the factor n in comparison to conventional systems, without markedly increasing the circuit expenditure.

Abstract: The power supply apparatus for obtaining a direct current from an alternating voltage source includes a first DC/DC converter for outputting a first direct current and a second DC/DC converter for a second direct current lower than the first direct current from the first DC/DC converter, and the output voltage of the first DC/DC converter is changed to a lower direct current and the second DC/DC converter is driven in a continuously-conducting state.

Abstract: The present invention relates to a method for charging accumulation means via an external electrical network via at least a first (A) and a second (B) switching arm respectively comprising two switches (12), said method comprising a step for controlling the switches (12) of the switching arms (A, B) by transmission of pulse width modulation control signals, characterized in that the switches (12) of the second switching arm (B) are controlled by adapting the pulse width of the control signals so as to generate an alternating voltage (Vx) in phase opposition relative to the voltage at the terminals of a compensation inductance (7?) connected on the one hand to the second arm (B) and on the other hand to the neutral (N) of said network, so that the voltage (VN) between the neutral (N) of said network and ground is a direct voltage. The invention also relates to a charging device for implementing such a charging method.

Abstract: Consistent with an example embodiment, a circuit comprises a power factor correction stage having a DC input, a ground input, a DC output and a ground output. The circuit further includes a capacitor; a diode; and a discharge circuit. A first terminal of the diode is connected to an input of the power factor correction stage, a second terminal of the diode is connected to the first plate of the capacitor; and the second plate of the capacitor is connected to the other input of the PFC stage. The discharge circuit is connected to the capacitor and is configured to discharge the capacitor such that it contributes to the output of the PFC stage when the level of a signal at the input of the PFC stage falls below a threshold value.

Abstract: There is provided a self-excited switching power supply circuit which shifts to continuous oscillating operation immediately after the self-excited switching power supply circuit is connected to an AC power supply and started and which does not cause start-up failure while using a start-up resistor of a high resistance value to maintain standby power consumption at a low level. A bypass charging circuit connected in series to a start-up resistor is connected between a high-voltage side terminal of a DC input power supply and the gate of an oscillation field effect transistor. A charging current flowing in the start-up resistor, and additionally, a charging current to charge a start-up capacitor through the bypass charging circuit flow in a transitional period during which the voltage of the DC input power supply increases.

Abstract: A power converter controller and methods for its operation are provided that can control a self-oscillating power converter that uses a Bipolar Junction Transistor (BJT) as a switch by manipulating the current flowing in a control winding. The controller is able to determine the optimum time to remove a short circuit applied to the control winding, as well as being able to determine the optimum time to pass current through the control winding. The controller can further draw power from the power converter using the control winding. The controller is capable of maintaining the midpoint voltage of the power converter in the case that the converter has more than one switch. The controller estimates the output power of the converter without requiring a connection to the secondary side of the converter transformer. The controller further controls entry and exit into a low-power mode in which converter oscillations are suppressed.

Abstract: A circuit for boosting the voltage from a very low level voltage source to a higher level voltage output utilizing self-oscillation.

Abstract: In an induction motor group control system, magnetic energy recovery switches (3) are connected in series to an induction motor (2) directly driven by a commercial power supply, and a plurality of induction motor control devices (10) enabling voltage control and reactive power control of the induction motor 2 are employed to control generation of reactive power so as to maximize a power factor of the entire plurality of AC loads including the induction motor or compensate variations in voltage of an AC power supply (1).

Abstract: There is provided a self-excited switching power supply circuit which shifts to continuous oscillating operation immediately after the self-excited switching power supply circuit is connected to an AC power supply and started and which does not cause start-up failure while using a start-up resistor of a high resistance value to maintain standby power consumption at a low level. A bypass charging circuit connected in series to a start-up resistor is connected between a high-voltage side terminal of a DC input power supply and the gate of an oscillation field effect transistor. A charging current flowing in the start-up resistor, and additionally, a charging current to charge a start-up capacitor through the bypass charging circuit flow in a transitional period during which the voltage of the DC input power supply increases.

Abstract: A technique for controlling a power supply with power supply control element with a tap element. An example power supply control element includes a power transistor that has first and second main terminals, a control terminal and a tap terminal. A control circuit is coupled to the control terminal. The tap terminal and the second main terminal of the power transistor are to control switching of the power transistor. The tap terminal is coupled to provide a signal to the control circuit substantially proportional to a voltage between the first and second main terminals when the voltage is less than a pinch off voltage. The tap terminal is coupled to provide a substantially constant voltage that is less than the voltage between the first and second main terminals to the control circuit when the voltage between the first and second main terminals is greater than the pinch-off voltage.

Abstract: A data diode system enables one-way data flow from an unsecured device to a secured device is disclosed. The data diode system includes at least one data diode that convert a communication received from an unsecured device to a secured communication for transmission to the secured device. The data diode system includes a voltage converter that receives a negative voltage from a serial data port connection of the secured device. The voltage converter converts the negative voltage into a positive voltage in order to power the data diode.

Abstract: An output voltage monitoring circuit monitors an output voltage of a capacitor charging circuit. A first sample-and-hold circuit samples and holds a voltage of a connection point of a primary coil of a transformer and a switching transistor. A first monitoring comparator compares output of the first sample-and-hold circuit with a predetermined first reference voltage. When the output of the first sample-and-hold circuit exceeds the first reference voltage, a signal processor executes predetermined signal processing. The first sample-and-hold circuit starts a sampling period after a predetermined first time has elapsed after the switching transistor is turned OFF. When a voltage drop across a detection resistor reaches a third reference voltage, the first sample-and-hold circuit ends the sampling period.

Abstract: A voltage supply device for a load, in particular for a network, has an energy store that can be connected to connection terminals and a voltage transformer with at least one electronic switch. A reverse polarity protection is in contact with the connection terminals and is designed to convert voltage delivered from the energy store into control voltage for active activation of the electronic switch when the polarity of the voltage is reversed.

Abstract: A technique for controlling a power supply with power supply control element with a tap element. An example power supply control element includes a power transistor that has first and second main terminals, a control terminal and a tap terminal. A control circuit is coupled to the control terminal. The tap terminal and the second main terminal of the power transistor are to control switching of the power transistor. The tap terminal is coupled to provide a signal to the control circuit substantially proportional to a voltage between the first and second main terminals when the voltage is less than a pinch off voltage. The tap terminal is coupled to provide a substantially constant voltage that is less than the voltage between the first and second main terminals to the control circuit when the voltage between the first and second main terminals is greater than the pinch-off voltage.

Abstract: A light source apparatus and a light source adjusting module are provided. The light source apparatus includes a power supply, a phase modulator, an electrical transformer, a light source adjusting module and a light-emitting device. The power supply provides a first AC voltage signal. The phase modulator receives the first AC voltage signal and adjusts a conducting phase of the first AC voltage signal to generate a modulated AC voltage signal. The electrical transformer transforms the modulated AC voltage signal to generate a second AC voltage signal. The light adjusting module generates a luminance adjusting signal according to a state of the second AC voltage signal. The light-emitting device receives the luminance adjusting signal to generate a corresponding light source.

Abstract: A method and system for regulating electrical power from a non-perpetual power source. In one implementation, the method includes receiving a variable power output from the non-perpetual power source, wherein a power amplitude of the variable power output substantially varies over time; and generating a regulated current output or a regulated voltage output based in part on the variable power output received from the non-perpetual power source.

Abstract: The device (10) comprises an energy-storage transformer (14) having magnetically coupled primary and secondary windings (P and L1, L2, L3); a primary circuit (20) connecting the power supply source to a ground (M), and comprising the primary winding (P) and a static main switch (22) connected in series; a secondary winding (S1, S2, S3) designed to be connected to a load, and including the secondary winding (L1, L2, L3); and voltage control means (34) for controlling the static main switch (22) and comprising a first static control switch (36) connecting a control terminal (22A) of the static main switch (22) to ground (M).

Abstract: To provide a hybrid fuel cell system for improving converter efficiency. In a hybrid fuel cell system (1) in which a fuel cell (22) and an electricity storage device (21) are connected via a voltage converter (20), the voltage converter (20) has a plurality of phases (P1, P2, P3), and the number of phases of operation can be changed in accordance with the power passing through the voltage converter (20). As the number of phases can be changed in accordance with the power passing through the voltage converter (20), it is possible to select the number of phases that give a higher efficiency voltage conversion in accordance with the passing power, and the efficiency of the voltage converter (20) can be greatly improved.

Abstract: An isolating self-oscillation flyback converter includes a coupling transformer T1, a FET TR1, a transistor TR2, a photoelectric coupling isolator OC1 and a load feedback circuit Adj. The common polarity terminal of a feedback winding Nfb of the coupling transformer T1 is connected to the gate of the FET TR1 via a capacitance C1 and a resistance R2, and connected to the base of the transistor TR2 via a capacitance C2. The base of the transistor TR2 is also connected to the emitter of the photoelectric coupling isolator OC1. The photoelectric coupling isolator OC1 is connected to the positive terminal of the output voltage. The opposite polarity terminal of the feedback winding Nfb is connected to the collector of the photoelectric coupling isolator OC1 via a resistance R5, and connected to ground via a capacitance C5. The common polarity terminal of the feedback winding Nfb is also connected to the cathode of a diode D, and the anode of the diode D is connected to ground.

Abstract: A switching power supply includes an active device for pulling out a part of a control signal from a control terminal of the switching device in an RCC, and a control signal generation circuit that applies adjustment voltage as ON/OFF time control voltage to a control terminal of the active device. The active device pulls out the control signal so as to decrease or increase an OFF time of the switching device while fixing the ON time of the switching device when the adjustment voltage is decreased or increased in the active region of the active device, respectively. An element of a timing circuit in the RCC pulls out the control signal so as to increase or decrease an ON time of the switching device while fixing the OFF time of the switching device when the adjustment voltage is decreased or increased in the cut-off region of the active device, respectively.

Abstract: The present invention can include an image forming apparatus having an electrical load, a supplying circuit configured to supply an electrical power to the electrical load, and an output circuit configured to output a voltage according to a current value of the electrical power being supplied to the electrical load. The present invention may also provide for a controller configured to control an electrical current flowing in the electrical load based on an output voltage value of the output circuit as a feedback value, and an inhibiting circuit configured to inhibit a reverse current to flow in the output circuit when the supplying circuit is turned off.

Abstract: Circuits and methods for battery charging are disclosed. In one embodiment, the battery charging circuit comprises an AC to DC converter, a charging control switch, and a charger controller. The AC to DC converter provides a charging power to a battery pack. The charging control switch is coupled between the AC to DC converter and the battery pack. The charging control switch transfers the charging power to the battery pack. The charger controller detects a battery status of the battery pack and controls the charging control switch to charge the battery pack in a continuous charging mode or a pulse charging mode according to the battery status. The charger controller also controls the AC to DC converter to regulate the charging power according to the battery status.

Abstract: In a switching power supply device, a first switch element, which defines a main switch element of a DC-DC converter, and a third switch element, which defines a switch element of a power-factor correcting circuit, are controlled such that turn-on timings are synchronized while on-period control is independently performed to thereby prevent an increase in switching frequency and prevent noise by eliminating intermittent oscillation. Thus, it is possible to prevent intermittent oscillation control due to an increase in switching frequency of the first switch element under a light load state or a no load state. This eliminates problems of the frequency of intermittent oscillation that falls within an audible frequency range causing noise and increasing ripple voltage.

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 the power loss of the flyback power converter in standby mode.

Abstract: A power supply topology with pulse width modulation frequency control allows the use of an inductor with higher inductance in a converter. By controlling the switching frequency of the pulse width modulation signal, the inductor can achieve high efficiency during a light load condition and is also suitable for a heavy load condition.

Abstract: An exemplary DC to DC converter includes a first transistor, a second transistor, a transformer, and a pulse generating circuit having a first capacitor, a sampling resistor, a zener diode, and a first diode. A DC voltage input terminal is configured for receiving a first DC voltage and is grounded via the primary winding of the transformer, a collector electrode and an emitter electrode of the first transistor in series. A terminal of the auxiliary winding of the transformer is grounded via the inverted first diode, the non-inverted zener diode, the sampling resistor, and the first capacitor. The other terminal of the auxiliary winding is grounded. A first transistor having a base electrode connected to the DC voltage input terminal. A second transistor includes an emitter electrode a cathode of the zener diode, a collector electrode connected to a base electrode of the first transistor, and a grounded base electrode.

Abstract: A PWM controller with output current limitation makes the over-current limitations almost the same even though the input voltages are different. The designer does not need to use high specification components or add an output current limiting circuit against the over-current condition. Costs are reduced and the layout is simplified. The switch power supply includes a transformer, a power switch, a first detecting circuit for generating a first detecting signal, a second detecting circuit for generating a second detecting signal, and a controller. The transformer converts the power and outputs the power to the secondary side. The power switch has a first terminal, a second terminal, and a controlled terminal. The controller has a control terminal, a first detecting terminal for receiving the first detecting signal, and a second detecting terminal for receiving the second detecting signal. The controller performs a protecting operation according to the received signals.

Abstract: A power supply module to power the control circuit of a switching mode power supply is provided. Based on the determination of whether the switching mode power supply is under a light or open load condition, the power supply module can dynamically provide the power to the control circuit of the switching mode power supply. Therefore, the performance of the power supply can be increased and the power loss can be decreased when the switching mode power supply is under a light or open load.

Abstract: The present invention relates to voltage transformers, comprising multi-layer structures of piezoelectric ceramics, so-called piezoelectric transformers. The present invention further relates to switched mode power supplies, comprising such a piezoelectric transformer as part of a piezoelectric converter. The piezoelectric transformer according to the invention comprises a primary-side electrode arrangement (102) that can be connected to the primary-side voltage, a secondary-side electrode arrangement (104) on which the secondary-side voltage can be tapped, and an auxiliary electrode arrangement (106) for creating an auxiliary electrode voltage proportional to the secondary-side voltage, wherein the auxiliary electrode arrangement (106) is formed by at least two plane electrodes located opposite one another.

Abstract: To reduce power loss during standby. In a switching power supply device using a first power supply circuit (11) having a small output and a second power supply circuit (12) having a large output, the first power supply circuit (11) is continuously kept in an operating state and the second power supply circuit (12) is started by using an electric power generated in the first power supply circuit (11).

Abstract: A light emitting diode (LED) lighting system includes a PFC and output voltage controller and a LED lighting power system. The controller advantageously operates from an auxiliary voltage less than a link voltage generated by the LED lighting power system. The common reference voltage allows all the components of lighting system to work together. A power factor correction switch and an LED drive current switch are coupled to the common reference node and have control node-to-common node, absolute voltage that allows the controller to control the conductivity of the switches. The LED lighting system can utilize feed forward control to concurrently modify power demand by the LED lighting power system and power demand of one or more LEDs. The LED lighting system can utilize a common current sense device to provide a common feedback signal to the controller representing current in at least two of the LEDs.

Abstract: An isolating self-oscillation flyback converter includes a coupling transformer T1, a FET TR1, a transistor TR2, a photoelectric coupling isolator OC1 and a load feedback circuit Adj. The common polarity terminal of a feedback winding Nfb of the coupling transformer T1 is connected to the gate of the FET TR1 via a capacitance C1 and a resistance R2, and connected to the base of the transistor TR2 via a capacitance C2. The base of the transistor TR2 is also connected to the emitter of the photoelectric coupling isolator OC1. The photoelectric coupling isolator OC1 is connected to the positive terminal of the output voltage. The opposite polarity terminal of the feedback winding Nfb is connected to the collector of the photoelectric coupling isolator OC1 via a resistance R5, and connected to ground via a capacitance C5. The common polarity terminal of the feedback winding Nfb is also connected to the cathode of a diode D, and the anode of the diode D is connected to ground.

Abstract: Techniques are disclosed to detect a fault in the feedback circuit of a switching power supply while the power supply operates in a mode where the output is below its regulated value. The power supply delivers maximum power at a given switching frequency without a feedback signal while the output is below its regulated value. A fault protection circuit substantially reduces the average output power if there is no feedback signal for the duration of a fault time. When there is no feedback signal, the power supply increases the maximum output power by increasing the switching frequency before the end of the fault time to increase the output to a regulated value. The presence of a feedback signal when the output reaches a regulated value restores the original switching frequency and returns the output to its unregulated value. The absence of a feedback signal at the end of the fault time engages the fault protection circuit to substantially reduce the output power.

Abstract: An inventive isolated converter which exempts the auxiliary isolation devices with accurate voltage regulation is disclosed. The converter includes the primary side circuit with a primary controller controlling the on and off of the primary switch and a secondary side circuit with a secondary controller controlling the on and off of the secondary synchronous rectifier. The isolated converter uses the secondary controller to turn on the secondary synchronous rectifier after the secondary current decreases to zero to generate a negative tail current and turns off the secondary synchronous rectifier at a reference tail current peak value to generate a reflected negative current at the primary side circuit for turning on the primary switch.

Abstract: A self-oscillating switching regulator includes a control winding N3allowing a voltage to be induced therein by a magnetic flux created in a primary winding N1 of a high frequency transformer T, a capacitor C3 charged by the voltage induced in the control winding N3, a transistor Q2 that is turned off when the voltage across the capacitor C3 reaches a predetermined level, a switching element Q1 driven by the transistor Q2 to switch on or off an input current through the primary winding N1 of the high frequency transformer T, and a control winding adjuster for changing by switching the number of turns of the control winding N3 on the basis of the operating temperature.

Abstract: A switching power supply includes an active device for pulling out a part of a control signal from a control terminal of the switching device in an RCC, and a control signal generation circuit that applies adjustment voltage as ON/OFF time control voltage to a control terminal of the active device. The active device pulls out the control signal so as to decrease or increase an OFF time of the switching device while fixing the ON time of the switching device when the adjustment voltage is decreased or increased in the active region of the active device, respectively. An element of a timing circuit in the RCC pulls out the control signal so as to increase or decrease an ON time of the switching device while fixing the OFF time of the switching device when the adjustment voltage is decreased or increased in the cut-off region of the active device, respectively.

Abstract: A photocoupler for feeding back output voltage information on a secondary side of a switching power supply circuit through a light signal to control a switching operation on a primary side comprises: a light-emitting element for emitting a light signal flashing based on the output voltage information of the switching power supply circuit; a light-receiving control integrated circuit composed by integrating a light-receiving element composed of a photodiode for receiving the light signal, an amplifier circuit for amplifying an output signal of the light-receiving element, and a switching control circuit for controlling the switching operation of the switching power supply circuit, in one chip, wherein the light-emitting element and the light-receiving control integrated circuit are sealed in one package so that the light signal can be transmitted from the light-emitting element to the light-receiving element.

Abstract: A flyback system power source apparatus, which applies a voltage intermittently to a primary winding of a transformer to perform voltage outputting onto a secondary winding side of the transformer, comprises: the transformer; a synchronously rectifying element for rectifying a current in a secondary winding of the transformer; and a synchronous rectification control circuit for detecting a voltage vibration caused in a terminal voltage of the secondary winding to perform operation control of the synchronously rectifying element on the basis of the detection.

Abstract: A flyback converter has a controller to switch a power switch so as to convert an input voltage to an output voltage for a load by monitoring an output voltage dependent signal and a current sensing signal derived from a current flowing through the power switch, a light-load efficiency improving apparatus monitors the load and a supply voltage provided for the controller to selectively clamp the output voltage dependent signal when the load is lower than a first threshold value and the supply voltage is lower than a second threshold value, so as to increase the supply voltage.

Abstract: An apparatus and method are provided for suppressing the input current inrush for a voltage converter in a pre-charge stage. The voltage converter comprises a power input for receiving an input current, a power output for supplying an output voltage for a load, and an output capacitor connected to the power output. In a pre-charge stage, a current limiting device is connected between the power input and the output capacitor to limit the input current to flow therethrough, and a variable current limiting control circuit provides a control signal to the current limiting device to determine a variable maximum value for the input current.

Abstract: A voltage detection device that is connected to a DC circuit to which a DC voltage is applied and that detects the DC voltage applied to the DC circuit comprises a voltage conversion means for outputting a first voltage that increases as the DC voltage increases and a second voltage that decreases as the DC voltage increases, an error detection means for detecting an error for the first voltage and the second voltage based upon the first voltage and the second voltage when the DC voltage is 0, and a voltage calculation means for correcting a difference between the first voltage and the second voltage outputted by the voltage conversion means based upon the error detected by the error detection means and calculating the DC voltage based upon the corrected difference between the first voltage and the second voltage.

Abstract: Techniques are disclosed to detect a fault in the feedback circuit of a switching power supply while the power supply operates in a mode where the output is below its regulated value. The power supply delivers maximum power at a given switching frequency without a feedback signal while the output is below its regulated value. A fault protection circuit substantially reduces the average output power if there is no feedback signal for the duration of a fault time. When there is no feedback signal, the power supply increases the maximum output power by increasing the switching frequency before the end of the fault time to increase the output to a regulated value. The presence of a feedback signal when the output reaches a regulated value restores the original switching frequency and returns the output to its unregulated value. The absence of a feedback signal at the end of the fault time engages the fault protection circuit to substantially reduce the output power.

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 voltage detector circuitry extracts a signal on primary side of a transformer in a flyback converter, which is proportional to the output voltage of the converter without voltage drop on the rectifier diode and leakage inductance effect on the transformer, and good output regulation is achieved without opto-coupler. To accurately detect the output voltage on the primary side, the knee point of the voltage on an auxiliary winding of the transformer is detected. A current limit proportional to the input voltage of the converter is produced from the voltage on an auxiliary winding for stabilizing the output current in constant current mode.

Abstract: A high-voltage generator includes a high-voltage transformer having a primary coil, a secondary coil, and an auxiliary coil, and a PNP bipolar junction transistor. Based on the self-oscillation theory of a LC oscillator, an oscillating voltage is generated across the primary coil. The oscillating voltage is amplified to a high-level AC voltage through the secondary coil. One end of the auxiliary coil and an emitter of the transistor are coupled to an input DC voltage, and the other end of the auxiliary coil is connected to the base of the transistor through a RC circuit. One end of the primary coil is connected to the collector of the transistor, and the other end of the primary coil is connected to ground.

Abstract: A switching power supply circuit of the present invention includes: a transformer including a main winding and an auxiliary winding, which are magnetically coupled together on a primary winding side; a switching element for intermittently supplying a direct-current voltage to the main winding; and a controller for turning ON/OFF the switching element using a voltage induced across the auxiliary winding by the intermittent supply of the direct-current voltage. The switching power supply circuit includes a startup circuit, the startup circuit including: a startup switch connected to the main winding; and a driving pulse generator for outputting a driving pulse to the startup switch for turning ON the startup switch.