Abstract: An NMOS switch driving circuit and a power supply device are provided. The NMOS switch driving circuit includes a power-supply unit, a switch unit, a power conversion unit, and a driving unit. The power-supply unit is configured to output a first voltage. The switch unit is electrically coupled between the power-supply unit and a first interface and configured to establish or disconnect an electrical coupling between the power-supply unit and the first interface. The power conversion unit includes a port coupled to the power-supply unit and another port electrically coupled to the switch unit via the driving unit. The power conversion unit is configured to convert the first voltage into a constant driving voltage and output the driving voltage to the switch unit via the driving unit to drive the switch unit to be switched on, to establish the electrical coupling between the power-supply unit and the first interface.

Abstract: A power supply device for suppressing magnetic saturation includes a bridge rectifier, a boost inductor, a power switch element, a first PWM (Pulse Width Modulation) IC (Integrated Circuit), a first output stage circuit, an input switch circuit, a transformer, a first capacitor, a second output stage circuit, and a detection and control circuit. A leakage inductor and a magnetizing inductor are built in the transformer. The detection and control circuit includes an NTC (Negative Temperature Coefficient) resistor disposed adjacent to the transformer. The detection and control circuit detects the first voltage slope relative to the power switch element, and it detects the second voltage slope relative to the first output stage circuit. The detection and control circuit limits the inductive current flowing through the magnetizing inductor according to the first voltage slope, the second voltage slope, and the feedback voltage from the NTC resistor.

Abstract: A power converter includes an input side to receive an input voltage, and an output side to provide an output voltage, a main switch, a controller, a transformer having a primary winding that couples the main switch to the input side, an active clamp switch coupled to the input side by an active clamp capacitor, and an active clamp controller circuit. The active clamp controller circuit includes a sampling circuit to generate a sampled main switch voltage, a delay circuit to generate a delayed sampled main switch voltage, a voltage comparison circuit, and an active clamp switch controller circuit configured to i) enable the active clamp switch based on a first comparison between the sampled main switch voltage and the delayed sampled main switch voltage, and ii) disable the active clamp switch based on a second comparison between the sampled main switch voltage and the delayed sampled main switch voltage.

Abstract: A display system is disclosed. The display system includes an electronic device including first and second interfaces and a display apparatus. The electronic device is configured to: rectify external alternating current (AC) power by direct current (DC) power based on a first ground, convert the DC power into power based on a second ground, provide the converted power to the display apparatus through a first interface connected to the second ground, and provide a signal received from an external device through a second interface connected to an earth ground to the display apparatus through the first interface, wherein a ground of the display apparatus is the same as the second ground and the second ground is different from the earth ground.

Abstract: A driver circuit is disclosed.

Abstract: A comparator circuit included in a computer system employs an inverter circuit as a high-speed comparison circuit. To allow the inverter circuit to compare an input signal to a particular threshold value, a trip point of the inverter circuit is adjusted to match the threshold value by modifying a voltage level of a power supply node coupled to the inverter. To modify the voltage level of the power supply node, a replica of the inverter circuit is biased to generate a bias signal that corresponds to the trip point of the inverter circuit. A comparator circuit compares the bias signal to the threshold value, and adjusts the voltage level of the power supply node using results of the comparison. An output circuit adjusts an output of the inverter circuit to generate a full-rail output signal.

Abstract: Systems and methods for calibrating a tester that is used to calibrate conducted electrical weapons (“CEWs”). Providing a known magnitude of current for a calculated amount of time to a measurement capacitor stores a known amount of charge on the capacitor. The voltage corresponding to the known charge can be used to measure the amount of charge provided by a pulse of a stimulus signal while calibrating a CEW. A real-time clock may be used to ensure the accuracy of the time measurements over long time periods. Accurate measurement of resistors in a load circuit provides further tester accuracy.

Abstract: A multi-output dimmable CLASS-2 power supply in accord with American standard connected to a dimming control signal includes a switching mode power supply circuit, a dimming control signal to PWM signal transforming circuit, and an overcurrent protection control circuit. The overcurrent protection control circuit includes an overcurrent protection circuit, a MOS transistor, and a resistor. If the multi-output dimmable power supply is required to have n outputs, the multi-output dimmable power supply in accord with American standard CLASS-2 includes n overcurrent protection control circuits, the dimming control signal to PWM signal transforming circuit (12) includes n output ends, and the n overcurrent protection control circuits include n overcurrent protection circuits, n MOS transistors, and n resistors, and the n overcurrent protection control circuits have an identical circuit connection.

Abstract: A power converter includes an input side to receive an input voltage, and an output side to provide an output voltage, a main switch, a controller, a transformer having a primary winding that couples the main switch to the input side, an active clamp switch coupled to the input side by an active clamp capacitor, and an active clamp controller circuit. The active clamp controller circuit includes a sampling circuit to generate a sampled main switch voltage, a delay circuit to generate a delayed sampled main switch voltage, a voltage comparison circuit, and an active clamp switch control circuit configured to i) enable the active clamp switch based on a first comparison between the sampled main switch voltage and the delayed sampled main switch voltage, and ii) disable the active clamp switch based on a second comparison between the sampled main switch voltage and the delayed sampled main switch voltage.

Abstract: A power supply device includes: a power supply circuit that converts an AC voltage into a DC voltage; and a control circuit that controls the power supply circuit, wherein the power supply circuit includes: a rectifying and smoothing circuit that rectifies and smoothes the AC voltage; a first voltage converting circuit that converts the voltage and outputs a first DC voltage; a second voltage converting circuit that switches the first DC voltage by a switching circuit to output a second DC voltage; a feedback circuit that detects and feeds back an output voltage of the first voltage converting circuit; and a selection circuit that switches a reference voltage of the feedback circuit, and the control circuit sets the switching circuit to be in a continuous connection state when a normal mode is shifted to a power saving mode and gradually switches the reference voltage.

Abstract: The present subject matter relates to a method and a system for selecting a ring back tone to be provided to a caller. The method comprising selecting, by a subscriber, an editable audio file with a predetermined duration; encrypting the selected editable audio file on a storage device; communicating, by a communication interface, a start time of the selected editable audio file to the server, the server transcodes and smoothens the selected portion of the editable audio file; transferring, by the server, the transcoded audio file to the mobile operator network as a ring back tone.

Abstract: A system comprises a first energy system, a range extender, and a controller. The range extender has a second energy system, first and second converters, and a by-pass. The first converter is selectably coupled between the first energy system and an electric load, the second converter is selectably coupled between the second energy system and at least one of an output side of the first converter and an input side of the electric load, and the by-pass is selectably coupled between the first energy system and at least one of the output side of the first converter, an output side of the second converter and the input side of the electric load.

Abstract: A controller of a power converter includes a sample-and-hold unit and an adjustment unit, wherein the power converter is applied to a Universal Serial Bus power delivery adapter system. The sample-and-hold unit is used for sampling a voltage to generate a sampling voltage during each period of a gate control signal, wherein the sampling voltage corresponds to an output voltage of the power converter. The adjustment unit is coupled to the sample-and-hold unit for adjusting at least one of a frequency of the gate control signal, a current flowing through a primary side of the power converter, and a resistance of a compensation resistor of the controller according to the sampling voltage.

Abstract: A charging circuit including a transformer, a storage element, a switch element, a first resistor, and a current detection unit is provided. The transformer includes a primary coil and a secondary coil. The storage element is coupled to the secondary coil. The switch element is coupled to the primary coil. The first resistor is coupled to the primary coil. The current detection unit detects current flowing through the first resistor. When the current reaches a set current, the current detection unit sends a full signal to de-activate the switch unit.

Abstract: A converter may include a transformer, an overcurrent protection switch configured to be installed at a primary side of the transformer to prevent an overcurrent, a comparator configured to detect a voltage of the overcurrent protection switch to convert the detected voltage into an output current sensing value and compare the output current sensing value with a reference value, and a protection controller configured to normally operate or forcibly turn off the overcurrent protection switch depending on a comparison result of the comparator.

Abstract: The present invention provides a flyback power converter, a secondary side control circuit, and a control method thereof. The flyback power converter converts an input voltage to an output voltage, and provides a load current to a load circuit. The flyback power converter includes: a transformer circuit, a power switch circuit, a switch current sense circuit, a primary side control circuit, and a secondary side control circuit. The secondary side control circuit adaptively adjusts a frequency of a zero of a compensator gain function and/or a mid-frequency gain of the compensator gain function according to the load current, such that a number of poles of a system open loop gain function of the flyback power converter is at most more than a number of zeroes of the system open loop gain function by one under a crossover frequency.

Abstract: A switching power source, a method and a control chip for controlling the same are provided. The switching power source includes: a filtering and rectifying module, connected with an AC power source and configured to filter and rectify an alternating current outputted from the AC power source to obtain a direct current; a control module, connected with the filtering and rectifying module and configured to obtain an amplitude of the alternating current from the direct current, to adjust a frequency of a control signal according to the amplitude, in which the control module decreases the frequency of the control signal continuously or intermittently when the amplitude increases, and to output the control signal; and a primary constant current circuit, connected with the control module and the filtering and rectifying module respectively, and configured to receive the control signal and to output a constant current according to the control signal.

Abstract: System and method for adjusting a threshold of a power conversion system. The system includes a threshold generator configured to receive a first signal and generate a threshold signal based on at least information associated with the first signal, a comparator configured to receive the threshold signal and a second signal and generate a comparison signal, and a gate driver configured to generate a drive signal based on at least information associated with the comparison signal. The gate driver is coupled to at least a switch configured to receive the drive signal and affect a current flowing through a primary winding coupled to a secondary winding. If the second signal is larger than the threshold signal in magnitude, the drive signal causes the switch to open. The drive signal is associated with a switching frequency.

Abstract: In a power converter, a driver drives a switching element using a manipulated variable therefor to convert input power into output power. A first measuring unit measures a value of a first electric parameter depending on the input power. A first determiner determines, from the measured value of the first electric parameter, a first feedback controlled variable. A second measuring unit measures a value of a second electric parameter indicative of the output power, and a calculator calculates, based on the measured value of the second electric parameter and a command value for the second electric parameter, a second feedback controlled variable. A selector selects, based on the measured value of the first electric parameter, one of the first feedback controlled variable and the second feedback controlled variable. A second determiner determines the manipulated variable using the selected one of the first and second feedback controlled variables.

Abstract: A charging circuit for charging a battery is provided. A power supplier has a communication interface coupled to a cable for receiving command-data and generates a DC voltage and a DC current in accordance with the command-data. A controller is coupled to the battery for detecting a battery-voltage and generates the command-data in accordance with the battery-voltage. A switch is coupled to the cable for receiving the DC voltage and the DC current through a connector. The DC voltage and the DC current generated by the power supply are coupled to the cable, and the DC voltage and the DC current are programmable in accordance with the command-data. The command-data generated by the controller is coupled the cable through a communication circuit of the controller. The controller is coupled the connector for detecting a connector-voltage and control an on/off state of the switch in response to the connector-voltage.

Abstract: An effective method enhances energy saving at low load in a resonant converter with a hysteretic control scheme for implementing burst-mode at light load. The method causes a current controlled oscillator of the converter to stop oscillating when a feedback control current of the output voltage of the converter reaches a first threshold value, and introduces a nonlinearity in the functional relation between the frequency of oscillation and said feedback control current or in a derivative of the functional relation, while the control current is between a lower, second threshold value and the first threshold value, such that the frequency of oscillation remains equal or smaller than the frequency of oscillation when the control current is equal to the second threshold value. Several circuital implementations are illustrated, all of simple realization without requiring any costly microcontroller.

Abstract: The present invention relates to an LED luminaire driving circuit with high power factor, comprising: a filter unit, a rectifier unit, a transformer unit, a power switch unit, a zero current detecting unit, a feedback unit, an error amplifier unit, and a power switch driving unit. Particularly, the LED luminaire driving circuit proposed by the present invention does not include any optocoupler feedback circuits, so it is able to effectively reduce the entire circuit manufacturing cost of this LED luminaire driving circuit. Moreover, this LED luminaire driving circuit can selectively work under CCM operation or DCM operation with high power factor (PF˜1), and provide stable output voltage signal and output current signal to load end. In addition, this LED luminaire driving circuit performs excellent stability and current modulation error rate (<±3%).

Abstract: A power supply apparatus and a method of controlling the same. The power supply apparatus includes a DC/AC converting unit; a transformer; a AC/DC converting unit; and a loss compensating unit disposed before an inductor in a secondary side output stage of the transformer and compensating for power loss due to the inductor in a light load condition. The loss compensating unit is a circuit comprising a capacitor and a semiconductor switch element connected in series. The semiconductor switch element is turned off in a load condition greater than a light load and turned on in a light load condition according to a control instruction from an external control unit.

Abstract: A direct current to direct current converter includes: a transformer configured to vary a direct-current voltage applied to a first side and output the varied direct-current voltage to a second side; a switch configured to periodically switch the voltage applied to the first side of the transformer; a load-current detecting circuit configured to detect load current flowing in the second side of the transformer; and a switching-frequency switching circuit configured to switch, when a magnitude of the load current detected by the load-current detecting circuit is smaller than a predetermined threshold, a frequency for switching the switch from a first frequency to a second frequency lower than the first frequency, and to switch, when the magnitude of the load current detected by the load-current detecting circuit is larger than the predetermined threshold, the frequency for switching the switch from the second frequency to the first frequency.

Abstract: A system for sensing voltage in an isolated converter includes an input circuit isolated from an output circuit using a first transformer, the first transformer having a primary coil and a secondary coil, wherein the output circuit includes an output inductor and an output capacitor, and wherein the input circuit includes a power source that provides power to the output circuit through the first transformer; a feedback winding coupled to the output inductor to form a second transformer; and a monitor circuit that calculates a voltage across the output capacitor using a voltage across the feedback winding, a voltage across the primary coil of the first transformer, a turns ratio of the first transformer, and a turns ratio of the second transformer in order to provide feedback to control the input circuit.

Abstract: In one embodiment, an AC/DC power converter can include: a rectifier bridge and a filter capacitor for converting an external AC voltage to a half-sinusoid DC input voltage; a first storage component, where during each switching cycle in a first operation mode, a first path receives the half-sinusoid DC input voltage to store energy in the first storage component, and a first current through the first storage component increases; a second storage component, where a second path receives a second DC voltage to store energy in the second storage component, and a second current through the second storage component increases; and a third storage component, where in a second operation mode, the first current decreases to release energy from the first to the third storage component, where the second DC voltage includes a voltage across the third storage component through a third path.

Abstract: The present disclosure provides a control circuitry used in a computing system, for enabling or disabling a standby module of a power supply. The control circuitry is electrically coupled to two nodes of the standby module, and comprises a determination circuit, a transistor, and an optical coupler. The present disclosure further provides a power saving method used in a computing system is illustrated. Whether the computing system is turned off is determined. If the computing system is turned off, a setting that whether the turned off computing system requires the standby voltage is judged. If the turned off computing system does not require the standby voltage, a standby module of a power supply is disabled.

Abstract: A switching mode power supply (SMPS) includes a rectifying device configured for converting a periodically varying input AC (alternating current) voltage into a DC (direct current) voltage, and a transformer including a primary winding, a secondary winding, and an auxiliary winding. The primary winding is coupled to the rectifying device. An input capacitor is coupled to the rectifying device and the primary winding of the transformer. A first power switch is coupled to the input capacitor. A control circuit is coupled to the first power switch and is configured to control the first power switch based on a phase or amplitude of the input AC voltage. By controlling the charging and discharging of the input capacitor, power is provided to the primary winding during a longer portion of the AC input voltage cycle, allowing the rectifier device to have a larger conduction angle to increase a power factor (PF).

Abstract: The present invention relates to a circuit for driving power switch, a power supply apparatus, and a method for driving a power switch. According to an embodiment of the present invention, a circuit for driving power switch, which includes a variable oscillator for varying a frequency according to a change in primary side input voltage to output a reference signal for duty control; and a duty control unit for receiving a feedback signal fed back from a secondary side output signal and the reference signal for duty control from the variable oscillator and outputting a duty control signal for driving a power switch, is provided. Further, a power supply apparatus and a method for driving a power switch are provided.

Abstract: A dimmable LED driver adapted to be operated with a dimmer that is configured to generate a predetermined conductive angle, wherein the dimmable LED driver comprises: a rectifier configured to convert an alternating current output by the dimmer to a direct current, a buck PFC block configured to adjust an output voltage of the direct current so as to obtain a stable output voltage, a second buck DC/DC block configured to realize output of a constant current after the stable output voltage is realized, a dimming block configured to, after realizing output of the constant current, accomplish a dimming function jointly with the second buck DC/DC block, and an MCU configured to control the buck PFC block, the second buck DC/DC block and the dimming block.

Abstract: A bi-directional DC/DC converter includes at least one module having a module input for providing a bi-directional module input current, and a module output with an output inductor for providing a bi-directional module output current. A transformer has a primary winding wound around a transformer core and connected to the module input, and a secondary winding wound around the core and connected to the module output. A primary set of switches is connected in an H-bridge configuration between the module input and the primary winding. And, a secondary set of switches is connected in an H-bridge configuration between the module output and the secondary winding. A current sensing component senses the module output current. A hysteretic control drives the primary set of switches to control flux. The hysteretic control drives the secondary set of switches to control the module output current as a function of the sensed module output current.

Abstract: In a switching power supply apparatus, when it is detected at time t1 that a voltage Vis has exceeded a first threshold Vth1, a timer counting a period of time T1 is started, and the number times the input voltage Vis does not exceed Vth1 is started to be counted. When the timer expires before the count reaches a predetermined number, a first overcurrent protection operation is performed. When it is detected at time t2 that Vis has exceeded a second threshold Vth2, a second overcurrent protection operation is immediately performed. As a result, appropriate overcurrent protection is performed in accordance with the operating state of a load.

Abstract: Apparatus and methods are provided for use with power supplies. A controller regulates power supply output by way of feedback signaling. Current pulses generated by an electrical load are detected in the feedback signaling and are processed to derive a sequence of digital bits. The digital bits are subjected to validity testing and decoded as digital data. Operations of the power supply are adjusted and requests for information are answered in accordance with the digital data.

Abstract: A switching power supply device includes a switching element to which a DC input is supplied, a frequency control circuit which controls a switching frequency of the switching element, a frequency detection circuit which detects the switching frequency of the switching element, and a duty ratio control circuit which controls a switching duty ratio based on the frequency detected by the frequency detection circuit. The duty ratio control circuit controls the switching duty ratio such that the switching frequency becomes an approximately maximum frequency.

Abstract: System and method for regulating a power converter. The system includes a comparator configured to receive a first signal and a second signal and generate a comparison signal based on at least information associated with the first signal and the second signal. The first signal is associated with at least an output current of a power converter. Additionally, the system includes a pulse-width-modulation generator configured to receive at least the comparison signal and generate a modulation signal based on at least information associated with the comparison signal, and a driver component configured to receive the modulation signal and output a drive signal to a switch to adjust a primary current flowing through a primary winding of the power converter. The modulation signal is associated with a modulation frequency corresponding to a modulation period.

Abstract: Some implementations are directed to a A DC-to-DC converter that includes a power transformer having a primary side and a secondary side and a plurality of power transistors coupled to the primary side of the transformer. The converter also includes a secondary bias supply coupled to the secondary side of the transformer and a secondary side controller coupled to the secondary side of the transformer and configured to generate a feedback control signal based on a voltage level associated with the secondary side of the transformer. The the secondary side controller receives operating power only from the secondary bias supply.

Abstract: A step-up transformer includes main, auxiliary, and secondary windings. The secondary winding steps up the voltage across the main winding. A rectifier rectifies the voltage across the secondary winding into a high-voltage output. A voltage converter produces a feedback signal from the high-voltage output, the feedback signal reflecting the magnitude of the high-voltage output. An integrator receives the feedback signal and a reference signal indicative of a target high-voltage output. A DC power supply supplies drain current into a field effect transistor (FET). The auxiliary winding has one end that receives the output of the integrator and the other end that outputs an AC voltage to a differentiator. The differentiator has a resistor connected between the gate of the FET and the ground, and a parallel circuit of a resistor and a capacitor, the parallel circuit connecting between the auxiliary winding and the gate of the FET.

Abstract: A power conversion apparatus includes a switch circuit which drives switching elements based on a control signal, a feedback section which performs feedback control, a signal output section which outputs the control signal based on a controlled variable of the feedback control, an output value detecting section which detects an output value outputted from the switch circuit, and an operation determining unit which has an operation stop determination section which determines whether to stop operation of the switching elements based on a rate of change of the output value, and an operation start determination section which determines whether to start operation of the switching elements based on the controlled variable.

Abstract: In a power converter, a feedback controller feedback controls a manipulated variable based on a first electrical parameter depending on input power and a feedback controlled variable determined for output power. A dead-time determiner determines a value of the dead time as a function of a boundary condition variable depending on at least one of the input power and the output power. The boundary condition represents a reference for determining whether the power converter is operating in a continuous conduction mode or a discontinuous conduction mode. The continuous conduction mode is designed for a current to be continuously flowing through an inductor included in the power converter or a load as an inductor current. The discontinuous conduction mode is designed for the inductor current to be discontinuously flowing through the inductor.

Abstract: In a power converter, a driver drives a switching element using a manipulated variable therefor to convert input power into output power. A first measuring unit measures a value of a first electric parameter depending on the input power. A first determiner determines, from the measured value of the first electric parameter, a first feedback controlled variable. A second measuring unit measures a value of a second electric parameter indicative of the output power, and a calculator calculates, based on the measured value of the second electric parameter and a command value for the second electric parameter, a second feedback controlled variable. A selector selects, based on the measured value of the first electric parameter, one of the first feedback controlled variable and the second feedback controlled variable. A second determiner determines the manipulated variable using the selected one of the first and second feedback controlled variables.

Abstract: There is provided a single stage forward-flyback converter including a power converting unit switching input power to perform a forward power conversion operation while being switched on and perform a flyback power conversion operation while being switched off, a path providing unit clamping power formed by the forward power conversion operation of the power converting unit and power formed by the flyback power conversion operation thereof to provide power transfer paths, and a controlling unit controlling the power conversion operation of the power converting unit according to a voltage level of the input power.

Abstract: There are provided a switching-mode power supply (SMPS) and a switching control circuit thereof. The switching-mode power supply includes: a power supply circuit switching input power generated by rectifying AC power with a switching transistor to generate output power having a pre-set voltage level; and a switching control circuit having a charging and discharging unit generating a charge current to be charged in the switching transistor or a discharge current to be discharged from the switching transistor and a charging and discharging controller determining whether to charge or discharge the switching transistor according to a voltage level of the output power, wherein an amount of the charge current and an amount of the discharge current are linearly varied according to a voltage level of the input power.

Abstract: A current mirror circuit converts a positive-side supply voltage of a second power supply with respect to a reference potential into an electric current so as to supply the electric current to a current/voltage converting section. The current/voltage converting section converts the electric current from the current mirror circuit into a voltage with respect to the reference potential of a first power supply so as to supply the voltage to a feedback input terminal of a switching controller. Therefore, although the reference potential of the first power supply supplied to the switching controller is different from the reference potential of the second power supply, the electric current from the current mirror circuit is not influenced by the reference potential.

Abstract: A power source capable of supplying power to operate electronics of a system is disclosed. In one example, the power source takes advantage of an electrical potential difference between primary and secondary grounds. The power source can reduce system cost and power consumption.

Abstract: A power supply apparatus for LED is provided. The power supply apparatus for LED includes a transformer, a first output unit, and a second output unit. The transformer includes a primary winding, a secondary winding receiving a power induced from the primary winding, and a tertiary winding receiving the power induced from the primary winding. The first output unit is connected to the secondary winding of the transformer, and outputs a first power current to an LED in a first operating condition. The second output unit is connected to the tertiary winding of the transformer, and outputs a second power current to the LED in a second operating condition. When the LED is connected to the power supply apparatus for LED, the power supply apparatus allows a current equal to or less than a predetermined current to flow in the LED, thereby protecting the LED from an overcurrent.

Abstract: A DC/DC converter may include a power stage circuit, a pulse generator circuit, a flux density monitor, and power control logic. The power stage circuit includes an input, an output, and a transformer with a core. The power stage circuit may be configured to operate in a power transfer phase during which power is transferred from the input to the output and a reset phase during which flux density in the core of the transformer is reduced. The pulse generator circuit may be configured to generate pulses that regulate the output of the power stage circuit. The flux density monitor circuit may be configured to generate flux density information indicative of the flux density of the core of the transformer during both the power transfer phase and the reset phase. The power stage control logic may be configured to regulate the output of the power stage circuit based on the pulses and to prevent the core of the transformer from saturating based on the flux density information.

Abstract: The present invention relates to a switch control device, a power supply device, and a switch control method. A switch control device controls a switching operation of a power switch by using a feedback voltage of an output voltage. In detail, the switch control device generates the feedback current according to the feedback voltage and the feedback signal corresponding to the feedback voltage by using the feedback current. The switch control device compares the sensing signal corresponding to the drain current flowing to the power switch and the feedback signal, and turns off the power switch according to the comparison result. The switch control device increases the feedback gain rather than the feedback current during the gain compensation period after a predetermined gain compensation period, and the gain compensation period is longer than a soft start period in which the output voltage is gradually increased.

Abstract: The voltage at a spurious frequency is decreased while maintaining as much as possible the voltage at a resonance frequency of a piezoelectric transformer, thus controlling a wide voltage range with a comparatively low cost configuration. A high-voltage power supply apparatus includes a piezoelectric transformer that outputs a highest voltage at a predetermined resonance frequency, and a generating unit that generates a signal that oscillates at a drive frequency that drives the piezoelectric transformer, throughout a frequency range that includes the resonance frequency. Furthermore, the high-voltage power supply apparatus includes an output terminal connected to the piezoelectric transformer, and a constant-voltage element inserted in a path that couples the piezoelectric transformer and the output terminal.

Abstract: An isolated flyback converter for an LED driver includes a snubber circuit unit connected to the primary side of a transformer; and a snubber voltage detection unit which detects a snubber voltage of the snubber circuit unit and generates a reference voltage proportional to the detected snubber voltage. Further, the isolated flyback converter includes a switching unit with a source terminal and a drain terminal, and may be turned on or off in response to an arbitrary logic signal. Furthermore, the isolated flyback converter includes a control unit which compares a voltage supplied through the switching current sensing resistor with the reference voltage, and supplies a logic signal at relatively high level or relatively low level to the switching unit to control the switching unit such that a secondary-side current of the transformer is maintained relatively constant.

Abstract: A PFC converter (100) is disclosed that includes a voltage rectifier circuit (126, 127, 153) and a voltage regulator circuit (81, 90, 33, 54). The PFC converter (100) also includes an inductor (140) having a plurality of auxiliary windings (141, 142) coupled to the voltage rectifier circuit (126, 27, 153) and the voltage regulator circuit (81, 90,33, 54). One of the auxiliary windings (142) is arranged to supply a start up voltage (V1), during a start up stage, using the voltage rectifier circuit (126, 127, 153)to the voltage regulator circuit (81, 90, 33, 54). Another of the auxiliary windings (141)is arranged to supply a voltage (V1), during a steady-state stage, using the voltage rectifier circuit (126, 127, 153) to the voltage regulator circuit (81, 90, 33, 54).