Abstract: An LED constant-current drive circuit includes a BUCK circuit consisting of a transformer T1, a diode D9, a capacitor C5 and a field effect transistor Q1; a voltage limiting circuit consisting of a resistor R1, a diode D8, a capacitor C1, a resistor R3, a triode Q2, a zener diode DZ1 and a diode D10; and a current limiting circuit consisting of a resistor R4, a triode Q3, a triode Q4 and a resistor R2. When the transistor Q1 is turned on, a current flows through a primary side of the transformer T1 and an LED load, and then flows through the transistor Q1 and the resistor R2, and then flows back to a negative electrode of a power supply. When the transistor Q1 is turned off, the current flows through the primary side of the transformer T1, the LED load and the diode D9, thus forming a loop.

Abstract: Aspects of the disclosure provide a circuit that includes a first circuit, a second circuit and a bridge circuit. The first circuit is coupled to a magnetic component to receive electric energy transferred via the magnetic component and thus configured to store the electric energy and generate a supply voltage. The second circuit is also coupled to the magnetic component. The second circuit is switchable and is configured to deplete a portion of the electric energy when the second circuit is switched on. The bridge circuit is coupled between the first circuit and the second circuit to provide a charge flow path when the second circuit is switched off.

Abstract: A system configured to provide current to power a solid-state light emitting diode in accordance with a dimming level, wherein the dimming level corresponds to an amount of light provided from the solid-state light emitting diode. The system includes a transformer and a switch. The transformer includes a coil. The transformer is configured to receive a first current. The coil is configured to, based on the first current, output a second current to power the solid-state light emitting diode. The switch is configured to, based on a dimming level that corresponds to the amount of light provided from the solid-state light emitting diode of the system, bleed a portion of the second current out of the coil to a ground reference in order to divert the portion of the second current from being supplied to the solid-state light emitting diode.

Abstract: An electrical supply device may include a transformer with a secondary winding to feed a current to a load; control circuitry for the device; an auxiliary supply source for said control circuitry. The auxiliary supply source may include an output capacitor across which a supply voltage is provided for said control circuitry; at least one charge accumulation capacitor to be traversed by the current fed to said load; a comparator sensitive to the voltage on said at least one charge accumulation capacitor; and a switch interposed between said at least one charge accumulation capacitor and said output capacitor, said switch coupled to said comparator, whereby when the voltage on said at least one charge accumulation capacitor reaches a reference level, said switch couples said at least one charge accumulation capacitor to said output capacitor by transferring onto said output capacitor the charge on said at least one charge accumulation capacitor.

Abstract: The present invention relates to a controlling circuit and controlling method for an LED driver implemented as a flyback topology. The controlling circuit may be at a primary side of a transformer of the LED driver, and include a sampling circuit, an on time sensing circuit of an output diode, a regulating signal generator, and a PWM controller. The sampling circuit may generate a sampling signal indicating output current by sampling at the primary transformer side. The on time sensing circuit can detect an on time of the output diode. The regulating signal generator can generate a regulating signal by regulating the sampling signal, a voltage reference, and the on time of the output diode. The PWM controller may generate a controlling signal to control operation of a switching device of the LED driver to maintain a substantially constant output current in accordance with the regulating signal.

Abstract: A power supply apparatus and a driving method thereof are disclosed The power supply apparatus includes: a dimmer controlling externally input power; a converter including a switch, and converting an output of the dimmer according to a duty of the switch and supplying a first current to a load; a dimming feedback unit receiving a first voltage corresponding to the first current, and having a finite gain in a DC state; and a controller controlling the duty of the switch according to an output of the dimming feedback unit. A duty of the switch is controlled according to an output of such a dimming feedback unit so that a dimming operation is performed.

Abstract: A light driving apparatus includes a first rectifying unit for receiving AC power and rectifying the AC power into DC, a switching element controlled to turn on or off by a control signal, a transforming unit having a transformer and an inductor connected to a primary side of the transformer in parallel, a second rectifying unit for rectifying a secondary side output of the transforming unit and supplying an output voltage thereof to a LED unit, and a control unit provided in the primary side to give a constant-current control function so that a secondary side output is maintained consistently. According to the present disclosure, it is possible to simplify the circuit structure of the secondary side and improve the efficiency by controlling the secondary side current at the primary side without secondary side feedback information.

Abstract: A lamp ignition system and a lamp ignition method are disclosed, where the lamp ignition system includes a converter, a transformer and a driving circuit. The converter converts an input voltage into an operating voltage for a gas discharge lamp. The transformer has a primary winding and a secondary winding, and the secondary winding is connected to the gas discharge lamp in series. The driving circuit is electrically connected to the primary winding for driving the transformer, so that the secondary winding of the transformer can output a high-frequency voltage to ignite the gas discharge lamp.

Abstract: In various embodiments, a two-switch flyback power supply may include a transformer having a primary winding and a secondary winding to feed a load; a pair of electronic switches alternatively switchable on and off to connect the primary winding of said transformer to an input line to feed said primary winding of said transformer, wherein at least one of said electronic switches is an electronic switch having a control electrode floating with respect to ground; a capacitive voltage divider arranged between said input line and the ground of the device, with the dividing point of said capacitive voltage divider connected to an intermediate point of said primary winding of said transformer; and an auxiliary secondary winding in said transformer, said auxiliary secondary winding feeding the control electrode of said at least one of said electronic switches.

Abstract: A power supply device according to one embodiment is configured to control a lighting of semiconductor light-emitting elements, wherein a dimming signal is canceled during a predetermined time period (T) from a timing immediately after power-ON, so as to light on light-emitting diodes to have a predetermined light amount, for example, a minimum light amount. After an elapse of the predetermined time period (T), cancellation of the dimming signal is released to light on the light-emitting diodes to have a light amount instructed by the dimming signal.

Abstract: A programmed start ballast circuit is presented having a mode control circuit to selectively switch an inverter output load to control operation for cathode preheating, step dimming and/or anti-arcing operation.

Abstract: A method for operating a lamp may include: Connecting a device to a pair of input connections of an electronic ballast and by this means determining a respective dimming duration for at least one predetermined situation; and Activating the lamp by the electronic ballast in at least one predetermined situation such that the lamp emits light with a reduced intensity compared with the normal intensity at which the lamp otherwise emits light over a period of a dimming duration determined for this situation.

Abstract: An illustrative LED driver circuit includes dimming control of the LED lamp. The circuit uses flyback converter topology, a power factor correction (PFC) primary side controller, a secondary side controller that includes current control and voltage control regulation, and an dimming control circuit. The dimming control circuit includes a selectable dimming control signal added together with a sensed current output signal to provide a control signal supplied to the secondary controller for output current control.

Abstract: A power supply device according to one embodiment is configured to control a lighting of semiconductor light-emitting elements, wherein a dimming signal is canceled during a predetermined time period (T) from a timing immediately after power-ON, so as to light on light-emitting diodes to have a predetermined light amount, for example, a minimum light amount. After an elapse of the predetermined time period (T), cancellation of the dimming signal is released to light on the light-emitting diodes to have a light amount instructed by the dimming signal.

Abstract: A system for driving an LED (light-emitting diode) lamp includes a dimmer circuit coupled to a line input voltage for varying a magnitude of an input voltage and a transformer having a primary winding, a secondary winding, and one or more auxiliary windings, the primary winding coupled to the dimmer circuit. The system also includes an output rectifying circuit coupled to the secondary winding for providing an output current to the LED lamp and a power switch coupled to the primary winding for controlling a current flow in the primary winding. The system further includes a controller having a comparator and a capacitor for providing a control signal to control the power switch for regulating the output current.

Abstract: There is provided an LED drive circuit that can be connected to an alternating-current power supply through a phase control dimmer and that drives an LED load, the LED drive circuit including: an LED current control circuit; a capacitance component and a resistance component that are connected in series between an input of the LED current control circuit and a reference potential; a switch element that is connected to both ends of the resistance component; and a switch control portion that turns off the switch element for a given period of time after a timing when the phase control dimmer is turned on and that turns on the switch element after the given period of time elapses.

Abstract: A controller for controlling a power converter includes a signal generator and a driver. The power converter receives an input voltage and provides an output voltage to power a load. The signal generator receives a sense signal indicating a current flowing through the power converter, receives a detection signal indicating whether the power converter operates in a predetermined state, and generates a square wave signal according to the sense signal and the detection signal. The square wave signal has a first voltage level proportional to a peak level of the current when the power converter operates in the predetermined state; otherwise, the square wave signal has a second voltage level. The driver generates a driving signal based on the square wave signal to control a current flowing through the load.

Abstract: Lighting devices comprising first, second and third strings of solid state lighting devices. One aspect further comprises means for supplying first fixed current through the first string, means for supplying second fixed current through the second string, and means for supplying current through the third string. In a second aspect, the first and second strings emit light within a specific area on a 1931 CIE Chromaticity Diagram, and the third string emits light of dominant wavelength 600-640 nm. A third aspect further comprises a power line and a power supply configured to supply a first and second fixed currents through the first and second strings, respectively, and supply a current to the third string. A method of making a lighting device, comprising measuring color output, adjusting current to first, second and/or third strings, and permanently setting currents to the first and second strings.

Abstract: Various embodiments of systems for transmitting and receiving digital and Various embodiments of systems for transmitting and receiving digital and/or analog signals across a single isolator, solid state lighting systems, or DC/DC converter feedback regulation control systems are disclosed. In one embodiment, the digital and analog signals may be modulated into a frequency modulated signal, and each pulse of the frequency modulated signal may be further encoded into a major pulse and a minor pulse. At least some of the circuits, systems and methods disclosed herein may be implemented using conventional CMOS design and manufacturing techniques and processes to provide, for example, a single integrated circuit or ASIC.

Abstract: An electronic device for a lighting system, comprising a TRIAC dimmer configured to receive a mains supply voltage and provide a phase cut voltage to the electronic device and having a control loop configured to control a duty cycle of a switched voltage converter that receives the rectified input voltage and provides drive current to a light emitting semiconductor device. The control loop has an error amplifier that is coupled to receive a sense voltage that is indicative of a current through the light emitting semiconductor device, the error amplifier is configured to provide a feedback signal to a pulse width modulation logic configured to control the duty cycle of the switched voltage converter to provide a constant drive current to the light emitting semiconductor device in response to the sense voltage, the error amplifier being coupled to receive a reference voltage that is a function of the input voltage.

Abstract: A bleeder arrangement for a phase-cut circuit for a high-impedance load and having a leading-edge phase-cut device is disclosed, the bleeder arrangement comprising: a controllable current sink adapted to sink a latching current through the leading-edge phase-cut device, and a controller for controlling the controllable current sink, wherein the controller is configured to disable the current sink after the leading-edge phase phase-cut device has latched in at least two stages. A controller for use in such an arrangement is also disclosed, as is a method of controller such a bleeder arrangement.

Abstract: A non-isolated resonant converter is provided. The provided non-isolated resonant converter includes a switch circuit, a resonant circuit and a rectifying-filtering circuit. The switch circuit, the resonant circuit and the rectifying-filtering circuit are sequentially connected. The resonant circuit includes an auto-transformer, a capacitor and an inductor, wherein the capacitor and the inductor are connected to the auto-transformer. The configuration of the provided non-isolated resonant converter has small size, low loss and high power density.

Abstract: An ignition device includes an ignition coil with a primary coil and a secondary coil, a spark plug with center and ground electrodes for discharge therebeteween, and a voltage limiting circuit. The voltage limiting circuit limits voltage applied between the electrodes of the spark plug such that the voltage has an absolute value limited within a predetermined voltage limiting value. The voltage limiting value is differentiated from each other in first and second stages. The first stage is defined as a period in which an initial discharge peak ends, the initial discharge peak being initially generated by electric energy. The second stage is defined as a period after the end of the initial discharge peak. The voltage limiting value in the first stage is lower than the voltage limiting value in the second stage.

Abstract: Enhanced active preload circuits for an LED driver implementing phase-angle dimming are disclosed. The enhanced active preload circuits may be used with any type of phase-angle control dimmer that either controls the leading edge or trailing edge of the line voltage cycle. In one example, the enhanced active preload circuitry may be used with an isolated or non-isolated LED driver converter having a Triac leading edge phase-angle control dimmer by directly sensing (e.g., by sensing the dimming level using an output/load voltage signal or output/load current signal) or indirectly sensing (e.g., by sensing a signal of output or bias winding) the Triac conduction angle. The enhanced active preload circuitry may advantageously improve performance of the LED driver by extending the dimming ratio at deep dimming and by adjusting the preload sinking current in response to a preload control signal.

Abstract: An ion generation device includes: a high voltage generation circuit; and an ion generation element. The high voltage generation circuit includes: a capacitor; a high voltage transformer; a switching element; and a pulse signal generation portion which generates a pulse signal for controlling the turning on and off of the switching element. The pulse signal generation portion adjusts a pulse width of an on-period such that the pulse width of the on-period of the pulse signal is substantially equal to a time obtained by multiplying the reciprocal of an output voltage frequency at the time of a forward operation of the high voltage transformer by one-fourth.

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 driver circuit for a dimmable solid state light source, and devices such as lamps and fixtures incorporating the same, and methods of driving such sources, are provided. A supply voltage circuit provides a supply voltage to a power factor controller circuit, such that the supply voltage is maintained within the high end of a nominal supply voltage operating range of the power factor controller circuit. The driver may also include an open circuit protection circuit for disabling the power factor controller circuit when an open circuit occurs in the load, and/or protection against electromagnetic interference (EMI).

Abstract: A fixture-compatible, dimmable illumination driving apparatus including: a rectifying unit rectifying a phase-controlled waveform of an alternating current (AC) power; a comparing unit comparing an output waveform of the rectifying unit with a first voltage according to a preset reference clock; a reference voltage generating unit generating a reference voltage corresponding to the number of high signals higher than the first voltage among outputs of the comparing unit during one cycle of the output waveform; and a pulse width modulation (PWM) signal generating unit generating a PWM signal from the reference voltage and a feedback voltage.

Abstract: A circuit for dimming a light emitting diode is provided. The circuit includes an alternating current input voltage that is delivered to a light emitting diode. The circuit also includes a correction circuit configured to monitor the input voltage, which also delivers a current to the light emitting diode, wherein the current delivered to the light emitting diode is commensurate with the input voltage. The circuit also includes a simulation circuit electrically coupled to the correction circuit and configured to deliver an additional voltage to the correction circuit to modify a setpoint voltage when the input voltage falls below a predetermined value.

Abstract: A method for dynamically controlling heat dissipation of an AC LED driving circuit has steps of connecting multiple voltage-controlled transistors and a current detection unit in series to a power loop having an LED unit, connecting a resistive element between each adjacent two of the voltage-controlled transistors to constitute multiple stages of power distribution units, detecting a voltage and a current of the power loop and calculating a consumed power value, and switching to one of the stages of power distribution units with a power range in which the current power value falls. As the higher stage of power distribution unit has more resistive elements for current to flow therethrough, it can share the power of the single-chip voltage-controlled transistor when the LED unit having higher power is used, thereby avoiding overheated condition and malfunction of the voltage-controlled transistor.

Abstract: A circuit includes a switching power converter and a load current management circuit. The switching power converter provides a first current that varies between a first current value and a second current value in response to a dimming control signal. The load current management circuit provides a second current that varies between the second current value and a third current value in response to the dimming control signal. The second current varies in accordance with the first current. For example, the second current increases as the first current decreases and the second current decreases as the first current increases. In one example, the second current value corresponds to a required minimum load current for the power converter to regulate an output voltage.

Abstract: A light emitting diode (LED) driver circuit is provided. The LED driver circuit includes an LED the LED; a power unit which provides a current to the LED through an inductor; a dimming switch which is connected to the LED and bypasses the current provided to the LED; an input unit which receives brightness information of the LED; a logic unit which calculates reference currents for each driving mode according to the received brightness information; a current control unit which controls the power unit to provide the current based on the driving mode and the calculated reference currents to the inductor; and a switch control unit which switches the dimming switch on if the driving mode of the LED driver circuit is switched to the dimming mode.

Abstract: An electric lighting driver circuit for driving an illuminating unit to emit light includes a flyback converting unit for converting a DC input voltage to a low ripple DC voltage, and a half-bridge converting unit electrically connected to the flyback converting unit, for converting the low ripple DC voltage to a low frequency, rectangular wave output voltage to drive the illuminating unit to emit light. The flyback converting unit includes a dual-output winding transformer connected to the half-bridge converting unit. The dual-output winding transformer includes a first winding at a primary side of the dual-output winding transformer and a second winding and a third winding at a secondary side of the dual-output winding transformer. The third winding converts leakage inductance attributed to the first winding and the second winding to electrical energy that is provided to the half-bridge converting unit.

Abstract: A main transformer is arranged such that a load is connected to its secondary winding side. A first error amplifier generates a feedback signal that corresponds to the difference between a detection signal which indicates the electrical state of the load and a predetermined first reference voltage. A current generating resistor is arranged between a current generating transistor and a fixed voltage terminal. A second error amplifier is arranged such that the first input terminal receives the electric potential at a node that connects the current generating transistor and the current generating resistor, a predetermined second reference voltage is input to the second input terminal thereof, and the output terminal thereof is connected to the control terminal of the current generating transistor. An adjustment resistor is arranged between the output terminal of the first error amplifier and a node that connects the current generating transistor and the current generating resistor.

Abstract: A switching power supply device includes: a chopper circuit that adjusts a DC voltage input through a reactor to a desired DC voltage by performing an on/off operation of a switching element; an inverter circuit that converts an output of the chopper circuit into a desired AC voltage; a first capacitor that is provided on a side of the inverter circuit relative to the switching element; a second capacitor that is provided on a side of the inverter circuit relative to the switching element; and a resistor that is in a resonant loop formed by three constituent elements that are the first capacitor, the second capacitor, and a wiring inductance between the chopper circuit and the inverter circuit, where the resistor is connected in series to the second capacitor and inserted between the DC bus-bars.

Abstract: A single magnetic storage element is used to provide power to multiple lighting devices, which may be strings of light-emitting diodes (LEDs) of different color. A switching circuit controls alternating application of energy among the multiple lighting devices and another switching circuit may charge the primary winding to different energy levels to control the intensity of the multiple lighting devices. In particular, the multiple lighting devices may be controlled to provide a desired color profile while dimming the lighting devices, while requiring only a single magnetic storage element for supplying energy to the lighting devices.

Abstract: Implemented are a switching power supply device and a light-emitting diode lighting device in which a variation in load current can be suppressed against a wide range of variation in AC voltage. The configuration of the switching power supply device and the light-emitting diode lighting device includes: a rectifier unit which rectifies AC input voltage and outputs pulsating-current voltage; a power converting unit which receives the pulsating-current voltage and supplies a predetermined load current to a load; a current detecting unit which detects the load current; a drive control unit which controls the power converting unit to regulate the load current to a constant level; and an input voltage detecting unit which detects a variation in the AC input voltage. The drive control unit controls the power converting unit depending on the variation in the AC input voltage detected by the input voltage detecting unit.

Abstract: A lighting device includes a lighting part, a switching part and a luminance fine-tuning part. The lighting part at least includes a first light emitting diode unit for outputting light with a first color temperature and a second light emitting diode unit for outputting light with a second color temperature. The switching part is coupled with a power source. By changing the number of times the switching part is turned on, the light with desired color temperature and luminance is produced by the lighting part according to the user's requirements. By operating the luminance fine-tuning part, the selected luminance is slightly increased or decreased.

Abstract: A resonant DC-DC converter used to drive an LED array includes a half-bridge converter configured to receive DC input power and produce a square wave voltage. A resonant tank circuit that includes an inductive element, a first resonance capacitor, and a second resonance capacitor, is coupled to the half-bridge converter to receive the square wave voltage such that a generally sinusoidal AC voltage is produced across the second resonance capacitor. An output transformer with a primary winding and one or more secondary windings, is coupled in parallel to the second resonance capacitor, and a clipping circuit is coupled to the primary winding such that the voltage across the primary winding does not substantially exceed the voltage of the DC input power. An output rectifier is coupled to the one or more secondary windings of the output transformer and is configured to produce a generally DC output voltage.

Abstract: A system for configuring at least one output parameter of a lighting load power supply, the lighting load power supply having a programmable controller for regulating the output parameter to a target value and having a memory for storing a variable for setting the target value of the output parameter, the power supply having a communication port for receiving data for setting the target value, the system comprising a computer executing software allowing a user to select a target value of an output parameter of the lighting load power supply and having a first port providing data related to the selected output parameter; and a programming device having a second port in communication with the first port of said computer and for providing data relating to said selected output parameter in a form usable by said lighting load power supply to said communication port of said lighting load power supply for programming said programmable controller to set the output parameter to the selected target value.

Abstract: An emergency lighting device (1) for operating a light source, in particular an LED, incorporates an energy storage unit (4), a charging circuit (3) to be supplied with mains supply voltage (Uin) for charging the energy storage unit (4) during a charging operation, wherein the charging circuit (3) has potential isolation, and a driver circuit (5) supplied by the energy storage unit (4) during operation of the emergency light, for operating the light source. A control unit (2) is further provided that is designed to monitor the state of the mains supply voltage (Uin) during the charging operation, and to activate emergency operation upon detecting an emergency state, wherein the control unit (2) determines the state of the mains supply voltage (Uin) from operating parameters of the emergency lighting device (1) measured on the output side of the charging circuit (3).

Abstract: A discharge lamp lighting circuit includes a DC/DC converter which generates from an input voltage a drive voltage to be applied to a discharge lamp of a driven object. A first drive voltage generating path has one end to which the input voltage is applied, and at the other end of which is an output capacitor on an output side of the DC/DC converter. A second drive voltage generating path has one end to which the input voltage is applied, and at the other end of which is the output capacitor. The second drive voltage generating path is different from the first drive voltage generating path. A control circuit controls ON/OFF of the first drive voltage generating path. The discharge lamp lighting circuit is arranged so that the voltage of the output capacitor when the first drive voltage generating path is in an ON-state becomes higher than the voltage of the output capacitor when the first drive voltage generating path is not so.

Abstract: The present invention relates to a power converter for an LED assembly, the power converter comprising—a switched mode power supply arranged to power the LED assembly, an AC/DC converter arranged to provide a DC supply voltage to the switched mode power supply, a control unit arranged to receive an input signal representing a required load voltage for powering the LED assembly, the control unit being arranged to control the AC/DC converter based on the input signal.

Abstract: The present application relates to an illumination device having a light source module, a power supply module, a driving module, a control module and a start module. The driving module outputs a driving current to the light source module based on a power supply from the power supply module. The control module controls the magnitude of the driving current based on a first voltage signal generated by the power source module. After receiving the first voltage signal, the control module controls the driving module to steadily increase the driving current in a first stage output. After receiving the first voltage signal again, the control module controls the driving module to output a constant driving current equal to the driving current at the end of the first stage.

Abstract: A driving circuit and lighting equipment using the same are provided. The driving circuit includes a first power receiving terminal, a second power receiving terminal and a power conversion unit. The first power receiving terminal receives an alternating current (AC) input signal. The second power receiving terminal is electrically coupled to a predetermined potential. The power conversion unit is electrically coupled to the first and second power receiving terminals for transforming the AC input signal into corresponding two AC output signals of different phases, wherein the two AC output signals are with the same current.

Abstract: An electronic ballast circuit includes a power factor correction circuit, a control and amplifier circuit, a ballast controller circuit and a ballast driver circuit. The ballast driver circuit includes a resonant circuit that connects to a lamp and a strike voltage limiter circuit that regulates the behavior of the resonant circuit. An overcurrent sensor circuit may be included to indirectly the control the ballast controller circuit via the control and amplifier circuit. The strike voltage limiter circuit uses varistors to change the resonant frequency of the resonant circuit to limit the voltage to the lamp.

Abstract: An LED driver for controlling the intensity of an LED light source includes a power converter circuit for generating a DC bus voltage, an LED drive circuit for receiving the bus voltage and controlling a load current through, and thus the intensity of, the LED light source, and a controller operatively coupled to the power converter circuit and the LED drive circuit. The LED drive circuit comprises a controllable-impedance circuit coupled in series with the LED light source. The controller adjusts the magnitude of the bus voltage to a target bus voltage and generates a drive signal for controlling the controllable-impedance circuit. To adjust the intensity of the LED light source, the controller controls the magnitudes of both the load current and the regulator voltage. The controller controls the magnitude of the regulator voltage by simultaneously maintaining the magnitude of the drive signal constant and adjusting the target bus voltage.

Abstract: A buck DC-to-DC converter having a novel output protection mechanism, comprising: a buck converter circuit, having a line input end, a DC output end, a first feedback end, and a second feedback end; a voltage divider, having an input terminal and an output terminal, the input terminal being coupled to the DC output end of the buck converter circuit, and the output terminal coupled to the first feedback end of the buck converter circuit for providing a first feedback voltage; and an output current sensing resistor, having one end coupled to the DC output end of the buck converter circuit, and another end coupled to the second feedback end of the buck converter circuit for providing a second feedback voltage; wherein the buck converter circuit uses the first feedback voltage and the second feedback voltage to generate a protection signal.

Abstract: A lighting fixture that suppresses blinking and flickering phenomena even when operating at very low luminance levels includes: a light source including at least one solid state light-emitting element; and a lighting driver circuit controlling the light source in accordance with a control signal. The lighting driver circuit includes an isolating flyback circuit and a control circuit. The isolating flyback circuit switches power from a DC power source and smooths the output. The control circuit controls switching operation performed by a switching element of the isolating flyback circuit via PWM signal. The control circuit provides a frequency component in accordance with the control signal to a reference signal outputted by a reference signal generator. In accordance with results of detection of the reference signal and a current flowing through the light source, the control circuit provides a stop period during which a driver controller driving the switching element is stopped.

Abstract: A control apparatus for LED diodes includes a dimmer TRIAC electrically connected in series between a power supply and a LED lighting converter. The converter comprises a transformer, with a primary winding coupled with an input terminal and a secondary winding coupled with an output terminal, and a switch coupled to the primary winding to regulate the current through the primary winding and regulate the output voltage. The apparatus comprises a control device adapted to control said switch determining the on period and the off period of the switch to maintain constant the output current to supply said LED diodes. The apparatus comprises a detector connected to the secondary winding of the transformer and adapted to detect the conduction angle of the TRIAC; the control device is adapted to regulate the output current to supply said LED diodes in response to the TRIAC conduction angle detected by the detector.