Abstract: The present disclosure provides a variable energy lamp control circuit, including a power supply management circuit, an alternating current detection and high-frequency signal transmission circuit, a manual switch, a high-frequency signal receiving circuit, a delay circuit working power input control circuit, a work delay circuit, an alternating current sensing circuit, a control signal conversion circuit, and a driving circuit. The control signal conversion circuit is configured for controlling on and off of the variable energy lamp via the driving circuit according to a first control signal outputted from a first control signal output terminal of the alternating current detection and high-frequency signal transmission circuit, a second control signal outputted from an output terminal of the alternating current sensing circuit, and a third control signal outputted form a third control signal output terminal of the work delay circuit.

Abstract: The present disclosure relates to dimming circuit and method for LEDs. The dimming circuit obtains a DC voltage from an external AC power supply by using a TRIAC, an electronic transformer, and a rectifier bridge sequentially. The dimming circuit comprises a first power stage circuit, a second power stage, a first control circuit, and a second control circuit. The first power stage circuit has an input terminal configured to receive the DC voltage. The second power stage has an input terminal coupled to an output terminal of the first power stage and an output terminal coupled to an LED load. The first control circuit is configured to generate a first control signal in accordance with a first output voltage generated at the output terminal of the first power stage circuit, a first reference voltage and an upper threshold voltage to maintain an average value of the first output voltage to be consistent with the first reference voltage.

Abstract: In one embodiment of lighting devices and lighting systems, the lighting device has a connection for connecting to a primary power supply and has a secondary power supply, such as a battery. A measuring circuit is operable to measure an impedance of the primary power supply connection and to determine from the measurement if a main power supply has failed, and if so whether to power light sources using power from the secondary power supply.

Abstract: A method of driving LED chips, wherein the LED chips have different specifications, includes the steps of: A. defining a plurality of setting currents; B. connecting a LED chip; C. selecting one of the setting currents which matches a rated current of the LED chip; and D. providing power with the selected setting current to the LED chip. Whereby, the method could be applied to drive LED chips of several different specifications.

Abstract: A dimmer circuit and a lighting apparatus using the same are provided. The dimmer circuit comprises a dimmer, a rectifier, a sample-and-hold unit, an integral unit and a current holding circuit. The dimmer is coupled to an AC for modulating the AC into an alternating signal. The rectifier couples the dimmer and the AC for rectifying the alternating signal into a DC signal. The sample-and-hold unit is coupled to the rectifier for sampling the DC signal to obtain an average positive wave pulse. The integral unit is coupled to the sample-and-hold unit for integrating the average positive wave pulse to generate a DC voltage. The current holding circuit comprises a switch and a bleeder. The current holding circuit determines the on/off state of the switch according to a comparison between the DC voltage and a reference voltage, such that the DC signal passes through the bleeder or the switch.

Abstract: An apparatus, method, and system are provided for power conversion to supply power to a load such as a plurality of light emitting diodes. An exemplary apparatus comprises: a first power converter stage having a first power switch and a first inductive element; a second power converter stage having a second power switch and a second inductive element; a plurality of sensors; and a controller. The second power converter stage provides an output current to the load. The controller is adapted to use a sensed input voltage to determine a switching period, and is further adapted to turn the first and second power switches into an on-state at a frequency substantially corresponding to the switching period while maintaining a switching duty cycle within a predetermined range.

Abstract: A PFC LED driver having a flicker control mechanism, including: a bridge rectifier, used to generate a full-wave-rectified line input voltage according to an AC power; a single stage PFC constant average current converter, coupled with the bridge rectifier and used for forcing an input current to track the full-wave-rectified line input voltage and regulating an average value of an output current at a first preset value; and a current ripple reducing unit, in series with an LED module to form a load for the output current to flow through, wherein the current ripple reducing unit has a negative feedback control mechanism for forcing a peak of the output current approach an average value of the output current.

Abstract: A circuit arrangement may include: an inverter comprising first electronic and second electronic switches coupled in series between a first and second input connections to form a bridge center point; a drive apparatus for the first electronic switch and the second electronic switch; a current-measuring apparatus which is designed and arranged to measure the current through the inverter; a short-circuiting apparatus which is designed to short-circuit the output when the output voltage exceeds a first predefinable threshold value; and an evaluation apparatus which is coupled to the current-measuring apparatus and is designed to determine the mean value of the current through the inverter and, when the mean value undershoots a second predefinable threshold value, to drive the drive apparatus in such a manner that the latter influences the operation of the inverter, by driving the electronic switches in such a manner that the current in the short-circuiting apparatus is reduced.

Abstract: In at least one embodiment of the disclosure, a driving device for a discharge lamp includes an alternating current supply section and a frequency modulation section. The alternating current supply section supplies two electrodes of the discharge lamp with an alternating current. The alternating current comprises a plurality of modulation periods. The frequency modulation section modulates a frequency of the alternating current so as to provide a plurality of retentive periods within each of the modulation periods. Each retentive period has a constant frequency that is different from a frequency of its temporally adjacent retentive periods. The frequency modulation section lengthens a length of at least one of the retentive periods in the modulation period in response to a predetermined condition occurring. The frequency of at least one of the retentive periods is equal to or higher than a predetermined reference frequency.

Abstract: Disclosed are a driving system for a semiconductor light source and a semiconductor lighting device. The driving system includes a transformer, the transformer comprising a first coil (201) and a second coil (202) coupled to each other, the second coil (202) being used for receiving an input voltage; a switching means which is connected in series to the second coil (202) of the transformer and used for controlling energy-storing and energy-releasing of the second coil (202); and an outputting means which is connected in parallel to the second coil (202) of the transformer and used for supplying power to the semiconductor light source, wherein an induced signal is generated on the first coil (201) of the transformer due to a coupling effect between the first coil and the second coil (202) and is used for controlling the turn-on or turn-off of the switching means.

Abstract: A power-saving method for a lamp power-saving system is provided. The method includes the following steps. A lamp control unit is provided to control a fluorescent lamp. The lamp control unit includes a power conversion circuit and a preheat and lighting circuit. The preheat and lighting circuit, coupled to the power conversion circuit and two terminals of the fluorescent lamp, preheats and activates the fluorescent lamp, and outputs a feedback signal indicating a current passing through the fluorescent lamp. When the feedback signal indicates the fluorescent lamp is in a preheat mode, a resonant circuit of the preheat and lighting circuit is enabled to preheat the fluorescent lamp via a current path provided by a diode bridge of the preheat and lighting circuit. When the feedback signal indicates the fluorescent lamp is lighted, the current path of the preheat and lighting circuit is disconnected to stop preheating.

Abstract: A two-wire load control device (such as, a dimmer switch or an electronic switch) for controlling the power delivered from an AC power source to an electrical load includes a controllably conductive device for controlling the power to the load, a microprocessor operable to generate a control signal that is representative of whether the load should be controlled on or off, a capacitor operable to produce a supply voltage for powering the microprocessor, a power supply that charges the capacitor when the controllably conductive device is non-conductive, and a control circuit that receives the control signal from the microprocessor. The control circuit is operatively coupled to the controllably conductive device for maintaining the controllably conductive device non-conductive after the beginning of each half-cycle until the magnitude of the supply voltage exceeds a predetermined threshold.

Abstract: A high-frequency discharge ignition apparatus includes: a spark discharge path generation apparatus 101 for generating predetermined high voltage and supplying the generated predetermined high voltage to an ignition plug, thereby forming a path for spark discharge in a gap; a resonance apparatus 105 composed of an inductor 117 and a capacitor 116; a current supply apparatus 103 for supplying AC current to the path for spark discharge formed in the gap, via the resonance apparatus; a current level detection apparatus 115 for detecting the level of the AC current supplied from the current supply apparatus or a level corresponding to the level of the AC current, and outputting a value corresponding to the detected level; and a control apparatus 104 for controlling output of the AC current supplied from the current supply apparatus, in accordance with the output of the current level detection apparatus.

Abstract: A ballast circuit adapted for converting an input alternating current (AC) mains power received at input terminals to an output alternating current (AC) to supply a load, e.g. a gas discharge lamp. The output terminals of the ballast connect to the load in parallel with another ballast circuit. The ballast circuit is configured to supply the output AC current to the load in parallel with an AC current output of the other ballast circuit. A synchronization module attached at the output is adapted for synchronizing the output alternating current (AC) of the ballast circuit with the AC current output of the other ballast circuit. The synchronization module is configured to synchronize phase of the output alternating current with phase of the AC current output of the other ballast circuit.

Abstract: The present invention concerns LED drivers and is in particular directed to signal overlay for feature addition to an existing LED driver. Specifically, the invention is directed to an apparatus (200) for operating a LED driver (100), to a method of operating a LED driver, to a computer program for operating a LED driver and to a LED driver unit. The apparatus (200) is capable of overlaying an overlay signal (digital or analogue) to a control signal (164) of the LED driver (100) in dependence of external control information (256). The control signal (164) is provided to the LED driver at a control signal inlet (105). By overlaying the overlay signal, the apparatus (200) modulates the control signal (164) and provides a modulated control signal (164) to the same control signal inlet (105).

Abstract: An illumination apparatus includes: a series circuit of a thyristor and at least one load circuit connected across an AC power source; a current control circuit for adjusting an input current to be maintained at a predetermined level during a part or the whole of an ON period of the thyristor; and a short circuit for short-circuiting input ports of the load circuit to have a predetermined resistance during a part of the ON period of the thyristor and a part or the whole of an OFF period of the thyristor. The current control circuit and the short circuit are connected in parallel to the load circuit.

Abstract: A LED current-balance driving circuit having a current-balance coil set, a switching unit, and a control circuit is provided. The current-balance coil set has at least a first coil and a second coil, both of which are in connection with respective LED strings, for balancing currents flowing through the LED strings. The switching unit and a leakage inductance of current-balance coil set are utilized to facilitate the voltage conversion for driving the LED strings. A duty cycle of the switching unit is controlled by the control circuit according to the currents flowing through the LED strings.

Abstract: An LED drive circuit of the present invention carries out, by use of a DC-to-DC converter, light control of an LED. The light control is carried out, in a region where a light control level is equal to or greater than a certain light control level, by a DC light control method for adjusting a pulse height of an LED drive current. The light control is carried out, in a region where a light control level is equal to or less than the certain light control level, by a PDM light control method for adjusting an off period of oscillation of the DC-to-DC converter.

Abstract: An LED driving device has a first constant current source circuit and a voltage control circuit. The first constant current source outputs a first constant current to a first node and the first constant current flows into a first LED module disposed between a driving node and the first node; wherein, the first constant current source circuit has a first detection node for generating a first detection signal in response to the voltage level of the first node. The voltage control circuit is coupled to the first detection node, for outputting a control signal in response to the first detection signal to a voltage regulator circuit in order to control and modulate the voltage regulator circuit to output a driving voltage to the driving node.

Abstract: A load driving apparatus and a driving method thereof are provided. The load driving apparatus includes a power conversion circuit and a control chip. The power conversion circuit receives a DC input voltage, and drives an LED load in response to a gate PWM signal. The control chip is configured to: provide the gate PWM signal having a first preset duty cycle during a light operation period of a dimming operation, so that the LED load is fully turned on; and provide the gate PWM signal having a second preset duty cycle during a dark operation period of the dimming operation, so that the LED load is slightly turned on. The second preset duty cycle is far less than the first preset duty cycle. A current of the LED load during the light operation period is far more than a current of the LED load during the dark operation period.

Abstract: An LED driver may use a DIAC oscillator circuit to controls a semiconductor switch in a switching circuit. The DIAC oscillator circuit uses rectified line power and so it does not require a separate power source. An LED driver may uses a zero crossing circuit to provide low level dimming. The zero crossing circuit includes a linear circuit or a constant current circuit that keeps a TRIAC dimmer on and stable during low current levels.

Abstract: An LED drive circuit applied between an LED load and an AC power supply is provided. The circuit includes a rectifier, a power conversion module, a voltage regulator, a photo coupler and a controller. The rectifier rectifies and converts an AC voltage outputted from the AC power supply into a DC voltage. The power conversion module converts the DC voltage into a first drive voltage and a second drive voltage. The first drive voltage drives the LED load. The voltage regulator receives and processes the second drive voltage with a voltage regulating process to generate a third drive voltage not exceeding a maximum voltage rating of the controller. The photo coupler generates a feedback signal according to a signal outputted from the LED load. The controller receives the third drive voltage and generates a control signal to control the power conversion module according to the feedback signal.

Abstract: An insulated power supply device includes: an electric power conversion unit, a rectifier, a filter, a detection unit, a control circuit, and a signal transmission unit. The control circuit generates and outputs a control signal for a switching element that controls a current to be flown through a primary side of the electric power conversion unit. The signal transmission unit transmits, to the control circuit, a detection signal by the detection unit for detecting an output current or an output voltage. An output control pulse signal having control information in a duty ratio can be supplied as an outputted control signal individually to both of the control circuit and a secondary side of the electric power conversion unit. The output current or the output voltage can be thereby controlled.

Abstract: A lighting device includes a switching regulator having an inductor and a switching device, and a controller. The controller includes a peak current detector that outputs a peak detection signal when detecting that a current flowing through the switching device reaches a threshold, a zero-cross detector that outputs a zero-cross detection signal when a current discharged from the inductor reaches a predetermined lower limit value or less, a synchronization signal controller that outputs a periodic synchronization signal, and a switching controller. The switching controller turns on the switching device in synchronization with a start of an on-period of the synchronization signal and the zero-cross detection signal, and turns off the switching device in synchronization with the peak detection signal. The peak current detector reduces the threshold when an on-period of the synchronization signal finishes, and increases the threshold to an original value when an on-period of the synchronization signal starts.

Abstract: In one embodiment, an LED driving circuit can include: (i) a sense circuit configured to sense an inductor voltage, and to generate a sense voltage signal; (ii) a protection control circuit configured to activate a first protection control signal in response to a comparison of the sense voltage signal against a first reference voltage to indicate an LED device is in a first load state; (iii) the protection control circuit being configured to activate a second protection control signal in response to a comparison of the sense voltage signal against a second reference voltage to indicate the LED device is in a second load state; and (iv) a PWM control circuit configured to control a power switch according to the first protection control signal or the second protection control signal, based on the load state of the LED device.

Abstract: A power distribution system includes controller of a switching power converter to control the switching power converter and determine one or more switching power converter control parameters. In at least one embodiment, the switching power converter utilizes a transformer to transfer energy from a primary-side of the transformer to a secondary-side of the transformer. In at least one embodiment, the switching power converter control parameters includes a secondary-side conduction time delay that represents a time delay between when the primary-side ceases conducting a primary-side current and the secondary-side begins to conduct a secondary-side current. In at least one embodiment, determining and accounting for this secondary-side conduction time delay increases the prediction accuracy of the secondary-side current value and accurate delivery of energy to a load when the controller does not directly sense the secondary-side current provided to the load.

Abstract: A PFC LED driver capable of reducing flicker, including: a bridge rectifier, used to generate a full-wave-rectified line input voltage according to an AC power a single stage PFC constant average current converter, coupled with the bridge rectifier and used for forcing an input current to track the full-wave-rectified line input voltage and regulating an average value of an output current at a first preset value; and a peak current regulator, in series with an LED module to form a load for the output current to flow through, wherein the peak current regulator is used to regulate a peak of the output current at a second preset value, and the second preset value is higher than the first preset value.

Abstract: A high-frequency discharge ignition apparatus includes: a spark discharge path generation apparatus 101 for generating predetermined high voltage and supplying the generated predetermined high voltage to an ignition plug, thereby forming a path for spark discharge in a gap; a resonance apparatus 105 composed of an inductor 117 and a capacitor 116; a current supply apparatus 103 for supplying AC current to the path for spark discharge formed in the gap, via the resonance apparatus; a current level detection apparatus 115 for detecting the level of the AC current supplied from the current supply apparatus or a level corresponding to the level of the AC current, and outputting a value corresponding to the detected level; and a control apparatus 104 for controlling output of the AC current supplied from the current supply apparatus, in accordance with the output of the current level detection apparatus.

Abstract: A light emitting diode driving apparatus may include a power supplying unit receiving phase-controlled power and supplying operation power having a preset level, a driving unit receiving the operation power from the power supplying unit to drive a light emitting diode unit receiving the phase-controlled power, and a noise current limiting unit decreasing a noise current due to a parasitic capacitance component of the driving unit.

Abstract: The pixel circuit comprises a driving sub-circuit, a controlling sub-circuit and a light-emitting sub-circuit. The light-emitting sub-circuit includes a first organic light-emitting element and a second organic light-emitting element. The first and second organic light-emitting elements are coupled to the driving sub-circuit respectively. The controlling sub-circuit is coupled to the driving sub-circuit so as to control the driving sub-circuit to drive the first and second organic light-emitting elements, so that at an identical display stage, one of the first and second organic light-emitting elements emits light in a forward bias state and the other does not emit light in a backward bias state, and at an adjacent display stage, the bias states are switched.

Abstract: Disclosed are a controller and a relevant LED lighting module. A disclosed controller comprises a high-voltage power terminal and a low-voltage power terminal, a major switch circuit, an upward-connection terminal and a downward-connection terminal, and a management circuit. The major switch circuit is coupled between the high-voltage and low-voltage power terminals, and has a driving terminal for coupling to at least one LED. The management circuit is coupled to control the major switch circuit, and configured to communicate with an upstream controller via the upward-connection terminal and to communicate with a downstream controller via the downward-connection terminal. The upward-connection terminal is coupled to the downward-connection terminal of an upstream controller. The downward-connection terminal is coupled to the upward-connection terminal of a downstream controller. The management circuit is capable of operating in one of operation conditions.

Abstract: A power supply circuit (4) is responsive to an activating signal by supplying a discharge lamp (2) with an operating voltage on which a high voltage is temporality superposed. An insufficient current detecting circuit (46) detects abnormality of an output current supplied to the discharge lamp (2) from the power supply circuit (4). A CPU (52) stops the operation of the power supply circuit (4) in response to detection of abnormality by the insufficient current detecting circuit (46). An output nullification time period timer (50) nullifies the output of the insufficient current detecting circuit (46) for a predetermined time period measured from the supplying of the activating signal.

Abstract: A discharge lamp driving device includes: a discharge lamp driving unit which supplies drive power to a discharge lamp; and a control unit which controls the discharge lamp driving unit according to a waveform of the drive power. The waveform has n launching periods and a low-power mode lighting period. The n launching periods include a first launching period in which the drive power increases toward refresh power that is equal to or above drive power in a low-power mode and equal to or below rated power, and (n?1) launching periods in which the drive power is maintained at the refresh power. The control unit, in an x-th launching period, supplies the discharge lamp with a drive current having a drive frequency equal to or below a drive frequency of a drive current supplied to the discharge lamp in an (x?1)th launching period.

Abstract: An apparatus and a method for driving a fluorescent lamp are provided. The apparatus submitted by the present invention includes an LC resonator and an automatic frequency tracing circuit. The LC resonator is used for receiving and converting a square signal to generate a sinusoidal driving signal for driving the fluorescent lamp. The automatic frequency tracing circuit is used for making a frequency of the sinusoidal driving signal automatically following a resonant frequency of the LC resonator according to a feedback signal related to the sinusoidal driving signal.

Abstract: The inventive subject matter provides a circuit and a method for efficiently operating a lighting device, such as a light-emitting diode and a fluorescent lamp. In one aspect of the invention, the circuit includes an oscillator that generates a series of current pulses at a frequency that is at least 50,000 Hz and that corresponds to a resonant frequency of the circuit including the lighting device. The series of pulses is operated at a low duty cycle of no more than 15%. The lighting device has a manufacturer's specification for current consumption and power consumption for a specified luminosity. The circuit provides a current to the lighting device at no more than 1/500 of the manufacturer's specification to produce at least the specified luminosity. The lighting device also operates within the circuit at no more than 50% of the manufacturer's specification to produce the specified luminosity.

Abstract: Electronic circuits provide an error signal to control a regulated output voltage signal generated by a controllable DC-DC converter for driving one or more series connected strings of light emitting diodes.

Abstract: A method of controlling an ignition circuit to output an excitation voltage is disclosed. The ignition circuit is used to excite a discharge lamp and includes a transformer and a switch element which is connected to a primary winding of the transformer. The method of controlling the ignition circuit comprises steps of: (a) receiving a control signal which is set in accordance with a waveform characteristic of a predetermined excitation voltage to control an impedance of the switch element; (b) controlling a primary current in the primary winding or a primary voltage across the primary winding of the transformer by controlling the impedance of the switch element; and (c) generating the excitation voltage by the secondary winding of the transformer in accordance with the primary current or the primary voltage so as to excite the discharge lamp.

Abstract: An electrooptic device has a data line, a pixel circuit and a driver circuit which drives the pixel circuit. The driver circuit has a first feeder line, a level shift circuit to be electrically coupled with the data line and a driving control circuit which provides the first feeder line with a first voltage or a second voltage and controls operations of the level shift circuit and the pixel circuit. The level shift circuit has a second holding capacitor and a switch section which switches over condition of a connection between the second holding capacitor and the first feeder line.

Abstract: A replacement light tube for replacing a fluorescent light tube includes a bulb portion having a first end and a second end, a first end cap and a second end cap disposed at the first end and the second end, respectively, each configured to fit with a socket for the fluorescent light tube, a plurality of light emitting diodes disposed inside and extending between the first and second ends of the bulb portion, a pulse width modulator configured to receive power from a power source and modulate the received power to one of a first brightness level and a second brightness level, the second brightness level being different than the first brightness level and a current limiter comprising an inductive element coupled between the pulse width modulator and at least some of the plurality of light emitting diodes.

Abstract: Various apparatuses and methods for starting a thyristor are disclosed herein. For example, some embodiments provide an apparatus for controlling power to a load. The apparatus includes a thyristor, a secondary load switchably connected to an output of the thyristor, and a sensor connected to the secondary load. The sensor is adapted to connect the secondary load to the thyristor when the output of the thyristor falls below a predetermined level.

Abstract: There is provided a display device including a pixel array unit in which a plurality of pixels are arrayed in a matrix shape. A predetermined amount of light emission variation is added to a light emission state of each pixel and a cycle of the light emission state of the pixel array unit in the case of the addition is shorter than the cycle of a light emission state of the pixel array unit before the predetermined amount of light emission variation is added.

Abstract: There is provided a light emitting diode driving apparatus, including: a power supplying unit converting input power into driving power according to a control and supplying the converted driving power to a light emitting diode channel; a driving unit controlling current flowing in the light emitting diode channel according to a pulse width modulation (PWM) dimming signal from the outside; and a controlling unit comparing a reference level set by a duty of the PWM dimming signal with a detection voltage level of the light emitting diode channel and controlling a power converting operation of the power supplying unit according to the comparison result.

Abstract: The present invention discloses a light emitting device power supply circuit, a light emitting device control circuit and an identifiable light emitting device circuit therefor, and an identification method thereof. The light emitting device control circuit includes an operation signal generation circuit and an identification circuit. The operation signal generation circuit determines whether the light emitting device control circuit operates in an identified mode or amiss mode according to an enable signal. In the identified mode, the light emitting device control circuit operates a power stage circuit to supply an output current to an identifiable light emitting device circuit. In the miss mode, an output voltage is maintained at a predetermined level. The identification circuit determines whether the light emitting device control circuit switches from the miss mode to the identified mode according to whether the output voltage meets a condition.

Abstract: A circuit serving as a power source for light-emitting diode (LED) lighting applications, the circuit comprising a boost converter comprising a pair of boost field-effect transistors (FETs) and a boost inductor coupled to the pair of boost FETs, wherein an input voltage feeding the boost converter has a sinusoidal waveform, and wherein a half cycle of the input voltage is represented by a plurality of time slices, and a controller coupled to the boost converter and configured to determine a current time slice in the plurality of time slices, generate one or more output signals based at least in part on the current time slice and without a need to compute any multiplier function involving the input voltage, and control states of the boost FETs using the one or more output signals.

Abstract: A high intensity discharge lamp (HID) control circuit and method are provided in the present invention. The circuit includes a first winding and a second winding, both of which are coupled with a series-connected inductor of an HID lamp circuit; a current zero point detector for detecting an inductor current zero crossing signal in the HID lamp circuit; an inductor current signal generator for generating an inductor current signal in the circuit to indicate a current value of the HID lamp; a modulator having input terminals connected to the current zero point detector and the inductor current signal generator, respectively, and an output terminal connected to a driving circuit for the HID lamp; and the driving circuit for driving switches in the HID lamp control circuit.

Abstract: A circuit capable of receiving, in series with at least one light-emitting diode, a rectified A.C. voltage, comprising: a first gate turn-off thyristor connected to first and second terminals of the circuit; and a control circuit for turning off the first thyristor when the voltage between the first and second terminals exceeds a threshold.

Abstract: Disclosed is a light source control device including a power conversion unit and a control unit. The power conversion unit includes a transfer capacitor provided between a primary side circuit and a secondary side circuit. The primary side circuit is configured such that a first inductor stores energy when a first switching element is ON. The secondary side circuit is configured such that the second inductor limits a changing speed of the driving current. The power conversion unit is configured such that the driving current is raised when the first switching element is ON. The control unit turns OFF when the magnitude of the driving current exceeds the first threshold value, and turns ON the first switching element when the magnitude of the driving current falls below the second threshold value smaller than the first threshold value.

Abstract: In various embodiments, ballast for a discharge lamp includes input and output connections; inverter with bridge circuit with electronic switches and control device for controlling electronic switches, wherein switches are connected in series between input connections, wherein one electronic switch is coupled to first input connection and second electronic switch to second input connection, wherein a bridge midpoint is between electronic switches; including a current measuring device for measuring second electronic switch current; lamp choke series-connected between bridge midpoint and first output connection; capacitor parallel-connected with one of electronic switches; and coupling capacitor; wherein control device is coupled to current measuring device and renders an electronic switch conducting, if negative threshold value is exceeded when electronic switch is rendered nonconducting; or if negative threshold value of current through electronic switch is not exceeded after another electronic switch is rend

Abstract: For the purpose of power factor correction of an operating device for a lamp, an inductor (7) is supplied with an input voltage (Vin), a controllable switch element (13) coupled with the inductor (7) being opened or closed to optionally charge or discharge the inductor (7). A control unit (14) for controlling the switch element (13) is designed such that it determines, depending on an output voltage (Vout) of the power factor correction circuit, a switch-on time (Ton) for switching the switch element (13) on and controls the switch element (13) optionally according to at least a first operating mode and a second operating mode, the operation in the first operating mode and the operation in the second operating mode being dependent on the duration of the determined switch-on time (Ton).

Abstract: A line-frequency determining circuit for coupling to the output of a thyristor-switched dimmer that determines a line-frequency of an AC power source that supplies an input to the thyristor-controlled dimmer permits accurate control of periodic probing of the dimmer output. The probing is performed to predict zero-cross times of the AC power source that, in turn, are used to determine a dimming control value of the thyristor-switched dimmer. A minimum conductance is applied across the output of the dimmer during the probing intervals that begin at the turn-on time of the dimmer and last until enough information has been gathered to correctly predict a next zero crossing of the AC line voltage that supplies the input of the dimmer. The probing can be performed at intervals of an odd number of half-cycles of the AC line frequency so that internal dimmer timer operation is not affected by DC offset.