Abstract: An induction heating device includes the following elements: a resonance circuit; a power factor improvement circuit for boosting rectified output, supplying the output to an inverter, and improving the power factor of a commercial alternating current; and a load material detector for detecting the material of the load. The inverter includes switching elements forming a full-bridge circuit. The drive frequency of the switching elements is switched between a frequency substantially equal to a resonance frequency of the resonance circuit and a frequency substantially 1/n time (n being an integer equal to or larger than two) thereof, according to a detection result of the load material.

Abstract: An uninterruptible power supply configured to automatically detect a load level and automatically power off and disable power supply or automatically power on and enable the power supply based on a detected load level, so that energy of a backup source of the uninterruptible power supply is not wasted and a life-cycle of the uninterruptible power supply is extended.

Abstract: A control circuit of a switching regulator, which controls rectified power within a predetermined range, detects an input voltage and an input current to generate a voltage detection signal and a current detection signal respectively, and the voltage detection signal and the current detection signal are multiplied by one the other to generate a power index. The control circuit generates an error signal according to the power index and a reference signal. A low-pass-filter filters a high frequency band in the process. A control signal generation circuit of the control circuit generates a control signal according to the error signal. And a driver circuit of the control circuit generates an operation signal according to the control signal, for switching a power switch to convert the rectified power to an output voltage.

Abstract: A controller for use in a power converter includes a sensor coupled to receive a signal from a single terminal of the controller. The signal from the single terminal represents an output voltage of the power converter during at least a portion of an off time of a power switch and a line input voltage during a portion of an on time of the power switch. A switching control is to be coupled to switch the power switch to regulate the output of the power converter in response to the sensor. A power limiter is coupled to the sensor to output a power limit signal to the switching control in response to the line input voltage of the power converter. The switching control is further coupled to switch the power switch to regulate the output of the power converter in response to the power limit signal.

Abstract: Electronic devices require correct power in order to operate correctly. Receiving an incorrect power signal could potentially result in immediate and/or long term harm to the electronic device and/or catastrophic conditions. Certain devices, such as programmable logic controller (“PLC”) modules, may provide variable power to electronic devices, such as field devices comprising sensors and/or actuators. The present inventors have recognized that deciphering between AC and DC input signals before coupling electronic devices to such power sources may advantageously avoid harmful and/or catastrophic conditions. Aspects of the present invention provide an electronic circuit for deciphering between an AC and a DC input signal. Systems and methods are also described.

Abstract: A power conversion apparatus includes a MOSFET having a channel and a body diode connected in parallel. The channel of the MOSFET becomes conductive according to a control signal, so that a flow path of a regenerative current of an inductor is formed, and the body diode of the MOSFET causes the regenerative current of the inductor to flow in a forward direction. The power conversion apparatus also includes a shunt resistor and a voltage measuring unit which measure an amount of a current flowing into the MOSFET. In addition, the power conversion apparatus includes a threshold designating unit which designates a threshold current amount, and a synchronous rectification prohibiting circuit which prohibits supplying the control signal when the amount of the current measured by the shunt resistor and the voltage measuring unit is greater than the threshold current amount designated by the threshold designating unit.

Abstract: A power converter constituted of: a control circuitry; an electronically controlled switch responsive to the control circuitry; a power transformer exhibiting a primary winding and a secondary winding; a sense transformer comprising a primary current sense winding, an error current sense winding and a feedback winding, the primary current sense winding of the sense transformer and the primary winding of the power transformer coupled in series with the electronically controlled switch; a transconductance error amplifier coupled to an output of the secondary winding of the power transformer, the transconductance amplifier arranged to drive a current through the error current sense winding of the sense transformer whose value reflects an electrical characteristic of the output of the secondary winding of the power transformer, wherein the feedback winding of the sense transformer is coupled to a feedback input of the control circuitry.

Abstract: An improved valley-mode switching (VMS) scheme and circuitry for implementing the improved VMS switching scheme in a switch-mode power converter are disclosed. For a given switching cycle, a desired switch turn-on time is determined based on a pulse width modulation, pulse frequency modulation, or other suitable power converter control scheme. Also, one or more times corresponding to local minimums (valleys) are predicted for the voltage across a power switch of the switching power converter. The power switch is turned on at a valley immediately subsequent or otherwise subsequent to the desired switch time determined according to the power converter control scheme. Thus, the improved VMS scheme enables low-voltage switch operation to reduce switching loss and EMI noise without restricting the control scheme of the power converter.

Abstract: Systems and methods for controlling an electrical power supply are provided. One system includes an input configured for receiving voltage measurement signals for the power supply and a controller for one or more electrical phases of the power supply. The controller includes an integrator configured to integrate the received voltage measurement signals and to generate integrated control signals or integrated error signals. The controller is configured to generate an output signal using the integrated control signals or the integrated error signals. The system also includes an output configured to output the output signal to control switching of the power supply.

Abstract: The present invention provides a DC to AC converter including a device enabling separation of electric current into a positive portion of the circuit and a negative portion of the circuit, each portion of the circuit including an electronic switch, wherein one portion of the circuit is adapted to produce a wave form in a positive half cycle, the second portion of the circuit is adapted to produce a wave form in a negative half cycle, the voltage of the output current is fed to a polarity switch as feedback to change the polarity, and wherein the carrier duty cycle is adapted to change from 0 to 100 percent in each polarity.

Abstract: A power supply device includes: a magnetic-coupling-type multi-phase converter having first and second chopper circuits that respectively adjust respective currents flowing in first and second reactors magnetically coupled to each other, and performing voltage conversion between a DC power supply and a load; and a control circuit. The control circuit includes a determination unit and a current control unit. The determination unit determines whether the temperature of the power supply is lower than a reference temperature. In the case where the power supply temperature is lower than the reference temperature, the current control unit uses a value determined by adding an offset amount to a detected value of the reactor current to set a duty command value for the first chopper circuit and uses a detected value of the reactor current to set a duty command value for the second chopper circuit.

Abstract: A controller of a power converter is provided. The controller includes a feedback circuit, an output circuit, and a clamping circuit. The feedback circuit generates a feedback signal in accordance with output of the power converter. The output circuit generates a switching signal in accordance with the feedback signal for regulating the output of the power converter. The clamping circuit limits the feedback signal under a first level for a first load condition and limits the feedback signal under a second level for a second load condition. The clamping circuit includes a timer circuit. The timer circuit determines a slew rate of the feedback signal for increasing the feedback signal from the first level to the second level, and the second level is higher than the first level.

Abstract: A system for automatically regulating voltage on a distribution-level AC bus having an actual voltage and a nominal voltage includes an electronic power converter connected to the distribution-level AC bus. The system generates a feedback signal representative of the actual voltage of the distribution-level AC bus and produces an input control signal in response to the feedback signal. The input control signal is representative of a commanded level of reactive power. The electronic power converter is responsive to the input control signal to deliver a commanded reactive power output to the distribution-level AC bus, and the commanded reactive power output pushes the actual voltage towards the nominal voltage.

Abstract: A system for testing the existing protection schemes of a power converter. The system simulates the voltage regulator producing a voltage level below an under-voltage threshold. The system simulates the voltage regulator producing a voltage level above an over-voltage threshold. The system simulates a short in the power converter pulling down the input bus. The system simulates a short in the power converter pulling down the output bus. The system measures the system responses to these simulations against responses of a properly operating system and determines if the power converter's protection schemes are operating correctly.

Abstract: The present invention relates to a switch driving circuit and a driving method thereof that are capable of preventing hard switching. The present invention includes: a dead time controller generating an high-side switching driver controlling signal and a low-side switching driver controlling signal controlling the switching operation of the high-side switch and the low-side switch according to a dead time controlling signal; and a phase detector detecting a phase of a resonance current flowing into the second power voltage terminal to generate a phase information signal, wherein one of the high-side switch driver controlling signal and a signal corresponding thereto, and the phase information signal are compared, and if the turn-on time of the high-side switch is later than the phase change of the resonance current, the dead time is controlled for the turn-on time of the high-side switch to advance the phase change of the resonance current.

Abstract: A switching converter and method for controlling a switching converter in a quasi resonant mode of operation, wherein a sense voltage is predefined for a PWM controller to determine a switch off time of a switching element, a switch-on time of the switching element also falls in a valley of an oscillating voltage that is being applied to the switched-off switching element, and where the sense voltage is reduced in each valley occurring after a switch-off operation such that a stable operating point is thus reached under any load.

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

Abstract: A power-supply unit including a transformer, a full bridge circuit having four arm switches on a primary side of the transformer, a rectifier and smoothing circuit including two synchronous rectifier switches on a secondary side of the transformer, a choke coil, and a capacitor, an output terminal in the rectifier and smoothing circuit, a control circuit controlling ON/OFF of the four arm switches of the full bridge circuit and the two synchronous rectifier switches of the rectifier and smoothing circuit, a resonant inductor including a leakage inductor component and a parasitic inductor component on the primary side of the transformer, and a resonant capacitor, and in which the control circuit includes a timing variable unit which varies switching timings of the two synchronous rectifier switches of the rectifier and smoothing circuit based on an output current flowing in the output terminal provided in the rectifier and smoothing circuit.

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

Abstract: An induction heating apparatus is capable of stop heating without excessively boosting output voltages of a booster circuit and a power factor correction circuit. The induction heating apparatus includes a boosting function unit, an inverter circuit, and a booster circuit controller. The boosting function unit includes a power factor correction circuit and a booster circuit, and boosts an input direct-current power to a direct-current voltage having a peak value larger than the peak value of the input direct-current power by turning on/off a switching element. The inverter circuit includes a heating coil, and inputs the direct-current voltage output by the boosting function unit to generate a high frequency current in the heating coil by turning on or off a different switching element. The booster circuit controller stops a boosting operation of the boosting function unit without a prescribed delay from the stop of an operation of the inverter circuit.

Abstract: A method and apparatus for power conversion. In one embodiment, the apparatus comprises at least two power stages, each power stage of the at least two power stages capable of converting DC input power to DC output power; and a controller for dynamically selecting, based on a first DC power, one or more power stages of the at least two power stages for converting the first DC power to a second DC power.

Abstract: An exemplary embodiment of a power converter is provided. The power converter includes a transformer, a power device, a switching controller, and a capacitor. The power device is coupled to the transformer for switching the transformer to product output of the power converter. The switching controller receives a feedback signal for generating a switching signal coupled to drive the power device. An input circuit of the switching controller is coupled to the transformer to sample an input signal for generating the feedback signal, and the input signal is correlated to the output of the power converter. The capacitor is coupled to the switching controller to provide frequency compensation for a feedback loop of the power converter. Input of the power converter is without an electrolytic capacitor, and a maximum output current of the power converter is a constant current.

Abstract: A switching power supply apparatus including: a switching DC-DC converter for receiving an input voltage; a current detecting unit for detecting a current from the DC-DC converter; an input voltage detecting unit for detecting the decrease or cutoff of the input voltage; an overcurrent limiting circuit for stopping the operation of the DC-DC converter when the current detected by the current detecting unit exceeds a threshold; and a threshold control unit for changing the threshold of the overcurrent limiting circuit such that, if the decrease or cutoff of the input voltage is detected by the input voltage detecting unit, the period between the time when the decrease or cutoff of the input voltage is detected and the time when the operation of the DC-DC converter is stopped is prolonged.

Abstract: Embodiments of the invention relate to a power system for converting direct current (“DC”) power on a DC bus into alternating current (“AC”) power with a regulated voltage output and for feeding the AC power to an electrical system which may include a power utility or an electric grid, for example. A power conversion control system is used for controlling the power conversion and for maintaining the DC bus voltage (“DC voltage”) at a certain level.

Abstract: Methods and apparatuses for programming a parameter value in an IC (e.g., any power electronic device, such as a controller of a power converter) are disclosed. The parameter can be selected/programmed by selecting a clamp using an external optional (selectively inserted) diode coupled to a multi-function programming terminal. In particular, a controller IC for a power converter can be externally programmed via one or more multiple function terminals during startup of the converter to select between two or more options using the external programming terminal(s). Once programming is complete, internal programming circuitry may be decoupled from the programming terminal and during normal operation the programming terminal may then be used for another function, such as a bypass (BP) terminal to provide a supply voltage to the IC or other required functionalities.

Abstract: An example method of controlling a power supply to have a constant current output includes receiving an input current sense signal, an input voltage sense signal, and an output voltage sense signal. A control signal is then generated to control switching of a switch of the power supply to regulate an output current of the power supply. The generating of the control signal includes integrating the input current sense signal during a switching period of the control signal to generate an integrated signal representative of a charge taken from an input voltage source of the power supply. Generating the control signal also includes controlling the switching of the switch such that the integrated signal is proportional to a ratio of the output voltage sense signal to the input voltage sense signal.

Abstract: A power transfer system provides power factor conditioning of the generated power. Power is received from a local power source, converted to usable AC power, and the power factor is conditioned to a desired value. The desired value may be a power factor at or near unity, or the desired power factor may be in response to conditions of the power grid, a tariff established, and/or determinations made remotely to the local power source. Many sources and power transfer systems can be put together and controlled as a power source farm to deliver power to the grid having a specific power factor characteristic. The farm may be a grouping of multiple local customer premises. AC power can also be conditioned prior to use by an AC to DC power supply for more efficient DC power conversion.

Abstract: A power conversion apparatus includes a power converter and a PWM controller. A first switching element is coupled to a positive pole of a DC power source and one terminal of a load. A second switching element is coupled to a negative pole of the DC power source and another terminal of the load. A third switching element is coupled to the positive pole and the other terminal. A fourth switching element is coupled to the negative pole and the one terminal. The PWM controller PWM-controls the power conversion apparatus to repeat an on-period during which the DC power source outputs a voltage to the load and an off-period during which no voltage is output. The PWM controller alternately controls the first and second switching elements based on a signal set at a high or low level any time during a carrier wave period.

Abstract: A power converter module is disclosed, which is an all-digital module. The power converter module includes a reference voltage generation unit, a voltage loop control unit, a current loop control unit, an input voltage compensation unit, and a pulse width modulation generation unit, to transfer input power to stable output power for providing power to an external loading device through driving bridge switch unit with external driver. The voltage loop control unit and the current loop control unit contain a proportion-integral-differentiation controller for receiving signal related to voltage and current of loading device to form voltage control loop and current control loop. The pulse width modulation generation unit contains function of deciding necessary stop time to improve quality of output power and decrease the effect of input power and loading variation, and to provide stable sine-waveform output power to the external loading device.

Abstract: This invention relates to a LLC resonant converter for full input voltage range and its control method. The full voltage range LLC resonant converter comprises a LLC resonant converter circuit, a current type main loop current sampler, a rectifier, a main loop energy quantifier, an energy comparator, a return-to-zero pulse generator, an oscillator, and a split phase controller. The LLC resonant converter is configured to turn on electronic switches with ZVS state in full input voltage range. This invention realizes the full voltage working range of LLC resonant converter, guarantees its reliability, and enables designing a LLC converter to be a solid state converter. The LLC resonant converter can be widely used in applications such as non-contact charging stations for electric vehicle, electromagnetic inductance heating and switch power.

Abstract: According to some preferred embodiments, power converter includes a comparator circuit with feedback from current-fed PI or PID control to select one of two regeneration times of at least one active clamp: i) wherein at low loads a regeneration circuit is turned ON for substantially an entire current-transfer cycle such as to avoid output of current-fed converter continuing to rise; and ii) wherein at high loads the regeneration period is reduced to between about ¼ to ½ of a resonance-frequency cycle so that a resonance between the regeneration capacitance and the transformer's leakage inductance avoids excessive ringing currents and/or lost efficiency.

Abstract: An AC converter includes: a switching section, which converts the input AC voltage in response to a control signal and which outputs the converted voltage to a phase that has been selected in accordance with the control signal; a filter section, which filters out high frequency components from the converted voltage, thereby converting the converted voltage into the output AC voltage; and a switching control section, which performs a pulse density modulation on a phase-by-phase basis and in response to a reference signal with the frequency f1, which is associated with the output AC voltage of each phase, synchronously with a zero cross of the input AC voltage, thereby generating the control signal according a pulse generation status by the pulse density modulation and the polarity of the input AC voltage and sending out the control signal to the switching section.

Abstract: There is disclosed a power supply stage, comprising: generating means for generating a power supply voltage from a high efficiency variable voltage supply in dependence on a reference signal; adjusting means for receiving the generated power supply voltage, and adapted to provide an adjusted selected power supply voltage tracking the reference signal in dependence thereon.

Abstract: An inverter control is used to control the output of a distributed power generating station, such as a photovoltaic (PV) solar power station, connected to a power grid. The power station is connected to an inverter output. Pulse width modulation is used to shape the output in order to maximize power output within power quality parameters and provides control of a switching frequency of the inverter responsive to a sensed parameter. The technique allows an increase in output efficiency and provides for adjustment of power output to meet power quality parameters to an extent required in order to connect to the power grid.

Abstract: A power conversion apparatus includes a power converter, a voltage detector, a current detector, a detection voltage adjustor, and a controller. The power converter is configured to convert power from a power source into alternating-current power and is configured to output the alternating-current power to a power system. The voltage detector is configured to detect a voltage of the power system. The current detector is configured to detect a direct-current component of a current between the power converter and the power system. The detection voltage adjustor is configured to add a bias corresponding to the direct-current component to the voltage detected by the voltage detector, so as to generate a voltage detection signal, and is configured to output the voltage detection signal. The controller is configured to control the power converter to output an alternating-current voltage corresponding to the voltage detection signal.

Abstract: The present invention provides an apparatus for controlling a multiphase multilevel voltage source inverter. The apparatus includes a signal-generating unit and a converter. The signal-generating unit responds to an input signal to produce a switching strategy control signal and a duration timing control signal corresponding to the switching strategy control signal. The converting unit responds to the switching strategy control signal and the duration timing control signal to produce a switching signal. The voltage source inverter responds to the switching signal to generate a multiphase-and-multilevel AC voltage output.

Abstract: The power supply according to the present invention comprises a transformer, a power switch, a signal generating circuit, an on-time detection circuit, and a delay circuit. The transformer receives an input voltage and generates an output voltage. The power switch switches the transformer for regulating the output voltage. The signal generating circuit generates a switching signal for controlling switching of the power switch. The on-time detection circuit detects an on-time of the power switch and generates a short-circuit signal. The delay circuit counts to a first delay time or to a second delay time in response to a feedback signal of the power supply and the short-circuit signal to generate a turn off signal for controlling the signal generating circuit to latch the switching signal.

Abstract: The present invention relates to a near zero current-ripple inversion circuit including top and bottom cells, a transformer (T1) comprising primary windings (P1, P2) and a secondary winding (S1), and at least one middle cell connected in series between the top and bottom cells. The top cell comprises two capacitors (C1, C2) and a switch (Q1) each connecting to the middle cell, and an inductor (Lr1) and the primary winding (P1) connected in series between the capacitor (C1) and switch (Q1), wherein the switch (Q1) is connected to the capacitors (C1, C2) respectively. The bottom cell comprises a capacitor (C3) and a switch (Q2) each connecting to the middle cell, and an inductor (Lr2) and the primary winding (P2) connected in series between the capacitor (C3) and switch (Q2), wherein the primary winding (P2) is connected to the middle cell, and the capacitor (C3) and switch (Q2) are connected.

Abstract: A photovoltaic inverter includes an input circuit, a decoupling circuit and an output circuit. The input circuit has a DC input port, an input capacitor, a magnetizing inductor, a first unidirectional element and a first switch. The magnetizing inductor forms first and second connection nodes. The decoupling circuit has a second unidirectional element, a second switch, a third switch, a third unidirectional element and a decoupling capacitor. The second unidirectional element and the second switch are connected in series at a first node. The third switch and the third unidirectional element are connected in series at a second node. The output circuit has a transformer, a fourth unidirectional element, a fourth switch, an output capacitor, a fifth switch, a fifth unidirectional element, an output inductor and an AC output port. The transformer includes an input port and first and second output ports. A control method of the inverter is disclosed.

Abstract: A direct current to alternating current converter method and apparatus is disclosed that may comprise a direct current (DC) input source; an alternating current (AC) output inverter circuit, having an input connected across the DC input source; a partial power DC-DC boosting circuit intermediate to the DC input source and the DC input of the inverter stage, configured to increase the input voltage of the DC input source whenever the input voltage falls below a minimum required to synthesize an output waveform of a selected shape and a partial power DC-DC boosting circuit intermediate to the DC input source and the DC input of the inverter stage, configured to increase the input voltage of the DC input source during higher amplitude portions of inverter circuit output voltage waveform.

Abstract: There is provided a method and control system for reducing noise in a power converter by controlling a switching device in the power converter according to a modulation scheme. The switching device couples a direct current (DC) source to provide an alternating current (AC) output at a particular switching frequency. The method comprises the step of, in each switching period, switching the switching device between active configurations providing a finite voltage at the output and inactive configurations providing a zero voltage at the output. The ratio between the total period of time in which the switching device is in an active configuration and the total period of time in which the switching device is in an inactive configuration is the same for each switching period and is determined according to the desired voltage at the AC output.

Abstract: An energy efficient apparatus includes a switching device, a frequency dependent reactive device, and a control element is provided. The switching device is coupled to a source of electrical power and includes a pair of transistors and is adapted to receive a control signal and to produce an alternating current power signal. The frequency of the alternating current power signal is responsive to the control signal. The frequency dependent reactive device is electrically coupled to the pair of transistors for receiving the alternating current power signal and producing an output power signal. The frequency dependent reactive device is chosen to achieve a desired voltage of the output power signal relative to the frequency of the alternating current power signal. The control element senses an actual voltage of the direct current power signal and modifies the control signal delivered to achieve the desired voltage of the direct current power signal.

Abstract: Among many embodiments, a power conversion apparatus and a method for converting power are disclosed. The power conversion apparatus may include switching components configured to create an alternating current; a preemptive detector arranged and configured to provide, in advance of the alternating current reaching a zero-crossing, a control signal responsive to the alternating electrical current approaching the zero-crossing; and a controller configured, at least in part, to change a state of the switching components before the zero crossing, in response to the control signal.

Abstract: A power module includes a substrate including an insulating member and a patterned metallization on the insulating member. The patterned metallization is segmented into a plurality of spaced apart metallization regions. Adjacent ones of the metallization regions are separated by a groove which extends through the patterned metallization to the insulating member. A first power transistor circuit includes a first power switch attached to a first one of the metallization regions and a second power switch attached to a second one of the metallization regions adjacent a first side of the first metallization region. A second power transistor circuit includes a third power switch attached to the first metallization region and a fourth power switch attached to a third one of the metallization regions adjacent a second side of the first metallization region which opposes the first side. The second power transistor circuit mirrors the first power transistor circuit.

Abstract: A power converter controller includes a drive circuit coupled to control switching of a power switch coupled to an energy transfer element and an input of the power converter. An output voltage sensor including first and second pulse sampler circuits is coupled to capture first and second peak voltages, respectively, that are representative of a second peak of a ringing voltage of a feedback signal representative of an output of the power converter. The first pulse sampler circuit is coupled to capture the first peak voltage at a first time in the feedback signal. The second pulse sampler circuit is coupled to capture the second peak voltage at a second time in the feedback signal. The drive circuit is coupled to receive a change signal from the output voltage sensor in response to the first and second peak voltages.

Abstract: Improving start-up time of a light emitting diode (led) driver at lower input voltage is accomplished with a quick start circuit comprising a constant current source that replaces the traditional trickle charge start-up path for charging of a Vcc capacitor supplying operating voltage to an SMPS controller. Also the constant current source will only be operational during SMPS start-up, then will turn off after the SMPS is capable of producing its own regulated power supply to the Vcc terminal of the SMPS controller, thereby minimizing E2/R power losses in the SMPS.

Abstract: A power converter for delivering power to a load at a regulated voltage 11 includes a regulating stage receiving an unregulated supply 10 and having a main transformer 18. Switches 16a and 16b are arranged in a half-bridge connect the transformer primary 17 to the unregulated supply 10 to drive the load via a rectifying stage connected to the transformer secondary 19. The on-time of the switch is controlled by a controller 14 to effect the regulation over a range of values of the unregulated supply. An auxiliary transformer 103 has a secondary winding 104 connected in series with the main transformer primary 17 and a primary winding that is selectively driven via a switch 106. A comparator 107 detects a low voltage event within the regulating stage, such as a drop in the intermediate voltage at 10. The primary winding 105 of the auxiliary transformer 103 is driven during the low voltage event.

Abstract: A power converter includes a dc input having first and second terminals. A main converter is coupled to the first terminal of the dc input. A standby circuit coupled to the second terminal of the dc input and the main converter. The main converter is coupled to control a transfer of energy from the dc input through the standby circuit to a main output of the main converter during a normal operating condition of the power supply. The standby circuit is coupled to decouple the main converter from the second terminal of the dc input during a standby operating condition of the power converter. A standby converter is coupled to the first and second terminals of the dc input to control a transfer of energy from the dc input to a standby output of the standby converter during the standby operating condition of the power converter.

Abstract: A power supply apparatus for LED is provided. The power supply apparatus for LED includes a detector, a voltage dropper, and a control switch. The detector detects whether an LED is connected to the power supply apparatus. The voltage dropper drops a voltage applied to the LED. The control switch is connected to the voltage dropper in parallel, and changes a path of a power applied to the LED according to the detected result of the detector. Accordingly, the power supply apparatus for LED compensates for a low impedance of an LED to an impedance equal to or higher than a predetermined impedance at a time when connection of the LED is detected, thereby inhibiting an overcurrent from flowing in the LED.

Abstract: A switched-mode power supply includes a soft-burst circuit to minimize or prevent distracting audible noise. The power supply includes a control circuit for controlling switching of an output transistor to deliver a regulated output voltage to a load. The control circuit adjusts the operating frequency of the power supply based on a control signal. The soft-burst circuit discharges a storage device to minimize or prevent audible noise when the control signal reaches a particular level.