Abstract: A switching power supply includes a source of DC voltage and a transformer having primary and secondary windings. A switching circuit is coupled between the DC voltage and the primary winding to provide alternating current to the primary winding. A rectifier circuit is coupled to the secondary winding to provide a DC output voltage. A controller circuit controls the switching circuit to modulate the alternating current provided to the primary winding. A circuit receives a first input signal having a magnitude which is determined by the DC output voltage and a second input signal having a magnitude which is determined by a selected position of a multiposition switch. An output of the circuit generates a feedback signal which is coupled to the controller circuit.

Abstract: For the purpose of providing a resonant switching power supply device having a wide output voltage variable range by changing its switching frequency, the resonance circuit thereof comprises a switching transformer, a first resonance section connected in series with the switching transformer, and a second resonance section connected in parallel with the switching transformer, wherein the resonance frequency characteristic in the case that the DC load current is large is formed using the series-connected devices of the first resonance section, and the resonance frequency characteristic in the case that the DC load current is small is formed using the first resonance section, the second resonance capacitor of the second resonance section and the switching transformer.

Abstract: A DC/DC converting system, comprising: a DC/DC converter adapted to convert an input voltage to a second output voltage; and a charge pump adapted to provide an operation voltage to the DC/DC converter. According to embodiments of the present invention, a DC/DC converter having a large operation voltage range can be implemented by connecting a charge pump with a DC/DC converter and using the first output voltage of the charge pump as the operation voltage of the DC/DC converter. Moreover, by connecting at least one back-to-back diode switch between the power supply terminal and the first output terminal of the first DC/DC converting circuit of the charge pump, a first output voltage may be output stably as the operation voltage of the DC/DC converter when different input voltages are input to the power supply terminal.

Abstract: A circuit and method for controlling a switching regulator utilize a combination of variable off-time control (or frequency control) and variable peak current control to achieve high efficiency at a wide range of load conditions. A non-linear control circuit receives an error voltage and generates a first control signal for controlling a frequency control circuit and a second control signal for controlling a peak current control circuit. The frequency control circuit and the peak current control circuit operate in conjunction over the entire range of load conditions with the frequency control dominates at light load (or low power) conditions and the variable peak current control dominates at moderate to heavy load (or high power) conditions. The switching regulator transitions smoothly between frequency control and peak current control with continous loop gain throughout the transition region.

Abstract: The SOC of a battery is calculated based on the voltage Vb and current Ib of a battery, and a battery electromotive voltage Vbo is calculated based on the SOC of the battery. Based on the battery electromotive voltage Vbo and the voltage Vc of a capacitor connected on the output side of the DC/DC converter, a duty ratio D(=Vbo/2Vc) achieving the maximum battery power is set as the lower limit value DL of the optimum duty range DR, so that the lower limit value DL is varied according to the SOC of the battery. The duty ratio D is limited so as to fall within the optimum duty range DR, and the DC/DC converter is controlled to be driven using the limited duty ratio D.

Abstract: A LED-based lamp apparatus includes a LED unit having multiple LEDs connected in series, a step-up circuit for stepping up a power supply voltage by a switching action of a switching element to supply an electric current to the LED unit, a sensing element for measuring a value of the current, and a controlling element connected in series with the LED unit to control the current based on the measured current value. When some of the LEDs of the LED unit are broken and short-circuited due to, for example, long-term use, the current increases instantaneously and an overcurrent condition occurs. In this case, the controlling element limits the current immediately to correct the overcurrent condition. Thus, the controlling element prevents the overcurrent condition from causing a secondary failure to normal LEDs of the LED unit.

Abstract: The invention relates to a converter circuit, in particular having a class E converter, having an improved drive circuit for a switching transistor MOS1 having two series-connected components which operate as a function of the threshold value, in particular comparators K1, K1? and K2, K2?.

Abstract: A power converter receiving a single-sided supply which is ground-terminated and providing a regulated positive supply and a regulated negative supply that is optimized to the expected output range of a class AB amplifier, as well as providing excellent efficiency. The converter finds application as a compact converter to power an audio amplifier driving an audio device which is ground terminated, such as a speaker.

Abstract: Disclosed is a power adapter having a voltage limiting circuit for limiting an output voltage of the power adapter at a predetermined voltage level when an output current of the power adapter is smaller than a threshold current, and a power limiting circuit for limiting an output power of the power adapter at a predetermined power level when an output current of the power adapter reaches the threshold current, in which the voltage limiting circuit can be configured to receive a current control signal from a load and in response thereto issue a load current regulation signal to a switching control circuit of the power adapter, thereby regulating the output voltage of the power adapter based on the load current regulation signal.

Abstract: The present invention provides a synchronous switching control circuit for variable switching frequency power converters. It comprises a first circuit to generate a first signal in response to an input synchronous signal of a power converter. A second circuit is coupled to the first circuit to generate a second signal in accordance with the frequency of the first signal. Only when the first signal is operated in a specific frequency range, the synchronous operation is allowed. An oscillation circuit is connected to the first circuit and the second circuit to receive the first signal and the second signal to generate an oscillation signal. The oscillation signal is utilized to enable the switching signal of the power converter. The switching signal is thus synchronized with the input synchronous signal in response to the enable of the second signal. Otherwise, the switching signal will be free running.

Abstract: A power supply system including an external power supply unit generating direct-current output voltage and an electronic device connected to the external power supply unit and operable on the output voltage of the external power supply unit. The external power supply unit includes a voltage control circuit receiving control current and controlling the output voltage of the external power supply unit in accordance with the control current. The voltage control circuit controls the output voltage of the external power supply unit to be equal to the minimum voltage possible for the external power supply unit to generate when the control current is minimum.

Abstract: A level-shift circuit for use with a half bridge in accordance with an embodiment of the present application includes an oscillator operable to provide a timing signal, a level-shift switch controlled by the timing signal of the oscillator, a high side control circuit operable to provide a high side control signal to a high side switch of the half bridge to control the high side switch and a low side control circuit operable to provide a low side control signal to a low side switch of the half bridge to control the low side switch. The level-shift switch is turned ON when the timing signal is high such that the level-shift switch connects the high side control circuit to ground and the high side control signal stays low to keep the high side switch OFF when the timing signal is high. The low side control circuit provides the low side control signal to turn the low side switch ON a predetermined period of time after the timing signal goes high.

Abstract: A method and apparatus for controlling a power supply. The system includes a power supply and a controller for outputting a command signal to regulate the operation of the power supply. The controller determines the command signal based on at least one error signal which is selected from a plurality of error signals based on a selection criterion.

Abstract: Power factor correction circuits are provided, in which a boosting converter comprises a switching element and an inductor, to convert a rectified voltage to a DC output voltage. An adjustment unit comprises a thermister with positive temperature coefficient, to generate an adjustment signal according to a present temperature and the DC output voltage. A control unit controls a duty cycle of the switching element according to the adjustment signal, thereby adjusting the voltage difference between the rectified voltage and the DC output voltage.

Abstract: A PFC AC-to-DC power supply is disclosed. According to various embodiments, the PFC AC-to-DC power supply comprises a switching converter comprising at least one main power switch and a PFC controller for controlling the at least one main power switch. The PFC controller may comprise a processing unit comprising a processor and a memory having firmware stored thereon which, when executed by the processor, causes the processor to compute an input current set point for the AC-to-DC power supply based on the output voltage of the AC-to-DC power supply. The PFC controller may also comprise hardware circuitry in communication with the processing unit. The hardware circuitry may comprise a first a/d converter, such as a window a/d converter, for outputting a digital input current error value based on the input current of the AC-to-DC power supply and an analog form of the input current set point from the processing unit.

Abstract: A programmable power supply for providing a regulated DC output power is disclosed. The power supply provides the output power to any one of a plurality of electronic devices adapted for receiving the output power at an operational voltage or an operational current. The power supply receives a programming signal to maintain the output power at the operational voltage or operational current associated with a particular selected electronic device. Accordingly, by varying the programming signal, the power supply can be programmed to provide output power to any one of several electronic devices having differing input power requirements.

Abstract: A method and apparatus for controlling a power supply. The system includes a power supply and a controller for outputting a command signal to regulate the operation of the power supply. The controller determines the command signal based on at least one error signal which is selected from a plurality of error signals based on a selection criterion.

Abstract: Circuits and methods to sense the current through a coil of an integrated switching converter, applicable to boost and to buck converters, have been achieved. The present invention uses a “replica biasing” technique to avoid a resistor for current measurement. The current through a pass device is mirrored into a replica, having a scale of n and being much smaller in size, of said pass device. The current through the replica is mirrored to another branch of the circuit and back again to achieve a fast stabilization of the current. The current through the replica is mirrored again to an output branch of the circuit, which conducts exactly a fraction 1/n of the current flowing through the pass device. The self-biasing current loop of the invention adapts quickly to the actual current level through the pass device of the switching converter. Accuracies better than 5% are achieved over a wide range of dynamic range.

Abstract: By using a target voltage Vc* of a capacitor connected to the output side of a DC/DC converter and a voltage Vb of a battery connected to the input side of the DC/DC converter, a duty ratio D as a drive instruction of the DC/DC converter is calculated. By using the voltage Vb, the electromotive force Vbo of the battery, and the charge/discharge current Ib of the battery, an internal resistance Rb is calculated. According to the internal resistance Rb and the electromotive force Vbo, the current value when the battery output becomes maximum is set as the upper limit value of the optimal current range IR, the DC/DC converter is driven/controlled by limiting the duty ratio D so that the current Ib is within the range of the optimal current range IR. Thus, it is possible to appropriately convert the battery input voltage.

Abstract: A power supply system includes a power source and a control circuit. The power source provides DC power. A control circuit, which is remote to the power source, receives the DC power and provides a first DC power signal to an electronic device. The control circuit includes an active component to provide at least one of a voltage control output or a current control output to the power source to regulate the DC power. A power supply system includes a power source and a control circuit. The control circuit is remote to the power source, receives the DC power, and provides the DC power to an electronic device. The control circuit includes a microprocessor to provide at least one of a voltage control output and a current control output to the power source to regulate the DC power.

Abstract: A method of producing a photovoltaic panel that includes elementary photovoltaic cells in series and in parallel and intended for charging a low-voltage electrical energy accumulator via a voltage converter includes wiring a minimum number of elementary cells in series between the two terminals of the photovoltaic panel. The minimum number is established such that, under a given illumination, the knee voltage of the photovoltaic panel is greater than the threshold voltage of operation of the converter. The invention also relates to a device for charging a low-voltage accumulator via a converter comprising a photovoltaic panel obtained by this method.

Abstract: A synthetic rectifier comprises a MOSFET and a control circuit to turn the MOSFET off and on as a synchronous rectifier. The control circuit senses the current through the synthetic rectifier, and in particular is responsive to the rate of decrease of the current so as to anticipate when the current goes to zero and turn off at that instant. The control circuit also senses the voltage across the synthetic rectifier, and in particular is responsive to the rate of decrease of the voltage so as to anticipate when the voltage goes to zero and turn on the synthetic rectifier at that instant. In another embodiment of the invention, the MOSFET comprises groups of cells that can be individually controlled. As the current is decreasing, groups of cells can be turned off progressively as the current decreases so that only a small number of cells which can be turned off very fast is still conducting as the current goes to zero.

Abstract: A switching regulator includes a compensation circuit for applying a scaling factor to the loop gain of the feedback control loop of the regulator. In operation, the loop gain of the feedback control loop has a dependency on the input and output voltages of the switching regulator. The compensation circuit applies a function as the scaling factor where the function is a reciprocal function of the loop gain dependency on the input voltage and output voltage. In one embodiment, the loop gain has a dependency on the ratio VIN/VOUT and a scaling factor having a value indicative of the ratio VOUT/VIN is applied by the compensation circuit. In one embodiment, the compensation circuit is coupled in series with the output circuit of an error amplifier in the feedback control loop of the regulator. In another embodiment, the compensation circuit is subsumed within the circuitry of the error amplifier.

Abstract: An electrical circuit for providing a temperature compensated feedback signal includes a first electrical component and a first amplifier. The first electrical component exhibits a first temperature variable impedance and is positioned in thermal contact with a first switch having a second temperature variable impedance. The first amplifier includes an input electrically coupled to the first switch and an output electrically coupled to an input of the first electrical component. The first amplifier amplifies the signal produced across the first switch when the first switch is conducting and the first electrical, component attenuates the amplified signal provided by the first amplifier as a function of a temperature of the first electrical component. The attenuated amplified signal is provided at an output of the first electrical component to provide a temperature compensated feedback signal.

Abstract: A progammable power supply for providing a regulated DC output power is disclosed. The power supply provides the output power to any one of a plurality of electronic devices adapted for receiving the output power at an operational voltage or an operational current. The power supply receives a programming signal to maintain the output power at the operational voltage or operational current associated with a particular selected electronic device. Accordingly, by varying the programming signal, the power supply can be programmed to provide output power to any one of several electronic devices having differing input power requirements.

Abstract: A method and system for dynamic limiting of the pulse width or duty cycle of a switched DC-to-DC power supply. The system includes a first comparator coupled to the voltage to be regulated and to a reference voltage for generating an error signal. The error signal controls the duty cycle or pulse width of a PWM. A limiter circuit includes a further comparator which compares the error signal to a second reference voltage to generate a further limiting feedback signal for application to the first comparator. When the error signal tends to rise above a value established by the second reference voltage, the limiter applies a signal to the first comparator tending to reduce the error signal to thereby prevent the error signal from rising sufficiently to produce the undesired operating condition.

Abstract: A primary-side flyback power converter supplies a constant voltage and a constant current output. To generate a well-regulated output voltage under varying load conditions, the power converter includes a PWM controller. The PWM controller generates a PWM signal to control a switching transistor in response to a flyback voltage detected from the first primary winding of the power supply transformer. To reduce power consumption, the flyback energy of the first primary winding is used as a DC power source for the PWM controller. The flyback voltage is sampled following a delay time to reduce interference from the inductance leakage of the transformer. To generate a more accurate DC output voltage, a bias current is pulled from the detection input to form a voltage drop across a detection resistor for compensating for the voltage drop of the output rectifying diode.

Abstract: An inverter for igniting a discharge lamp comprises a transformer, a first switch transistor, a second switch transistor, a first snubber capacitor, a second snubber capacitor, a reset capacitor, and a control circuit. One of the source/drain of the first switch transistor is electrically coupled to the primary side of the transformer. One of the source/drain of the second switch transistor is electrically coupled to the primary side of the transformer. The first snubber capacitor is electrically coupled between the source and the drain of the first switch transistor. The second snubber capacitor is electrically coupled between the source and the drain of the second switch transistor. The reset capacitor is electrically coupled between the other of the source/drain of the first switch transistor and the other of the source/drain of the second switch transistor.

Abstract: A power converter with high efficiency, low component count, and high step down conversion capability. The converter has a full bridge circuit connected to a pair of buck output circuits. The full bridge circuit and buck circuits are not isolated. In one embodiment, a transformer is connected between the full bridge and buck circuits without providing isolation. In operation, the transformer is operated as an autotransformer, which results in reduced voltages and currents applied to the switches. As a result, the present invention is capable of reduced switching losses, lower output voltage and other benefits. The present invention also includes an embodiment having coupled inductors instead of a transformer. Also, the present invention includes embodiments having additional parallel buck output circuits for higher power and higher current capability.

Abstract: A switching regulator includes at least two power switches and two rectifier switches, power transformer having a primary and secondary windings, control circuit for generating control pulses for the power switches, an inductor for providing output current to the load and connected, and a current sensor coupled to the secondary windings and the inductor for sensing current passing through the inductor. The current sensor preferably includes a first and second resistor and a capacitor connected together, and provides a sensed voltage at its output proportional to the product of output current of the inductor and inherent DC resistance of the inductor and the secondary windings. The current sensor is coupled to the control circuit for regulation and protecting the switching regulator against overload or short circuit conditions.

Abstract: An input circuit that detects an abnormality of a voltage generation of the input circuit. The circuit includes an external output terminal, an analog voltage generator. The generator includes a power supply terminal, a grounding terminal, and an internal output terminal. The circuit includes a first resistor, which is connected to the power supply and to the power supply terminal, a second resistor, which is connected to the ground and to the grounding terminal, a third resistor, which is connected to the internal output terminal and to the external output terminal, and a fourth resistor, which is connected to the node of the third resistor and the external output terminal and to the ground. When the grounding terminal or the power supply terminal is open, the analog voltage of the external output terminal is in an upper limit fail voltage range or in a lower limit fail voltage range.

Abstract: A self-driven synchronous rectification circuit which includes two power switches S1 and S2; a transformer Tr having a primary winding Np, a secondary winding Ns and an auxiliary winding Na; two secondary synchronous rectifiers S3 and S4; two diodes D1 and D2; two switching transistors Q1 and Q2; and two zener diodes ZD1 and ZD2. The number of auxiliary winding turns Na of the transformer Tr ensure that the synchronous rectifiers S3 and S4 are supplied with an adequate gate-drive voltage. When S3 conducts, the gate-drive voltage of S4 is clamped by D1 and Q1. Likewise, when S4 conducts, the gate-drive voltage of S3 is clamped by D2 and Q2. ZD1 and ZD2 operate to restrain the gate over voltage of S3 and S4, respectively. When the gate drive voltage of S4 is clamped by D1 and Q1, Q2 disables D2 and when the gate drive voltage of S3 is clamped by D2 and Q2, Q1 disables D1.

Abstract: A power supply unit includes a transformer converting an input voltage into a predetermined output voltage, a transistor controlling a current flowing through a primary winding of the transformer, an output voltage detecting circuit detecting an output voltage of the power supply unit and outputting a detection signal corresponding to-a level of the output voltage, a control circuit controlling the output voltage by switching on and off the transistor in accordance with the detection signal, and an operation control circuit controlling an operation of the control circuit in accordance with the output voltage

Abstract: An active filter is coupled to a dc line of a converter such as a dc-dc converter. The active filter traps a harmonic frequency component of chopped current on the dc line. A passive EMI filter may also be coupled to the dc line to remove higher harmonic frequency components of the chopped current on the dc line.

Abstract: An AC to DC converting apparatus is disclosed. In the Ac to DC converting apparatus, a first adder adds an output voltage from a rectifying unit to a voltage depending on an output current from the rectifying unit. A current controller outputs a current control signal based on an added result from the first adder. A second adder adds a preset reference voltage to an output voltage from the switching unit. A voltage controller outputs a voltage control signal, and a third adder adds the output voltage from the rectifying unit to a duty reference voltage. A fourth adder adds the voltage control signal to an output voltage from the third adder. A signal limiting unit compares the current control signal with an output signal from the fourth adder, and outputs a compared result as an output signal. A PWM unit generates a PWM signal in response to the output signal from the signal limiting unit.

Abstract: An electric vehicle drive has an electric machine which can be alternatively driven as a motor or as a generator and has a d.c. connection to which a supply voltage can be applied, from a first energy source and/or a second energy source. The first energy source is designed for base load supply of the electric machine, while the second energy source comprises an energy accumulator designed for a short-term peak load supply of the electric machine. Also, vehicle braking energy can be stored by way of the electric machine in its generator operating mode. According to the invention, the second energy source in the form of an energy accumulator is coupled via a bidirectional DC/DC converter to a supply connection of the first energy source connected with the direct-voltage connection of the electric machine.

Abstract: For use with a synchronous rectifier coupled to a secondary winding of a transformer and having a rectifier switch, a circuit for, and method of driving the rectifier switch and a power converter employing the circuit or the method. In one aspect of the present invention wherein the synchronous rectifier has at least first and second rectifier switches, the circuit includes: (1) a series-coupled drive winding and capacitor, coupled between a first control terminal of the first rectifier switch and a second control terminal of the second rectifier switch, that generates first and second drive signals and delivers the first and second drive signals to the first and second control terminals, respectively, and (2) first and second clamps, coupled to the first and second control terminals, respectively, that control first and second capacitive charges within the first and second rectifier switches to limit voltage excursions of the first and second drive signals.

Abstract: The present invention relates to an electric power unit with a condenser input type rectification circuit which converts an alternating current power source to a direct current voltage, and more particularly, to an electric power unit for inverter-controlled refrigerators. An electric power unit according to the present invention feeds electric power to a load (7), which comprises an alternating current power source (1), a bridge-type rectification circuit (2) having an input from the alternating current power source (1) and consisting of bridge-connected diodes (D1, D2, D3, D4), an auxiliary capacitor (3) connected in parallel to an output of the bridge-type rectification circuit (2), a series circuit of a reactor (4) and a diode (5) connected between one output of the bridge-type rectification circuit (2) and the load (7) so as to flow a load current in a forward direction, and a smoothing capacitor (6) connected in parallel to the load (7).

Abstract: A power supply device for supplying power to an electronic apparatus with a power saving mode includes a rectifier circuit for converting an AC input voltage Vin to a DC voltage, a boost circuit for boosting the DC voltage to a prescribed level, a power factor correction (PFC) circuit for correcting the power factor of the output voltage of the boost circuit according to a feedback voltage from the output of the boost circuit, and a disable circuit for disabling the power factor correction (PFC) circuit in a power saving mode, whereby the power consumption is prevented for a switching operation of the power factor correction (PFC) circuit in the power saving mode.

Abstract: The present invention relates to an electric power unit with a condenser input type rectification circuit which converts an alternating current power source to a direct current voltage, and more particularly, to an electric power unit for inverter-controlled refrigerators.An electric power unit according to the present invention feeds electric power to a load (7), which comprises an alternating current power source (1), a bridge-type rectification circuit (2) having an input from the alternating current power source (1) and consisting of bridge-connected diodes (D1, D2, D3, D4), an auxiliary capacitor (3) connected in parallel to an output of the bridge-type rectification circuit (2), a series circuit of a reactor (4) and a diode (5) connected between one output of the bridge-type rectification circuit (2) and the load (7) so as to flow a load current in a forward direction, and a smoothing capacitor (6) connected in parallel to the load (7).

Abstract: A low quiescent current draw regulator comprising a low output conductance device for receiving a variable DC input voltage and for providing a first nominal quiescent constant current through a serially connected resistor and a reference diode, and a circuit coupled across the resistor and reference diode for providing a substantially regulated output voltage.

Abstract: For use with a synchronous rectifier coupled to a secondary winding of a transformer and having a rectifier switch, a circuit for, and method of driving the rectifier switch and a power converter employing the circuit or the method. In one aspect of the present invention wherein the synchronous rectifier has at least first and second rectifier switches, the circuit includes: (1) a series-coupled drive winding and capacitor, coupled between a first control terminal of the first rectifier switch and a second control terminal of the second rectifier switch, that generates first and second drive signals and delivers the first and second drive signals to the first and second control terminals, respectively, and (2) first and second clamps, coupled to the first and second control terminals, respectively, that control first and second capacitive charges within the first and second rectifier switches to limit voltage excursions of the first and second drive signals.

Abstract: A power supply device provides high voltage power from a low voltage source. The power supply device can be manufactured so as to have a thin profile and therefore is particularly well-suited for use as a power supply for a flat screen CRT (cathode ray tube). The power supply device includes a voltage regulator, a DC-to-AC converter, and a multiplier. The voltage regulator is connectable to the low-voltage source and is arranged so as to step-down a source voltage level of the low-voltage source to produce an input voltage at a lower voltage level than the source voltage level. The DC-to-AC converter is connected to the input voltage from the voltage regulator and is arranged so as to convert the input voltage into an AC voltage. The multiplier is connected to the AC voltage from the DC-to-AC converter and is arranged so as to convert the AC voltage into a substantially DC output signal having a DC voltage level which is significantly higher than the source voltage level.

Abstract: An AC-to-DC power converter (power supply) with high power factors and which minimizes the input charging current flowing through the separate inductor by locating the separate inductor between a full-bridge rectifier and the transformer but out of the storage capacitor's current path. In this manner, when the input voltage is sufficiently high, the converter draws input current into the transformer through the separate inductor, while current flowing to and charging the storage capacitor is unimpeded by the separate inductor. The current being drawn through the separate inductor and into the transformer may also be used to recharge the storage capacitor. Associated losses are reduced and the separate inductor may be reduced in size.

Abstract: A power supply for supplying power to a load comprises a coupled inductor having a primary winding, at least one secondary winding, and a regulation circuit coupled to the primary winding that allows current or voltage to be supplied to the coupled inductor for a time duration, An error detection circuit is coupled to the secondary winding to compare a voltage or current supplied to the load against at least one threshold. Upon exceeding the threshold, the error detection circuit alters the voltage or current at the secondary winding, which causes a reflected feedback signal to be generated. A reflected feedback regulation circuit coupled to the primary winding provides an information signal to the regulation circuit responsive to the reflected feedback signal. The information signal increases or decreases the time duration to regulate the power supplied to the load.

Abstract: A power source device is so arranged that one of switching elements forming a plurality of power conversion switching circuits which is used in common during each switching cycle is made to have a switching period in which mainly a current is taken up from a power source of first one of the switching circuits, the switching period being varied in a zone in which an input voltage is higher than a predetermined voltage in a cycle of input voltage waveform. Any distortion of input current waveform occurring around lower voltage period of commercial AC source is thereby reduced, in the power source device wherein the power conversion switching circuits employ commonly the switching elements.

Abstract: A method for preparing power factor control integrated circuits which generate linear pulse width modulation (PWM) waveforms is presented. The method of pulse width modulation waveform generation involves providing a capacitor; fast charging the capacitor; and controlling a discharge rate of the capacitor to ensure a constant switching period and a linear PWM waveform. The method is applicable for any single-phase ac/dc converter topology that performs power factor correction. Unlike conventional techniques which utilize three feedback loops, the method of the present invention reduces the total number of feedback loops to two, eliminates input voltage sensing and achieves the same objective. This method results in significant integrated circuit simplification, such as elimination of multiplier, squarer and divider circuits in the control integrated circuit and reduces the cost of the integrated circuit.

Abstract: A multiple output dc to dc converter is described that has multiple regulated output voltages. This is achieved by using a common subcircuit in conjunction with multiple input subcircuits to power multiple output circuits. The common subcircuit is used with an input subcircuit to form a converter input circuit which with a corresponding output circuit produces an output voltage. Any number of input subcircuits can be used with the common subcircuit to produce a corresponding amount of output voltages. The multiple output dc to dc converter described produces output voltage of the same quality as using parallel converters but with a cost and complexity similar to that of using inferior secondary side switches for auxiliary outputs.

Abstract: An auxiliary power transistor which is switched in common with the primary power transistor, and which isolates the voltage-monitoring circuit when the primary power transistor is off. Thus the signal for sensing the secondary current is connected only when the power transistor is turned on, and high voltages in the sensing logic are avoided. This is particularly advantageous for systems where the turn-off times of the power transistor are sought to be synchronized with current zero-crossings. This current-zero-crossing technique may be used to detect zero-crossings of current on a secondary-side switch.

Abstract: A power factor correction circuit includes a boost converter, a zero-current detector for detecting a period in which an inductor current is zero, a half-wave rectifier for supplying a power voltage proportional to an output voltage of the boost converter, a control voltage generator for generating a control voltage to control the turn-on time timing of a sense-FET, a turn-on controller for making constant a turn-on duration of the sense-FET, an over current detector for generating a signal when a mirror terminal current of the sense-FET is greater than a predetermined current, an OR gate for performing a logic OR operation of the output signals of the turn-on controller and the over current detector, an output current controller for generating a gate drive signal of the sense-FET, and an under voltage lock out for turning off the power voltage when the power voltage is less than a predetermined voltage.