Abstract: There are provided an interleaved power factor correction circuit and a power supply device including the same, the power factor correction circuit including: a main switching unit including a first main switch and a second main switch; an auxiliary switching unit including a first auxiliary switch and a second auxiliary switch; an inductor unit positioned between an input power terminal to which the input power is applied and the main switching unit and storing or discharging power according to the switching operations of the main switching unit; and an auxiliary inductor adjusting an amount of current flowing in the auxiliary switching unit when the auxiliary switching unit performs switching operations.

Abstract: A power conversion circuit includes a voltage boost circuit including a boost inductor configured to generate an output voltage in response to an input voltage, and a boost controller configured to control operation of the voltage boost circuit. The boost controller is configured to control operation of the voltage boost circuit in response to a level of current in the boost inductor.

Abstract: A printer includes an energy storage device and a charger for charging the energy storage device and for providing a first DC voltage. The printer includes a first DC-to-DC voltage converter for converting the first DC voltage to a second DC voltage. The printer includes first printer electronics powered by the second DC voltage.

Abstract: Provided is a DC-DC converter with improved power conversion efficiency. A transistor which is incorporated in the DC-DC converter and functions as a switching element for controlling output power includes, in its channel formation region, a semiconductor material having a wide band gap and significantly small off current compared with silicon. The transistor further comprises a back gate electrode, in addition to a general gate electrode, and a back gate control circuit for controlling a potential applied to the back gate electrode in accordance with the output power from the DC-DC converter. The control of the potential applied to the back gate electrode by the back gate control circuit enables the threshold voltage to decrease the on-state resistance when the output power is high and to increase the off-state current when the output power is low.

Abstract: A voltage source converter (10) for use in three-phase high voltage DC power transmission and reactive power compensation. The voltage source converter (10) comprises three converter limbs (12,14,16) connected in a bridge circuit arrangement wherein each of first and second converter limbs (12,14) includes a multilevel converter (18) and a third converter limb (16) includes a capacitor (20) on each side of a series AC phase connection (22). The multilevel converters (18) are controllable to synthesize waveforms at series AC phase connections (24,26) of the first and second converter limbs (12,14).

Abstract: A method for activating a rectifier having active switching elements in the event of a load dump, the active switching elements being activated during the voltage clamping in such a way that the clamp voltage in at least one switching branch complies with a signal form predefined as a function of time within at least one half-period of the current to be rectified.

Abstract: A power source apparatus includes: a first series circuit that has a first rectifier element, a first switching element, and a third rectifier element; a second series circuit that has a second rectifier element, a second switching element, and a fourth rectifier element; a reactor connected between a connecting point of the first rectifier element and the first switching element and a connecting point of the second rectifier element and the second switching element; and a current detection unit having a first resistor element. The first and second switching elements are controllable based on a first zero current detection signal in accordance with a first current detected in the current detection unit, and a desired direct current voltage is fed to a load circuit.

Abstract: An inverter comprising: a circuit including arms connected in parallel, each of the arms including a first switch and a second switch connected in series; and a gate drive circuit configured to control, by pulse-width modulation using synchronous rectification, each of the first switch and the second switch to switch to an on-state or an off-state, wherein each of the first switch and the second switch includes: a channel region that is conductive in both a forward direction and a reverse direction in the on-state, and that is not conductive in the forward direction in the off-state; and a diode region that is combined as one with the channel region, and that is conductive only in the reverse direction, the diode region being unipolar, and the gate drive circuit synchronizes a timing at which the gate drive circuit outputs a signal for causing the first switch to switch to the on-state with a timing at which the gate drive circuit outputs a signal for causing the second switch to switch to the off-state, and

Abstract: An AC to DC converter system is disclosed in which a conversion circuit for converting an AC input signal to a DC output signal is operably coupled with an enabling circuit designed for sensing and output parameter indicative of the presence or absence of a load at the DC output. The system is designed so that the conversion circuit operates in an inactive standby state when there is no load, and in an active state for supplying DC power when a load is present. The enabling circuit is configured to operate using low power.

Abstract: A switching power supply that conducts switching of an input voltage by a switching element to obtain a specified output voltage includes: an ON width controlling component that controls an ON width of the switching element; a zero current detecting component that detects zero current through the switching element to turn ON the switching element; a frequency reducing component that delays a turn ON timing of the switching element upon detection of a light load condition by a load condition detecting component to reduce a switching frequency of the switching element; and an AC period detecting component that detects a period of the input voltage to hold the load condition detected by the load condition detecting component over every period detected by the AC period detecting component.

Abstract: A method of generating an output voltage from a variable input voltage with a power factor correction (PFC) system is disclosed. The PFC system includes a first power rail and a second power rail connected in parallel between an input for receiving the input voltage and an output for outputting the output voltage. The method includes operating one or both of the first power rail and the second power rail to generate the output based, at least in part, on whether the input voltage exceeds a threshold voltage. Power supplies and PFC systems suitable for performing the method are also disclosed.

Abstract: In accordance with an embodiment, a converter includes a power factor controller that varies the switching frequency of a switching transistor in accordance with a signal representative of power at the input of the converter.

Abstract: A power supply controller includes a switching signal generator, a zero crossing detection (ZCD) circuit, first and second logic gates, and an interval generator. The switching signal generator generates a switching signal and the ZCD circuit generates a ZCD signal that pulses each zero-crossing of an ac input voltage. The first logic gate generates a first output when the ZCD signal pulses while the output of the power supply is below a threshold reference. The second logic gate generates a second output when the ZCD signal pulses while the output of the power supply is above the threshold reference. The interval generator is enabled in response to the first output and disabled in response to the second output. The interval generator allows the switching signal to pass through the interval generator to the switch when enabled and does not allow the switching signal to pass when disabled.

Abstract: A bridge-less step-up switching power supply device includes (i) a first and a second reactor having: a first and a second main winding connected to a first and a second input terminal, respectively; and a first and a second auxiliary winding magnetically coupled to the first main winding and connected to the first and second main windings, the first and second auxiliary windings having a first and a second leakage inductance, respectively; (ii) a first and a second diode connected between the first and second auxiliary windings and a first output terminal, respectively; (iii) a first capacitor connected between the first output terminal and a second output terminal; (iv) a second capacitor connected between a connection point of a third switch and a fourth switch, and the first output terminal; and (v) a controller for controlling turning on/off of first to fourth switches.

Abstract: An embodiment of the invention relates to a power converter including an inductor coupled in series with a power switch and a resistor coupled to a winding of the inductor. Input and output power converter voltages including an input brownout condition or an output overvoltage condition are estimated, and the output voltage may be regulated, by sensing a current in the resistor. An input current waveform can thereby be controlled to replicate substantially the input voltage waveform. The controller adjusts an on time and terminates an off time of the power switch by sensing respectively a current and a change of current in the resistor. The controller may sense a current flowing in the resistor to select a line voltage range of the input voltage to the power converter. The controller may estimate an input current to the power converter employing the current flowing in the resistor.

Abstract: A rectifier circuit includes a first alternating current (AC) voltage input terminal, a second AC voltage input terminal, a signal generating circuit, a first energy generating circuit, a second energy generating circuit, a third energy generating circuit, a first output terminal, and a second output terminal The first and second AC voltage input terminals receive an AC voltage. The signal generating circuit generates control signals. The first energy storing circuit is charged by the AC voltage. In a positive period of the AC voltage, the first energy storing circuit discharges to the second energy storing circuit.

Abstract: A rectifier circuit includes a three-phase alternating current (AC) voltage, a first rectifier unit, a second rectifier unit, a third rectifier unit, a first voltage output terminal, a second voltage output terminal, a first energy storing circuit and a second energy storing circuit. The three-phase AC voltage generates a first AC voltage, a second AC voltage, and a third AC voltage, and outputs them to the first rectifier circuit, a second rectifier circuit, and a third rectifier circuit correspondingly. The first energy storing circuit and the second storing circuit are connected in series and are coupled between the first voltage output terminal and the second voltage output terminal, to drive a load. In a positive period of each AC voltage, the second energy storing circuit is charged by each rectifier unit. In a negative period of each AC voltage, the first energy storing circuit is charged by each rectifier unit.

Abstract: In a power conversion apparatus that converts AC power to DC power, an inverter circuit including one or more single-phase inverters connected in series with each other is connected in series at the subsequent stage of a rectification of an AC input. At the subsequent stage of the inverter circuit, a smoothing capacitor connected via a rectification diode, and a short-circuiting switch for bypassing the smoothing capacitor are provided. The short-circuiting switch is subjected to ON/OFF control by PWM control such that a voltage of the DC voltage supply of the inverter circuit follows a target voltage. The inverter circuit is subjected to output control such that a DC voltage of the smoothing capacitor follows a target voltage and an input power factor is improved.

Abstract: A fixed-on-time controller utilizing an adaptive saw signal for discontinuous mode PFC power conversion, the fixed-on-time controller comprising: an error amplifier, having a negative input end coupled to a feedback signal, a positive input end coupled to a reference voltage, and an output end for providing a threshold signal; an adaptive current source generator, used to generate an adaptive current source according to the threshold signal; a capacitor, charged by the adaptive current source, being used for carrying a saw signal; a switch, used to discharge the capacitor under the control of a reset signal; and a comparator, having a negative input end coupled to the threshold signal, a positive input end coupled to the saw signal, and an output end for providing a turn-off signal; and a fixed-on-time driver circuit, used to provide a driving signal and the reset signal according to the turn-off signal and a sensing signal.

Abstract: There is provided an interleaved type power factor correction circuit having a transformer forming a separated winding structure, which is formed by integrating two inductors separately wound around the transformer. The interleaved type power factor correction circuit including a rectifying unit rectifying a commercial alternating current power, a transformer having a first inductor winding and a second inductor winding, a bobbin part, and a core part, a switching unit switching a power transmitted to the first and second inductor windings, a controlling unit controlling a switching operation of the switching unit in order to allow a phase difference between a current and a voltage of the switched power to satisfy a predetermined phase difference, and a stabilizing unit stabilizing the switched power from the switching unit.

Abstract: A method is directed to providing adaptive digital control for the PFC front-end of a switching mode power supply. The method uses an evaluation model to adjust control loop parameters of a control algorithm used by a controller on the primary side of the power supply. The method performs a series of step adjustments of the control loop parameter values to determine optimized values. In some implementations, the method determines and compares the line current THD corresponding to different control loop parameter values. The method provides simplified digital control loop design, optimizes PFC front-end performance, improves system efficiency by decreasing harmonic ripples, and reduces labor cost and time to market due to shorter research and development phase. System performance optimization is fully adaptive adjusted for changes in operating conditions due to, for example, environmental and temperature variations.

Abstract: A circuit switching element is provided that switches a step-up/step-down bidirectional chopper circuit, arranged between a DC bus and a power storage element, to a first chopper circuit or to a second chopper circuit, whose step-up and step-down characteristics are in a complementary relation. The first and second chopper circuits are used together at a time of charge and discharge. Accordingly, an AC motor drive device having mounted therein a power storage system is obtained, in which the power storage system can perform charge and discharge to and from the power storage element, regardless of a bus voltage and can increase energy use efficiency.

Abstract: A power supply circuit includes a rectifier, a charging circuit, and a storage capacitor. An AC signal is rectified by the rectifier thereby generating a rectified signal VR between a VR node and a GND node. The capacitor is coupled between an output voltage VO node and the GND node. If VR is greater than a first predetermined voltage VP then the VO node is decoupled from the VR node. If VR is below VP then the charging circuit supplies a substantially constant charging current from the VR node, through the charging circuit, to the VO node, and to the capacitor, provided that VO on the capacitor is below a second predetermined voltage VO(MAX) and provided that VR is adequately high with respect to VO. Due to the charging current, the voltage VO on the storage capacitor is restored to the desired second predetermined voltage.

Abstract: There is disclosed an AC/DC converter circuit. The circuit comprises: an input terminal for receiving an AC supply voltage; a driver circuit adapted to supply a DC drive current or voltage to an output of the circuit based on a signal provided to a control terminal of the driver circuit; and an AC coupling network connected between the input terminal and the control terminal of the driver circuit. The AC coupling network is adapted to derive a signal from an AC supply voltage received by the input terminal and to supply the derived signal to the control terminal of the driver circuit.

Abstract: The present invention relates to a switch controller, a power supply including the same, and a method for driving the same. An AC input of the power supply is connected to a rectification circuit. The power supply includes a power switch to which an input current passed through the rectification circuit flows during an on-period and a switch controller, the switch controller detects a half-on time point that is the intermediate time point of the on-period, detects a sense voltage that is determined by a current flowing to the power switch during the on-period at the half-on time point, generates a modulation wave by controlling a reference wave according to the detected voltage, and controls switching operation of the power switch according to the modulation wave.

Abstract: A method of controlling a brushless motor that includes rectifying an alternating voltage to provide a rectified voltage, and exciting a winding of the motor with the rectified voltage. The winding is excited in advance of predetermined rotor positions by an advance period and is excited for a conduction period over each electrical half-cycle of the motor. The length the advance period and/or the conduction period is defined by a waveform that varies periodically with time. The method then includes adjusting the phase of the waveform relative to the alternating voltage in response to a change in one of motor speed and RMS value of the alternating voltage. Additionally, a control system that implements the method, and a motor system that incorporates the control system.

Abstract: A Power Factor Corrector (PFC), typically used as the first stage of switched mode power supplies, particularly suited for Universal Mains inputs, is disclosed, along with methods for controlling a switched mode power supply having power factor correction. In order to increase efficiency, particularly under low load conditions, without undue degradation of the Power Factor, the switching of the PFC circuit is confined to one or more operating windows within each half-cycle. In example embodiments, the operating window comprises a small time window centered around the peak of the mains voltage. The higher the power level, the wider the switching window.

Abstract: The present invention relates to a switching operation control device of a power switch, an LED light emitting device including the same, and a control method thereof. The control device detects a zero crossing time when a voltage at an input end of the power switch becomes a zero voltage, generates a reference signal that is synchronized with the voltage at the input end of the power switch by using the detected zero crossing time, and compensates the generated reference signal with a first voltage that is greater than the zero voltage during a blocking period corresponding to the zero crossing time.

Abstract: An AC to DC converter for converting an AC input voltage to a regulated DC output voltage using a Z-type converter and rectified switches. The Z-type converter includes first and second inductors, a capacitor, two rectified switches and a load device coupled in a cross-coupled configuration. The Z-type converter may be configured according to a Z-source or a quasi-Z-source rectifier network. The AC input voltage is applied to an input and the DC output voltage is developed across the load device. Each rectified switch may be configured as a series-coupled diode and electronic switch or as a dual gate GaN device with a shorted gate. A control network monitors the DC output voltage and develops a control signal for controlling the first and second rectified switches to regulate the DC output voltage. The control network may control the rectified switches based on duty cycle control or current mode control.

Abstract: An integrated circuit (IC) comprises a rectifier/regulator circuit coupled to receive an ac source voltage and output a regulated dc voltage. The rectifier/regulator circuit includes first and second switching elements that provide charging current when enabled. The first and second switching elements do not provide charging current when disabled. A sensor circuit is coupled to sense the regulated dc voltage and generate a feedback control signal coupled to the rectifier/regulator circuit that enables the first and second switching elements when the regulated dc voltage is above a target voltage, and disables the first and second switching elements when the regulated dc voltage is below the target voltage.

Abstract: The present invention provides a current detection circuit, a controlling circuit using the current detection circuit and a power conversion circuit using the controlling circuit, the current detection circuit comprises a sample keeping circuit, a rising edge detection circuit, a falling edge detection circuit, a sequential controlling circuit, a synchronous detection circuit and a lowpass filter. The inventive current detection circuit for the power conversion circuit obtains signals of the output current by detecting loop current of the master switch and processing the loop current.

Abstract: In a switching power supply apparatus, an alternating-current input power supply is input to the input terminals of a power factor correction converter and a DC-DC converter is connected to output terminals. A load is connected to the output of the DC-DC converter. A digital signal processing circuit takes the product of an output voltage error and a detection value of the input voltage as a current reference amplitude value and controls the on period of a switching element in accordance with the difference between the current reference amplitude value and the current flowing through an inductor. The target value of the output voltage or the output voltage error is corrected using a value that is proportional to the current reference amplitude value such that the output voltage rises as the load goes from a light to a heavy load state.

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: The present invention pertains to an inductor current detection circuit in a switching mode power supply, and a light-emitting diode (LED) driver thereof. In one embodiment, an inductor current detection circuit configured in a switching mode power supply under discontinuous conduction mode, can include: (i) a voltage detection circuit configured to generate a sampling voltage based on a drain-source voltage of a power switch in the switching mode power supply; (ii) a voltage holding circuit configured to receive the sampling voltage, and to generate a holding voltage through a sampling and holding operation; and (iii) a comparison circuit configured to compare the sampling voltage against the holding voltage, and to generate a zero-crossing signal when the sampling voltage is less than the holding voltage, where the zero-crossing signal is configured to represent an inductor current ending time of the switching mode power supply.

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 boost converter capable of reducing a common-mode current that flows to the outside of a casing. In the converter, a boost circuit includes first and second inductors and at least one switching element electrically connected therebetween. A controller turns on and off the at least one switching element to boost an input voltage of the boost circuit. A first floating capacitor is formed between a first electrical path, which is at the same potential as a junction between the at least one switching element and the first inductor, and a mounting member coupled to a reference potential member with an insulator therebetween. A second floating capacitor is formed between a second electrical path, which is at the same potential as a junction between the at least one switching element and the second inductor, and the mounting member.

Abstract: A transistor active bridge circuit (100) including first and second field-effect transistors (102, 104) of a first channel type, and third and fourth field-effect transistors (106, 108) of a second channel type that is different from the first channel type. The transistor active bridge circuit also includes a plurality of gate drive circuits for the field-effect transistors. A set of voltage dividers (110/112, 114/116, 118/120, 122/124) and/or voltage clamping devices (126, 128, 130, 132) permit the circuit (100) to efficiently operate over a wider range of input voltages, without potential damage to the gate drive circuits.

Abstract: A power factor correction stage comprising: an input terminal configured to receive an input signal; an output terminal configured to provide an output signal; a first converter stage and one or more further converter stages, wherein each of the converter stages is connected to the input terminal and the output terminal, and each converter stage comprises a switch; and a controller configured to operate the switches of the converter stages. The controller is configured to operate the switch of the one or more further converter stages at a period of time after operation of the switch of the first converter stage for a current switching cycle, wherein the period of time corresponds to a proportion of the switching frequency for an earlier switching cycle that does not correspond to substantially the period of the earlier switching cycle divided by the number of converter stages.

Abstract: A method of controlling a single-phase voltage source AC/DC converting circuit has internal equivalent impedance as seen from an AC terminal, for converting power from a DC voltage source connected to a DC terminal to single-phase AC power or for converting single-phase AC power from a single-phase AC source connected to the AC terminal to DC power in accordance with a pulse width of a gate signal generated based on a PWM command.

Abstract: An example controller for use in a power supply includes a zero crossing detection (ZCD) circuit, a threshold detection circuit, and a punctuated switching control circuit. The ZCD circuit generates a ZCD signal that pulses each zero-crossing of an ac input voltage. The threshold detection circuit receives and compares an output of the power supply with a threshold reference. The punctuated switching control circuit generates a switching signal to control a switch to regulate the output of the power supply. The switching signal is generated to have intervals of switching and intervals of no switching, where each interval of switching begins responsive to the output of the power supply dropping below the threshold reference and each interval of no switching begins responsive to the output rising above the threshold reference. Each interval has a beginning that is synchronized with a pulse of the ZCD signal.

Abstract: A flyback converter includes input terminals and output terminals. A transformer with a first winding and a second winding are inductively coupled. A first switching element is connected in series with the first winding and a first series circuit with the first switching element, the first winding being coupled between the input terminals. A rectifier arrangement is connected in series with the second winding and a second series circuit with the rectifier arrangement, the second winding being coupled between the output terminals. The rectifier arrangement includes a second switching element. A control circuit is configured in one drive cycle to switch on the first switching element for a first time period. After the first time period the second switching element is switched on for a second time period. A third time period is determined between an end of the second time period and the time at which the transformer assumes a predetermined transformer state.

Abstract: Consistent with an example embodiment, there is a control method which reduces the steps: instead of a constant on-time for the switch, the duration of the on-time is increased each time an additional valley to be skipped. The predetermined increase may be either a fixed fractional increase or a further additional increment; it may be determined by a small regulation loop that multiplies the on-time from the main loop with a factor equal to the ratio between measured period time and the sum of primary and secondary stroke times.

Abstract: An exemplary direct current (DC) voltage generating apparatus for generating stable DC voltages includes a voltage conversion circuit, a voltage control circuit, and a voltage regulating circuit. The voltage conversion circuit receives an alternating current (AC) voltage, and converts the AC voltage to a first DC voltage. The voltage control circuit receives the first DC voltage, and converts the first DC voltage to a second DC voltage and a control signal. The voltage regulating circuit receives the control signal, and regulates the second DC voltage to a stable second DC voltage at the voltage control circuit according to the control signal.

Abstract: The present invention relates to a switch controller, a power supply including the same, and a driving method thereof. An AC input of the power supply is connected to a rectification circuit. The power supply includes a power switch to which the AC input passed through the rectification circuit flows during a turn-on period of the power switch and a switch controller detecting a half-on time point that is an intermediate time point of the turn-on period, calculating the AC current using a result of sampling a sense voltage that depends on a current flowing to the power switch during the turn-on period at the half-on time point and the turn-on period, and controlling the input current to have a reference sine wave. The reference sine wave has a sine wave that is full-wave rectified from the AC input.

Abstract: A dimming power supply includes a power source, a transformer, a full bridge rectifier and a control switch.

Abstract: A three phase rectifier rectifies received three phase a.c. power to generate a ripple d.e. voltage. A power distribution bus conveys distribution power comprising the ripple d.c. voltage or an a.c. voltage derived therefrom to a location of an LED based lamp that is distal from the three phase rectifier. Additional circuitry disposed with the LED based lamp drives the LED based lamp using the distribution power.

Abstract: In some aspects of the invention, a zero current detecting circuit of a switching power supply device detects a gradient of the current flowing in an inductor in the OFF state of the switching element and detects the timing at which the current through the inductor becomes zero corresponding to the detected gradient of the inductor current. Specifically, the zero current detecting circuit receives a signal for controlling ON/OFF driving of the switching element and a voltage signal proportional to the current flowing through the inductor in an OFF state of the switching element. The voltage signal can be compared sequentially with first and second comparison reference voltages to control charging and discharging of a capacitor. Further, the zero current detecting circuit can detect a timing at which the charging and discharging voltage of the capacitor as the timing of zero current flowing through the inductor.

Abstract: Provided is a power factor correction circuit capable of reducing ringing sound of a transformer produced when an overshoot protection is effected. An output voltage control circuit performs constant voltage-control such that capacitor charge voltage of an output capacitor corresponds to a first voltage value, and when the capacitor charge voltage of the output capacitor reaches a second voltage value higher than the first voltage value, an overvoltage detecting unit detects the second voltage value. Further, a current limiting unit detects a value of a switching current through a switching element, and determines a limiting value of the level of the switching current. Then, the switching current is limited to the limiting value, and when an overvoltage detecting unit detects the second voltage value, a limiting value changing unit causes the current limiting unit to change the limiting value to decrease the value of the switching current.

Abstract: According to one embodiment, a power supply circuit includes an input terminal, a rectifier circuit, a power factor improvement circuit, a DC/DC converter, and a control module. The DC/DC converter converts the level of a DC voltage output from the power factor improvement circuit. The control module determines on the basis of the output voltage of the rectifier circuit whether an input power supply supplied to the input terminal is AC or DC. The control module generates a DC power supply by use of the power factor improvement circuit and DC/DC converter when the input power supply is AC and generates a DC power supply by controlling the operation of the power factor improvement circuit and DC/DC converter according to the voltage of input DC power supply when the input power supply is DC.

Abstract: Aspects of the invention provide an error amplifier that can compare a feedback voltage of an output voltage with a reference voltage to produce a resulting error signal in cooperation with a phase compensating circuit. In some aspects of the invention, an AC detecting circuit makes a decision as to whether a detected input voltage signal is that of a 100 Vac system or that of a 200 Vac system to change the gain of the error amplifier according to the result of the decision. When the voltage signal Vis is lower than the threshold voltage established beforehand, for making the transient response speed of the phase compensating circuit faster, the AC detecting circuit increases the gain of the error amplifier. When the voltage signal is higher than the threshold voltage established beforehand, for making a power factor higher, the AC detecting circuit decreases the gain of the error amplifier.