A power amplifier includes: first and second bias terminals to which bias voltages are respectively supplied; a first transistor having a first control terminal connected to the first bias terminal, a first terminal that is grounded, and a second terminal; a second transistor having a second control terminal connected to the second bias terminal, a third terminal connected to the second terminal, and a fourth terminal; a capacitor connected between the second control terminal and a grounding point; and a variable resistor connected in series with the capacitor, between the second control terminal and the grounding point.

Systems and methods are provided for generating an amplitude modulation signal to a switchmode power amplifier. A DC to DC switch is configured to receive a DC input voltage and to provide a DC output voltage. A low dropout regulator is configured to provide the amplitude modulation signal according to a modulation control signal received by the low dropout regulator. A control circuit is configured to establish a nominal operating power level for the power amplifier via the amplitude modulation signal and to maintain a minimum voltage difference between the DC output voltage and the low dropout regulator output. A modulator control circuit is configured to provide the modulation control signal to the low dropout regulator. The modulator control circuit provides the transition from a high amplitude to a low amplitude and a transition from the low amplitude to the high amplitude at configurable first and second slopes, respectively.

An apparatus for amplifying power is provided. The apparatus includes a supply modulator for generating a supply voltage based on an amplitude component of a transmission signal, and a power amplify module for amplifying power of the transmission signal using the supply voltage, wherein the power amplify module includes a first power amplifier and a second power amplifier, and when an output power of the transmission signal is greater than a reference power, the first power amplifier amplifies the power of the transmission signal using the supply voltage, and when the output power of the transmission signal is equal to or less than the reference power, the second power amplifier amplifies the power of the transmission signal using the supply voltage.

An automatic gain control device includes: a variable gain adjusting unit, for adjusting an input signal by a variable gain and outputting an adjustment result; an analog-digital converting unit, for performing analog-digital conversion on the adjustment result to obtain an analog-digital conversion result; and a gain determining unit, for determining a distribution status over a predetermined period of time of a maximum or a minimum of the analog-digital conversion result, comparing the distribution status with a first distribution condition, and if the distribution status meets the first distribution condition, then keeping the variable gain unchanged, otherwise changing the variable gain and determining newly a distribution status until the newly determined distribution status meets a second distribution condition which is at least as strict as the first distribution condition.

An accessory for coupling to an attachment mechanism of an oscillating power tool includes a working end, an opposite rear end, and a fitment portion adjacent the rear end portion. The fitment portion includes a generally U-shaped opening having a central portion and a rearward portion open to the rear end, and configured to receive a post of a tool clamping mechanism. The fitment portion further includes a first plurality of openings in communication with and extending radially outward from the central portion, a second plurality of openings not in communication with and positioned radially outward from the central portion. The central portion, the first plurality of openings, and the second plurality of openings are configured to couple the fitment portion to a plurality of different configurations of attachment mechanisms for oscillating power tools.

Embodiments of the present invention generally provide chamber components with enhanced thermal properties and methods of enhancing thermal properties of chamber components including bonding materials. One embodiment of the present invention provides a method for fabricating a composite structure. The method includes applying a bonding material to a first component, and converting the bonding material applied to the first component to an enhanced bonding layer by heating the bonding material to outgas volatile species from the bonding material. The outgassed volatile species accumulates to at least 0.05% in mass of the bonding material. The method further includes contacting a second component and the enhanced bonding layer to join the first and second components.

A fastener holder includes a driving tool stem having a number of orifices, a driving tool shank engaged in the stem for engaging with a tool element and having a number of depressions formed in the shank, a number of bearing members engaged in the orifices of the stem for engaging with the depressions of the shank and for selectively anchoring the shank to the stem, and a barrel includes a relatively smaller segment for selectively engaging with the bearing members and for forcing the bearing members to engage into the depressions of the shank and to anchor and lock the driving shank to the stem and for allowing the driving shank and the tool element to be selectively rotated and driven by the stem.

A power tool has a driving shaft driving a working element, a fastening piece fastening the working element to the driving shaft having a projecting shaft insertable into the driving shaft, a locking assembly locking the projecting shaft in the driving shaft having a locking member wherein the locking member has a locking position for locking the projecting shaft with the driving shaft and a loosening position for loosening the projecting shaft with the driving shaft. At the locking position, the fastening piece is pressed towards an end portion of the driving shaft by an elastic component. The locking assembly further includes a movable member arranged outside of the driving shaft, the movable member having a first portion and a second portion which can be directly or indirectly mated with the locking member wherein a radial distance of the first portion relative to a shaft center of the driving shaft is unequal to that of the second portion relative to the shaft center of the driving shaft.

A device for forming containers from heated parisons of thermoplastic material, which includes a heating section and a blow molding unit provided with at least one blow molding station. The parisons are held along at least a portion of a transport path between the heating section and the blow molding unit by a carrying element, which has a head that can be inserted into a mouth section of a parison and which includes at least two positionable clamping elements. At least one of the clamping elements is positioned in a recess provided on a side of the head relative to a longitudinal axis of the carrying element. The recess has upper and lower sliding surfaces that extend obliquely relative to the longitudinal axis for acting on the clamping element. The upper head part and the lower head part are braced relative to each other by at least one spring.

A liquid flow rate control valve is provided in which since a total area of overlapping sections of a communication hole group (38c, 38d) of a distributor (38) and an outlet opening (37a, 37b) of a sleeve (37) changes when the distributor (38) is rotated by a first electric motor (46), if a rotor (42) is rotated by means of a second electric motor (47), an input port (31e) communicates with an output port (31f) through an inlet opening (42c, 42d) of the rotor (42), the communication hole group (38c, 38d) of the distributor (38), and the outlet opening (37a, 37b) of the sleeve (37) when the inlet opening (42c, 42d) of the rotor (42) passes through the overlapping sections, thereby making it possible to carry out PWM control of a flow rate of liquid. Since a thrust load in an axis (L) direction does not act on the distributor (38) and the rotor (42), supporting the distributor (38) and the rotor (42) becomes easy, thereby enabling the cost and weight to be cut.

In a stroke-limiter equipped integral power steering apparatus, a valve body of a spring-loaded-plunger-equipped limiter valve is configured to enable a position of the valve body relative to a housing to be adjusted in a longitudinal direction of the valve body via an intermediate sleeve.

An arrangement for providing a throttle cross-section for a fluid flow. The throttle cross-section can be varied depending on a pressure difference present across the throttle cross-section. The arrangement is designed such that the polarity of the pressure difference, by which the throttle cross-section can be varied and/or changed. It is thereby possible to use the arrangement for fluid flows that alternate in the flow direction thereof.

A geared motor actuator having a simplified mechanical structure for driving a closing part, such as a vehicle window, moved as far as at least one end position by an electric motor (MO) via a gear (G), preferably a worm gear. Shortly before the end position is reached, switch-off of the electric motor (MO) is performed in accordance with a control device (ST). The gear (G) is drive-connected to an output driver of the closing part without any damping means. The worm wheel (4) of the worm gear, being a solid, integral component that is preferably injection-molded from plastic, is preferably designed to include the output driver as part of the integral component, and provided with a drive pinion (4.1).

A method and a system for supplying power to a microcontroller with a single cell. One embodiment of the present invention discloses incorporation of a power supply pump circuit with the microcontroller and their dynamic interaction. The microcontroller sends its power requirements to the power supply pump circuit and in response, the power supply pump circuit controls the operating voltage with optimal efficiency. The dynamic update of power supply pump circuit results in an efficient use of the power supply pump circuit and thus results in a reduction of the number of dry cell batteries to only a single cell. Incorporation of the microcontroller and power supply pump circuit onto a single chip reduces the pin number requirements as well as the space required on the printed circuit board.

An information handling system (IHS) employs a power fault protection circuit to protect the IHS from overvoltages which may occur on an information line from a power adapter to the IHS. The system includes a processor coupled to the protection circuit. The circuit is operative in a first mode to decouple an information line from the IHS in response to a disable command and operative in a second mode to decouple the information line from the IHS when a voltage in the information line exceeds a predetermined threshold voltage.

A power tool has an electric motor that includes a commutator, with which at least one commutator brush is acted upon with spring force via at least one commutator spring in the direction of a non-rotatable collector of the commutator. At least one auxiliary tool for adjusting the commutator spring is located on a component of the power tool.

A method and a system for supplying power to a microcontroller with a single cell. One embodiment of the present invention discloses incorporation of a power supply pump circuit with the microcontroller and their dynamic interaction. The microcontroller sends its power requirements to the power supply pump circuit and in response, the power supply pump circuit controls the operating voltage with optimal efficiency. The dynamic update of power supply pump circuit results in an efficient use of the power supply pump circuit and thus results in a reduction of the number of dry cell batteries to only a single cell. Incorporation of the microcontroller and power supply pump circuit onto a single chip reduces the pin number requirements as well as the space required on the printed circuit board.

Apparatuses, methods and systems for lighting fixture determining its power usage and monitoring its operational health are disclosed. One embodiment includes a method of a lighting fixture determining its power usage. The method includes sensing, by an ambient light sensor, an intensity of light emitted from the lighting fixture, and estimating power usage of the lighting fixture based on the sensed intensity of light.

The invention relates to a combination cylinder, including a service brake cylinder as an active service brake with at least one service brake piston actuated by a pressure medium, the piston actuating a brake mechanism via a service brake piston rod, and further including a spring-loaded brake cylinder as a passive parking brake with a spring-loaded brake piston actuated by a pressure medium against the action of at least one pre-loaded spring, wherein the spring-loaded brake piston in the event of the parking brake is actuated transmits the power of the at least one pre-loaded spring by means of a power-transmitting transmission to the service brake piston rod. According to the invention, the transmission is designed such that the movements of the spring-loaded brake piston and the service brake piston rod are coaxial and the power transmission increases with increasing stroke of the spring-loaded brake piston.

A rodless power cylinder includes a cylinder body, a piston assembly adapted to reciprocate in the cylinder body, a magnet mounted at each of the two ends of the piston assembly, a valve mounted at each of the two ends of the cylinder body for guiding a flow of air or fluid in and out of the cylinder body to cause the piston assembly to reciprocate, a magnetic sensor mounted in a sensor mounting groove at each of the two valves for sensing the position of the respective magnet, a movable member mounted around the cylinder body and coupled to the piston assembly by a magnetic force for synchronous reciprocating motion.

Cam follower roller device, notably for an internal combustion engine fuel injection pump, comprising a tappet (12) and a roller (14) mounted to rotate on the tappet and intended to press against a cam. The tappet (12) comprises a roller support body (16), a shaft (26) for mounting the roller on the said body, and a guide sleeve (18) attached to the support body and at least partially surrounding the said body. The ends of the shaft are fixed in through-holes in the support body.

A deployable pedestrian protection lower leg stiffen apparatus includes a left and a right linear actuator mountable adjacent to respective left and right forward frame members of a vehicle and a lower leg stiffener attached to and movable by the actuators. The actuators are extendable along respective deployment axes extending forward and downward relative to the vehicle to move the stiffener between a retracted position rearward of a forward surface of a front bumper beam and above a ground clearance plane and a deployed position forward of the retracted position and below the ground clearance plane. The actuators have rotational joints defining a horizontal pivot axis about which at least the forward portions of the piston may rotate upward along with the stiffener to prevent damage to the system if it strikes a road obstacle.

An airflow control device is mounted to the front end of an automotive vehicle and includes an upper air scoop section having a scoop channel disposed rearward of a bumper assembly and oriented to direct airflow entering a bumper intake opening toward an air-receiving powertrain component. A lower air dam section extends downwardly from the upper section to be positioned below a lower extent of the bumper assembly to deflect airflow away from an underside of the vehicle.

A method for casting a thrower for a railcar coupler includes creating a mold box that is vertically parted in halves, each half defining a side of a thrower cavity and that includes at least a portion of a sprue at a location above the thrower cavity, the thrower cavity also being oriented vertically; pouring molten metal into the mold box through the sprue and into the thrower cavity while the mold is oriented vertically; and shaking out the mold box to release the thrower after the thrower has cooled. Creating the mold box may be executed through a cold shell process. The halves of the mold box may include reflective images of the sides of two thrower cavities and an ingate connected between the sprue and one of the two thrower cavities.

A paper shredder with an allowable thickness warning function is provided. The paper shredder includes a casing and an upper cover. An input tray is disposed on the casing for placing plural papers thereon. A pressing member and a thickness detecting device are installed on the upper cover. When the pressing member is contacted with the plural papers on the input tray and pushed by the plural papers, the pressing member is moved. The thickness detecting device is located near the pressing member. Moreover, in response to the movement of the pressing member, the thickness detecting device may be triggered. If an overall thickness of the plural papers exceeds an allowable thickness, the pressing member is pushed by the plural papers. Consequently, the thickness detecting device is triggered by the pressing member to generate a warning signal.

A machine for distributing blowing wool from a bag of compressed blowing wool is provided. The machine includes a chute having an inlet end configured to receive the bag of compressed blowing wool. A shredding chamber is positioned downstream from the chute and configured to shred and pick apart the blowing wool. The shredding chamber includes a plurality of shredders configured for rotation. Each shredder includes a plurality of paddle assemblies mounted to a shredder shaft. Each paddle assembly has a plurality of paddles. The paddles have a hardness within the range of 60 A to 70 A Durometer to better grip the blowing wool for shredding and prevent jamming of the blowing wool within the shredder.

Disclosed is a pressurized hollow fiber membrane module that exhibits improved durability without deterioration in packing density and permeation flux. The pressurized hollow fiber membrane module includes a composite hollow fiber membrane comprising a tubular braid woven by yarns and a polymer film on the outer surface of the tubular braid. At least one of the yarns comprises a small-fineness filament and a medium-fineness filament. The small-fineness filament comprises first monofilaments having a fineness of 0.01 to 0.4 denier, the medium-fineness filament comprises second monofilaments having a fineness higher than 0.4 and lower than 3, and a ratio of thickness of the tubular braid to outer diameter thereof is 15 to 35%.

A device for filtering liquids has a container, units for introducing a liquid to be filtered into the container, a container outlet for unfiltered liquid to be discharged from the container, and at least one rotor, which is drivable to rotate around the container axis. The rotor has a hollow shaft mounted in an end wall and a support device fastened thereon for filter elements, which are arranged with a clearance to the container axis or rotate around their own axis. The interior of the filter elements opens via the support device and the hollow shaft out of the container as the discharge for filtered liquid. To provide improved filtration conditions, the container internal radius of the inner wall of the container circumferential shell is enlarged up to a maximum in the container circumferential direction while bulging the inner wall between two minima. The bulge forms a guide unit which guides the liquid toward the filter elements.

An apparatus for treating a flow of fluid with microwave radiation, the apparatus comprising: a vessel having a sidewall and opposed first and second end walls defining a substantially cylindrical chamber, the first end wall being disposed a predetermined distance d1 from the second end wall; a pipeline for flowing fluid through, the pipeline passing through the first end wall towards the second end wall of the vessel, the chamber and the pipeline being substantially co-axial and the pipeline being substantially transparent to microwave radiation; and a microwave radiation inlet in the side wall of the vessel for admitting microwave radiation of wavelength λ into the chamber, wherein the distance d1 is substantially equal to an integral multiple of λ/2 so that the chamber is a microwave resonator.

A reusable aseptic connector is provided. The connector may be used to provide fluid communication between a bag-in-box (BIB) container and a beverage dispenser. The connector may provide aseptic properties of the connection by insulation of an inner volume of a first part and an inner volume of a second part, with the beverage component kept from contacting any of the part of the connector structure that are exposed to the environment and have a risk of induced contamination. The connector may comprise a resilient membrane and a sliding tube wherein the sliding tube is configured to have a portion move toward and through the resilient membrane to establish fluid communication between the first part and the second part, and for the portion to move away from the resilient membrane to destablish fluid communication between the first part and the second part when desired.

An apparatus to introduce a defined amount of a second powder into a process container in which a first powder or a powder mixture is present, includes a coupling flange having a cover flap located on the process container. The second powder is introduced into a tubular cartridge mounted displaceably in a transport unit, the latter including a joining flange having a cover flap. The joining flange is joinable to the coupling flange so that the respective cover flaps can be opened, and the cartridge can be pushed through openings thereby provided into the plane of the inner wall of the process container. The second powder is emptied from the cartridge into the process container by a delivery piston. The cartridge may include a piston rod having multiple pistons. Other embodiments include a double piston, a rotatable cartridge core or a rotary closure.

A conveying device for free-flowing fine-particle solids, in particular for powdery and/or granular (mixed) material, especially plastic granulate, includes a vertically arranged and flexibly mountable telescopic pipe for the conveyance of, preferably, polymer granulates, for example in a plant for the filling of polymer granulates.

A powder refilling device includes a refill powder chamber to accommodate a powder bag containing powder, an opener to open the powder bag inside the refill powder chamber, and a squeezer to squeeze the opened powder bag to discharge powder therefrom and reduce a volume of the opened powder bag.

The phase margin compensation method according to an exemplary embodiment of the present invention includes: outputting reference voltage (Vout2); outputting a first reference voltage (Vout1) actually supplied to the target circuit; comparing the reference voltage (Vout2) with the first reference voltage (Vout1) by the comparator; counting any section of an output signal (pulse signal) from the comparator by a predetermined frequency by the duty cycle calculator; and controlling a phase margin of a frequency of output voltage supplied to the target circuit by controlling buffer current based on the duty cycle ratios and the output bit information fed back from the duty cycle calculator.

A DC-DC converter includes a first amplifier that amplifies a first difference between a first reference voltage and a feedback voltage corresponding to an output voltage, a second amplifier that amplifies a second difference between the first reference voltage and an integrated value of the feedback voltage, and a controller that controls a switching circuit to change the output voltage when the first difference reaches the second different.

A method of operating a switching power converter may include determining an average value of a measured parameter for substantially each switching cycle, and adjusting a control parameter during substantially each switching cycle in response to a corresponding one of the average values. In one embodiment, the control parameter comprises a switch duty cycle, and the measured parameter comprises an output current. Determining the average value of the measured parameter may include obtaining a first sample of the measured parameter during a switching cycle, and calculating the average value of the measured parameter during the switching cycle in response to the first sample.

A power supply for a load control device generates a DC voltage and provides an asymmetrical output current, while drawing a substantially symmetrical input current. The power supply comprises a controllably conductive switching circuit for controllably charging an energy storage capacitor across which the DC voltage is produced. The energy storage capacitor begins charging at the beginning of a half-cycle and stops charging after a charging time in response to the magnitude of the DC voltage and the amount of time that the energy storage capacitor has been charging during the present half-cycle. The charging time is maintained substantially constant from one half-cycle to the next. The power supply is particularly beneficial for preventing asymmetrical current from flowing in a multiple location load control system having a master load control device supplying power to a plurality of remote load control devices all located on either the line-side or the load-side of the system.

Circuits and processes for detecting a peak value of an input signal are disclosed. In one example, a peak detector circuit may sample a line sense signal, determine the peak value of the line sense signal during a search window, and output a peak detection signal representative of the determined peak value. In a first mode, the peak detector circuit may cause the peak detection signal to be representative of the determined peak value from an immediately preceding search window. In a second mode, the peak detector circuit may cause the peak detection signal to follow the sampled line sense signal. The peak detector circuit may operate in the second mode in response to the sample of the line sense signal being greater than a peak value of the line sense signal from an immediately preceding search window by more than a threshold amount.

A power conversion system has a power converter configured to receive an input voltage signal, convert the input voltage to an output voltage signal, and provide the output voltage signal to a load and a closed loop compensator configured to receive the output voltage signal and a reference voltage signal, the closed loop compensator configured to transmit an error signal indicative of a difference between the output voltage signal and the reference voltage signal. The power conversion system further has a pulse with modulator configured to receive the error signal and modulate a control signal with the error signal to control the output voltage signal, the pulse width modulator configured to transmit the control signal to the power converter and logic configured to receive the error signal and control the closed loop compensator based upon the error signal. A controller observes the error signal characterstics such as peak-to-peak values, frequency and phase and adjust the closed loop controller variables and other power converter system variables in order to improve the dynamic performance and improve stability.

A method for controlling voltage crossing a power switch of a switched-mode power converter includes the steps of: controlling a switch frequency of the power switch of the switched-mode power converter to a first frequency as activating the switched-mode power converter; and then changing the switch frequency of the power switch to a second frequency after the switched-mode power converter is activated for a predetermined time; wherein the first frequency is lower than the second frequency.

In some aspects of the invention, overcurrent protection is carried out by suppressing fluctuations in current flowing through a switching element after overcurrent detection. A peak current reaching time detection circuit detects a peak current reaching time needed until current flowing through a switching element reaches a peak value. A difference voltage detection circuit, including a ½ time detection circuit which detects a time of ½ an ON time of the preceding cycle of the switching element, detects difference voltage between reference voltage used when detecting overcurrent flowing to a load and a signal which has detected current flowing through the switching element for the ½ time. A delay time adjustment circuit, based on at least one of the peak current reaching time and difference voltage, carries out adjustment and control of a delay time occurring until the time when the switching element is turned off after detecting the overcurrent.

Methods and systems are described for providing power factor correction for high-power loads using two interleaved power factor correction stages. Each power factor correction stage includes a controllable switch that is operated to control the phasing of each power factor correction stage. The phasing of output current from the second power factor correction stage is shifted 180 degree relative to the output current from the first power factor correction stage.

In one implementation, a modular power converter having a reduced switching loss includes a package, a field-effect transistor (FET) including a gate terminal, a drain terminal, and a source terminal, and fabricated on a semiconductor die situated inside the package, and a driver circuit inside the package. The driver circuit is configured to drive the gate terminal of the FET. The driver circuit is further configured to sample a drain-to-source voltage (VDS) of the FET directly from the drain terminal and the source terminal, thereby enabling the reduced switching loss.

A ballast circuit for a Light Emitting Diode (LED) has a regulator element coupled to the LED and to an input voltage source. A control circuit is coupled to the LED and to an input voltage source. A first switching device is coupled in series with the regulator element. A second switching device is coupled to the input voltage and the control circuit.

A “windowless” H-bridge buck-boost switching converter includes a regulation circuit with an error amplifier which produces a ‘comp’ signal, a comparison circuit which compares ‘comp’ with a ‘ramp’ signal, and logic circuitry which receives the comparison circuit output and a mode control signal indicating whether the converter is to operate in buck mode or boost mode and operates the primary or secondary switching elements to produce the desired output voltage in buck or boost mode, respectively. A ‘ramp’ signal generation circuit operates to shift the ‘ramp’ signal up by a voltage Vslp(p−p)+Vhys when transitioning from buck to boost mode, and to shift ‘ramp’ back down by Vslp(p−p)+Vhys when transitioning from boost to buck mode, thereby enabling the converter to operate in buck mode or boost mode only, with no need for an intermediate buck-boost region.

This disclosure relates to radio frequency (RF) power converters and methods of operating the same. In one embodiment, an RF power converter includes an RF switching converter, a low-drop out (LDO) regulation circuit, and an RF filter. The RF filter is coupled to receive a pulsed output voltage from the RF switching converter and a supply voltage from the LDO regulation circuit. The RF filter is operable to alternate between a first RF filter topology and a second RF filter topology. In the first RF filter topology, the RF filter is configured to convert the pulsed output voltage from a switching circuit into the supply voltage. The RF filter in the second RF filter topology is configured to filter the supply voltage from the LDO regulation circuit to reduce a ripple variation in a supply voltage level of the supply voltage. As such, the RF filter provides greater versatility.

This disclosure relates to radio frequency (RF) power converters and methods of operating the same. In one embodiment, an RF power converter includes an RF switching converter, a low-drop out (LDO) regulation circuit, and an RF filter. The RF filter is coupled to receive a pulsed output voltage from the RF switching converter and a supply voltage from the LDO regulation circuit. The RF filter is operable to alternate between a first RF filter topology and a second RF filter topology. In the first RF filter topology, the RF filter is configured to convert the pulsed output voltage from a switching circuit into the supply voltage. The RF filter in the second RF filter topology is configured to filter the supply voltage from the LDO regulation circuit to reduce a ripple variation in a supply voltage level of the supply voltage. As such, the RF filter provides greater versatility.

A power supply device includes a first converter which converts an input voltage to a first voltage, a second converter which converts the first voltage from the first converter to a second voltage, a voltage comparison section which compares the first voltage outputted from the first converter with a predetermined reference voltage, a voltage comparison result output section which outputs a first signal until the first voltage is determined to be higher than the predetermined reference voltage by the voltage comparison section and retains a second signal as an output after the first voltage is determined to be higher than the predetermined reference voltage, and a converter control section which controls the second converter to stop when the first signal is outputted from the voltage comparison result output section and controls the second converter to operate when the second signal is outputted from the voltage comparison result output section.

A switching power converter includes a voltage source that provides an input voltage Vin to an unregulated DC/DC converter stage and at least one buck-boost converter stage to produce a desired output voltage Vout. The unregulated DC/DC converter stage is adapted to provide an isolated voltage to the at least one regulated buck-boost converter stage, wherein the unregulated DC/DC converter stage comprises a transformer having a primary winding and at least one secondary winding and at least one switching element coupled to the primary winding. The at least one buck-boost converter stage is arranged to operate in a buck mode, boost mode or buck-boost mode in response to a mode selection signal from a mode selection module. By influencing the pulse width modulation output power controller the at least one buck-boost converter stage is arranged to produce one or multiple output voltages.

A power converting circuit includes an upper gate switch, a transistor, a current source circuit, a comparator circuit, a delay circuit, and a pulse width modulation signal generating circuit. The transistor and the current source circuit provide a reference signal. The comparator circuit generates a comparing signal according to the reference signal and an output signal provided by the upper gate switch. The delay circuit generates a delay signal according to the comparing signal and a clock signal. The pulse width modulation signal generating circuit generates a control signal for the upper gate switch according to the delay signal and the clock signal for configuring the conduction status of the upper gate switch. The power converting circuit adjusts the conduction time of the upper gate switch according to the reference signal and the output signal.