Abstract: A series resonant Dc-DC converter powers an audio amplifier as a load. The series resonant DC-DC converter may include a power input stage, a switching stage, a series resonant stage, a transformer stage and a power output stage. The series resonant DC-DC converter further may include a clamping stage and a leakage inductance canceling stage. The clamping stage may operate to clamp an excess voltage generated at least by a leakage inductance and a parasitic capacitance. The leakage inductance canceling stage may operate to generate a voltage drop corresponding to a voltage drop generated by the leakage inductance. The generated voltage drop may be subject to clamping. The clamping stage may operate under all load conditions without any influence of the leakage inductance. As a result, the series resonant converter may achieve improved load regulation.

Abstract: A switching mode power supply and a corresponding method of protection operation is presented. A switching controller of the switching mode power supply receives current sensing information corresponding to the current flowing through a main switch and feedback information corresponding to an output voltage through a single terminal, and performs a protection operation when the voltage at the terminal is maintained to be lower than a reference voltage for more than a predetermined time frame. The power supply requires a low number of terminals, while preserving the protection operation function.

Abstract: In one embodiment, a secondary side power supply controller is configured to enable a secondary side power switch independently of a state of a drive signal used to control a primary side of the power supply.

Abstract: An inverter device includes an inverter circuit, an inverter driving unit, and a clamp diode. The inverter circuit includes an upper arm unit and a lower arm unit connected in series. The upper arm unit and the lower arm unit include switching elements that drive a load. The inverter driving unit includes a high-withstand-voltage IC that drives the switching elements of the upper arm unit and the lower arm unit. The high-withstand-voltage IC has a first terminal for supplying a reference voltage to the lower arm unit and a second terminal for supplying a high-voltage to the upper arm unit. The clamp diode clamps a potential difference between the first terminal and the second terminal.

Abstract: In one embodiment, a start-up controller for a PWM power supply controller is formed to generate a current that is substantially constant for changes in temperature and for changes in an output voltage received by the start-up controller.

Abstract: A three-phase electronic electricity meter that includes a power supply circuit operable to create a constant voltage output when receiving a variable voltage input. The power supply circuit of the electricity meter receives a three-phase line voltage and converts the variable three phase line voltage to a constant DC output. The power supply circuit includes a current limiting circuit to suspend operation of the power converter when the current exceeds a selected value. The power supply circuit includes an over voltage protection that limits the maximum voltage applied to the switching component of the power supply circuit. Both the over voltage protection circuit and the current limiting circuit suspend operation of the power converter to prevent damage to the operating components of the power supply circuit.

Abstract: Disclosed is an invention relating to a power supply for use in an apparatus for measuring electrical energy, comprising, in one embodiment, a first switching device, a device for storing electrical charge in electrical connection with the first switching device, a second switching device in electrical connection with the device for storing electrical charge, a first device for controlling the flow of current in electrical connection with the second switching device, and a third switching device in electrical connection with the first device for controlling the flow of current, wherein the first device for controlling the flow of current enables an input voltage to be applied to the second switching device when the input voltage is below a predetermined amount, and enables the input voltage to be applied to the second and third switching devices when the input voltage is above the predetermined amount.

Abstract: A switching mode power supply and a method for outputting voltage therefrom are provided, where a transformer receives rectified alternating current (AC) voltage and transforms a voltage value or a current value, a switching transistor is connected to one end of a first coil and controls a level of power supplied to the first coil, a heat sink is positioned adjacent to the switching transistor and attenuates electromagnetic wave noise of the switching transistor; and a capacitive device is set up in an electric power line connecting the heat sink to a first side grounding end coupled with the other end of the first coil of the transformer. Accordingly the switching mode power supply can be miniaturized while effectively attenuating the electromagnetic wave noise from the switching transistor.

Abstract: A power supply comprises a rectifier, a transformer, a switching member, a controller and a voltage blocking clamp. A power supply can receive an alternating current (AC) input voltage having any magnitude within a wide range of AC input voltage magnitudes and can produce from any such AC input voltage magnitude a direct current (DC) output voltage. The voltage blocking clamp comprises at least one transistor connected between the rectifier and the transformer and switching member that limits the amount of rectified AC input voltage applied to the transformer and switching member to a predetermined amount when the rectified input voltage exceeds that predetermined amount. When the rectified input voltage exceeds the predetermined amount, the amount of the rectified input voltage above the predetermined amount is applied to the at least one transistor instead of the transformer and switching member.

Abstract: A power converter comprises an inductor (L) and a main switch (M1) having a main current path, the inductor (L) and the main current path are arranged in series to receive a DC-input voltage (VIN). A control circuit (CC) controls on-periods (Ton) and/or off-periods (Toff) of the main switch (M1) to stabilize an output voltage (VO) supplied to a load (LO). The control circuit (CC) further has an input (IN) to receive a measuring signal (MS) to protect the main switch (M1) against situations of overvoltage. A measuring circuit (MC) is coupled to a junction (J1) of the inductor (L) and the main current path to obtain the measuring signal (MS) which is indicative of a voltage across the main current path. Preferably, the measuring circuit (MC) comprises a peak-clamp.

Abstract: A switching power source apparatus has a series circuit connected to both ends of a DC power source Vdc1 and having a reactor L3, a primary winding 5a of a transformer T, and a switch Q1, a series circuit connected to both ends of the primary winding and having an auxiliary switch Q2 and a clamp capacitor C3, a saturable reactor SL1 connected in parallel with the primary winding, a rectifying-smoothing circuit D1, D2, L1, C4 for rectifying and smoothing a voltage generated on a secondary winding 5b, and a control circuit 10 for alternately turning on/off the switches Q1 and Q2 and turning off the switch Q2 if a current of the switch Q2 increases due to saturation of the saturable reactor SL1. The reactor L3 is made of leakage inductance between the primary and secondary windings.

Abstract: The present invention proposes an over-voltage protection apparatus for a power converter. The over-voltage protection apparatus has an oscillator outputting a clock signal. Simultaneously, by comparing a sense signal with a threshold signal, an over-voltage comparative unit outputs a protection signal to an accumulating trigger unit. Next, the accumulating trigger unit is accumulating and counting the protection signal in response to the clock signal. The accumulating trigger unit further outputs an off signal to a latch unit as a period of the protection signal reaches a predetermined clock count. In response to the off signal, the latch unit outputs a latch signal to a driving output unit for disabling a switching signal to a power switch. Therefore, the power switch is turned off, and the object of the over-voltage protection can be accomplished.

Abstract: The present invention discloses a power supply device for outputting a stable programmable power supply, which comprises a transformer disposed at a DC output end of the power supply device, and a clamp circuit connected to a secondary current of the transformer. Since the clamp circuit is disposed on the secondary current of the transformer, therefore it does not require a high DC voltage to drive the clamp circuit. The clamp circuit can release the high voltage produced when the metal oxide semiconductor field effect transistor (MOSFET) is off, and thus reducing the high voltage borne by the MOSFET to enhance the reliability of the MOSFET. Additionally, the present invention can prevent the transformer from being saturated due to magnetic leakage, inductance, and stored energies released or eliminated from the transformer.

Abstract: Feedback circuits capable of preventing output voltage overshoot in closed-loop DC regulated power supplies are presented. The circuits employ hysteresis at the input of an operational amplifier to improve the response time of the feedback circuits to a rising output voltage reaching a threshold. The feedback circuits substantially reduce, if not prevent, output voltage overshoot during start-up and hard and soft output shorts.

Abstract: The present invention is directed to a switching power supply apparatus (100) adapted for controlling switching operation of a switching FET (125) which carries out switching of rectified and smoothed output of a primary side rectifying/smoothing circuit (115) by a switching control circuit (130) including a hysteresis low voltage malfunction preventing circuit, wherein lowering time until rated voltage at which constant voltage by self-discharge can be maintained is caused to be longer than time until operating voltage of the low voltage malfunction preventing circuit of the switching control circuit of the primary side at the time of no load, and lowering time until rated voltage at which constant voltage by self-discharge can be maintained is caused to be shorter than time until operating voltage of the voltage malfunction preventing circuit at the time of ordinary load to thereby suppress power consumption as minimum as possible to realize energy-saving at the time of standby.

Abstract: A power supply protecting the electric device circuit when over-voltage is applied, is provided. The power supply has a rectifying unit rectifying AC power externally supplied, into first and second DC power and outputting the first and the second DC power; a main power supply transformer boosting the first DC power and supplying the boosted first DC power to the electric device circuit; a switching controlling unit driven by the second DC power, performing the operation on the main power supply transformer that causes the first DC power to be boosted when the second DC power is received; and a controlling unit determining whether the second DC power is to be supplied to the switching controlling unit, wherein the controlling unit senses the voltage supplied to the electric device circuit and interrupts supplying the second DC power to the switching controlling unit if the sensed voltage exceeds a given value.

Abstract: A switching mode power supply includes a rectifier configured to convert AC power to a first DC power, an output unit configured to convert the first DC power to a second DC power under the control of a first switch, and a pulse width modulation generator coupled to control the first switch. The pulse width modulation generator has a regulator configured to regulate the first DC power. The regulated first DC power powers the pulse width modulation generator. The regulator includes a second switch coupled to control a transmitter so that when the second switch is in a first state the transmitter transmits the first DC power to a capacitor to charge the capacitor to thereby increase the regulated first DC power, and when the switch is in a second state the transmitter does not transmit the first DC power to the capacitor to thereby allow the charge in the capacitor to reduce and in turn the regulated first DC power to reduce.

Abstract: Dissipative clamping apparatuses and methods for electrical circuits. In one aspect of the invention, In one aspect of the invention, a method includes switching a power supply input on an energy transfer element, regulating a power supply output by switching the power supply input on the energy transfer element, clamping a voltage on the energy transfer element to a clamp voltage and varying the clamp voltage in response to the power supply input. In another aspect, an electrical circuit includes a dissipative clamp circuit coupled to an input of the electrical circuit. An inductive element is coupled between the dissipative clamp circuit and an output of the electrical circuit. A switch is coupled in series with the inductive element.

Abstract: The present invention is directed to an auxiliary active clamp circuit and a method of clamping a voltage of a rectifier switch associated with a power converter. The power converter includes a main active clamp circuit associated with a main power switch coupled to a primary winding of a transformer and a rectifier switch coupled to a secondary winding of the transformer. The main power switch conducts during a main conduction period of the power converter and the rectifier switch conducts during an auxiliary conduction period of the power converter. In one embodiment, the auxiliary active clamp circuit includes an auxiliary clamp capacitor, coupled across the rectifier switch, that stores a clamping voltage substantially equal to an off-state voltage of the rectifier switch.

Abstract: A DC/DC converter device is provided that employs a clamp device to limit the peak voltage of a main power switch coupled to a primary winding of a transformer. The clamp device is driven employing a driver circuit coupled to a level shifter circuit. The level shifter circuit shifts the voltage level transitions of a clamp device drive signal from a first voltage level to a second voltage level range to drive the clamp device with a voltage that is outside a voltage range of an input supply voltage.

Abstract: Feedback circuits capable of preventing output voltage overshoot in closed-loop DC regulated power supplies are presented. The circuits employ hysteresis at the input of an operational amplifier to improve the response time of the feedback circuits to a rising output voltage reaching a threshold. The feedback circuits substantially reduce, if not prevent, output voltage overshoot during start-up and hard and soft output shorts.

Abstract: A gate driver and a method of driving a switch for use with a power converter having a main active clamp circuit associated with a main power switch coupled to a primary winding of a transformer and a rectifier switch coupled to a secondary winding of the transformer. The main power switch conducts during a main conduction period of the power converter and the rectifier switch conducts during an auxiliary conduction period of the power converter. In one embodiment, the gate driver includes a DC offset bias circuit, coupled to a secondary winding of the transformer, that provides a gate drive signal having a DC bias voltage to a gate terminal of the rectifier switch.

Abstract: Dissipative clamping apparatuses and methods for electrical circuits. In one aspect of the invention, In one aspect of the invention, a method includes switching a power supply input on an energy transfer element, regulating a power supply output by switching the power supply input on the energy transfer element, clamping a voltage on the energy transfer element to a clamp voltage and varying the clamp voltage in response to the power supply input. In another aspect, an electrical circuit includes a dissipative clamp circuit coupled to an input of the electrical circuit. An inductive element is coupled between the dissipative clamp circuit and an output of the electrical circuit. A switch is coupled in series with the inductive element.

Abstract: A power converter is provided that operates with a wide range input and provides the required hold up time using a smaller, less costly hold-up capacitor. A charging circuit is provided to charge a capacitor through an auxiliary winding. The power converter includes circuitry for channeling the energy from the capacitor to the converter to provide hold-up time during input power loss conditions, while having better utilization of stored energy. The power converter of the present invention also provides this function using fewer and lower cost components than prior art devices.

Abstract: Dissipative clamping apparatuses and methods for electrical circuits. In one aspect of the invention, In one aspect of the invention, a method includes switching a power supply input on an energy transfer element, regulating a power supply output by switching the power supply input on the energy transfer element, clamping a voltage on the energy transfer element to a clamp voltage and varying the clamp voltage in response to the power supply input. In another aspect, an electrical circuit includes a dissipative clamp circuit coupled to an input of the electrical circuit. An inductive element is coupled between the dissipative clamp circuit and an output of the electrical circuit. A switch is coupled in series with the inductive element.

Abstract: A pulse-width modulated apparatus to convert an input voltage to an output voltage at advantaged duty-cycles utilizes more than two switches in a converter design. The switches implement current paths that allow a single primary winding to be formed of primary winding segments. Intermediate points in the transformer primary winding are connected to switches and diodes such that during the OFF phase of the duty-cycle, the transformer segments discharge more quickly, thereby allowing the ON Phase of the duty-cycle to be longer than the OFF phase. During the OFF phase, the switches isolate the segments from each other while the diodes provide a magnetizing current discharge path. An output stage connected across the secondary winding regulates the output voltage by implementing a forward converter.

Abstract: Dissipative clamping apparatuses and methods for electrical circuits. In one aspect of the invention, In one aspect of the invention, a method includes switching a power supply input on an energy transfer element, regulating a power supply output by switching the power supply input on the energy transfer element, clamping a voltage on the energy transfer element to a clamp voltage and varying the clamp voltage in response to the power supply input. In another aspect, an electrical circuit includes a dissipative clamp circuit coupled to an input of the electrical circuit. An inductive element is coupled between the dissipative clamp circuit and an output of the electrical circuit. A switch is coupled in series with the inductive element.

Abstract: A parallel power supply system with an over-voltage protection circuit is provided. The parallel power supply system includes two power supplies which are paralleled for providing a stable DC output voltage, two isolated diode electrically, each of which is coupled between an output of each power supply and the DC output voltage for isolating outputs of the power supplies and the DC output voltage respectively, two voltage feedback controllers, each of which feeds back an output voltage of each power supply to control output voltages of power supplies at a predetermined value respectively, two resistors, and two bypass diodes used for forming a bypass connection which operates during the over-voltage outputting period.

Abstract: A crowbar circuit comprises an over-voltage detector that monitors the output voltage of a synchronous DC/DC converter. When the output voltage rises above a predetermined threshold, the detector applies a control signal to a MOSFET switch that is already in use as part of a rectifier in the converter. The control signal overrides a periodic switching signal applied to the gate of the MOSFET, causing it to conduct continuously and thereby apply a shunt path for the output current of the rectifier. The control signal may be continuously applied until the converter is manually reset. Because the voltage across the conducting MOSFET is small and it can be turned on quickly, the MOSFET rapidly clamps the DC/DC converter's output to a voltage low enough to avoid damage to integrated circuitry powered by the converter.

Abstract: An intermittent switching power supply circuit prevents excessive output power on a secondary side of a circuit. An intermittent oscillator is alternately switched on and off to maintain output voltage and/or current roughly constant. An output power monitoring circuit monitors output power from a rectifying/smoothing circuit. A control circuit outputs a stop control signal to an control terminal of the intermittent oscillator when the output power monitoring circuit determines that the output voltage and/or current exceeds a reference value. The protection circuit and a photocoupler receiver element are connected in parallel with the control circuit. Where a circuit error occurs and the photocoupler receiver element fails to cycle the intermittent oscillator between active and inactive conditions for a predetermined time, the protection circuit provides a backup which outputs a stop control signal to stop oscillation of the intermittent oscillator element.

Abstract: The present invention provides a ring choke converter, a kind of power supply, and method thereof. In addition to the transformer, the switch component, the positive feedback circuit and the regulation control circuit in a conventional RCC, the present invention provides a control circuit partially powered by terminal of the opposite polarity at the feedback winding of the transformer. With the circuit design of the control circuits disclosed in this invention, under-voltage protection (UVP), over-voltage protection, and overload protection, together with stable output voltage are all achieved.

Abstract: A restart circuit for a power supply of an electronic system such as a computer system for delaying the restart of the power supply until a power supply output is in compliance with a specified parameter. In one embodiment, the specified parameter is a particular threshold voltage level and the power supply output is in compliance when it is less than the particular threshold voltage level. In another embodiment of a restart circuit, the specified parameter is a rate of decay in a voltage level and the power supply output is in compliance when it is decaying at a rate less than the predetermined rate. In one embodiment, delaying the restart of the power supply permits components of the system to be reset when the voltage level of the power supply output is in a known state.

Abstract: Dissipative clamping apparatuses and methods for electrical circuits. In one aspect of the invention, In one aspect of the invention, a method includes switching a power supply input on an energy transfer element, regulating a power supply output by switching the power supply input on the energy transfer element, clamping a voltage on the energy transfer element to a clamp voltage and varying the clamp voltage in response to the power supply input. In another aspect, an electrical circuit includes a dissipative clamp circuit coupled to an input of the electrical circuit. An inductive element is coupled between the dissipative clamp circuit and an output of the electrical circuit. A switch is coupled in series with the inductive element.

Abstract: The power supply device includes a DC-DC converter circuit having a power switch and a driving stage. The driving stage has a compensation terminal on which a compensation voltage is present, and which receives a biasing current. The driving stage includes a control circuit having an output terminal connected to a control terminal of the power switch and disconnection-detecting circuitry connected to the compensation terminal and generating a signal for permanent turning-off of the power switch when the biasing current drops below a current-threshold value. The driving stage moreover includes over-voltage detecting circuitry connected to the compensation terminal and generating a signal for temporary turning-off of the power switch when the compensation voltage exceeds a voltage-threshold value.

Abstract: Dissipative clamping apparatuses and methods for electrical circuits. In one aspect of the invention, In one aspect of the invention, a method includes switching a power supply input on an energy transfer element, regulating a power supply output by switching the power supply input on the energy transfer element, clamping a voltage on the energy transfer element to a clamp voltage and varying the clamp voltage in response to the power supply input. In another aspect, an electrical circuit includes a dissipative clamp circuit coupled to an input of the electrical circuit. An inductive element is coupled between the dissipative clamp circuit and an output of the electrical circuit. A switch is coupled in series with the inductive element.

Abstract: A protection circuit arranged in a switching power supply system for protecting the switching power supply system is provided. The protection circuit includes a detecting circuit electrically connected to a switching controller of the switching power supply system for providing a trigger signal when a supply voltage drops to an under-voltage level, and a protection circuit electrically connected to the detecting circuit for providing a signal to protect the switching power supply system when the detecting circuit provides the trigger signal to the protection circuit. A method for protecting an switching power supply system is provided. The method includes the steps of detecting that the reference voltage signal disappears when the supply voltage is smaller than a minimum of operating voltage and providing a trigger signal, and providing an protection to protect the switching power supply system in response to the trigger signal.

Abstract: In order to achieve complete short-circuit protection irrespective of a location of a short-circuit in a switched-mode power supply having a controllable switch in a primary circuit, the controllable switch is opened when a voltage drop across an electrolytic capacitor in a primary circuit falls below a threshold value which can be predetermined. For this purpose, a capacitive voltage device containing two capacitances is connected in parallel with the electrolytic capacitor. A potential at a center tap of the capacitive voltage divider is compared in a comparator with a reference voltage, which opens the controllable switch when the potential at the center tap falls below the reference voltage.

Abstract: A clamp circuit for limiting output voltage from a power supply secondary inductor to a ground when a first secondary node has a first secondary node voltage above a predetermined value relative to ground includes a silicone controlled rectifier and a control circuit. The silicone controlled rectifier has a first anode that is electrically coupled to the first secondary node of the secondary inductor, a first cathode that is electrically coupled to the secondary ground, and a first gate. The control circuit is electrically coupled to the first secondary node and to the gate of the silicon controlled rectifier. The control circuit senses the first secondary node voltage and applies a control voltage to the gate of the silicon controlled rectifier when the first secondary node voltage is above the predetermined value.

Abstract: A power chip set for a switching mode power supply includes a high voltage chip and a control unit chip. The high voltage chip contains a switching power metal-oxide-semiconductor (MOS) transistor being turned on/off under control of an output signal from the control unit, and a junction field effect transistor (JFET) coupled between a drain of the switching power MOS transistor and a power terminal of the control unit to serve as a start up element for driving the control unit during initiation, in which the JFET has a negative threshold voltage and the absolute value thereof is equal to the voltage for driving the control unit. The JFET structure in the high voltage chip further includes a Zener diode for over voltage protection of the control unit. The high voltage chip further contains a current-sense power MOS transistor coupled with the drain of the switching power MOS transistor for detecting a drain current of the switching power MOS transistor. The chip set can be packaged into a power module.