Abstract: Provided is a voltage regulator including a ripple rejection ratio improving circuit that requires no readjustment such as trimming for each output voltage. An output of the ripple rejection ratio improving circuit is connected to a back gate of a MOS transistor forming a current mirror section or a back gate of an input stage MOS transistor of an error amplifier circuit. With this construction, a ripple at a power supply terminal or a ground terminal and a ripple at an output terminal can be canceled with each other, thereby being capable of improving the ripple rejection ratio.

Abstract: A power Y-adapter provides power at a high voltage to an output end from at least two input ends to which power of a lower voltage and a phase difference is provided and includes a first polarity sensitive current isolation device, a second polarity sensitive current isolation device, a control section, and an output section. When the voltage signals supplied to the hot wire terminals of the first input connector and the second input connector sufficiently are out of phase, the Y-adapter can produce a voltage of higher magnitude between the first and the second hot wire terminals of the output connector.

Abstract: A DC-DC converter includes: a high-side MOSFET as a main switching element which is driven by using a bootstrap capacitor; a low-side MOSFET as a synchronous rectifier, wherein a series circuit of the high-side MOSFET and the low-side MOSFET is connected to a DC power supply; and a coil and a smoothing capacitor, which are serially connected between the drain and the source of the low-side MOSFET; an overvoltage protection unit, which clamps an overvoltage; an overcurrent interrupting unit, which interrupts an overcurrent that flows when the overvoltage protection unit clamps the overvoltage; and a protection circuit, wherein the protection circuit includes: a differential-voltage detecting unit detecting the voltage of both ends of the bootstrap capacitor; and a control unit that, when the voltage detected by the differential-voltage detecting unit exceeds a predetermined value, turns OFF the low-side MOSFET and turns ON the high-side MOSFET.

Abstract: A time sequence control circuit that can control time sequence of a computer. After the computer is turned on, a power supply terminal outputs a high level enabling signal to an enabling pin of a power supply circuit, the power supply circuit is active. A power supply pin of the power supply circuit outputs a standard voltage to a power pin of each of the motherboard components. A first electronic switch is turned on, a second electronic switch is turned off, and a power supply state pin of the power supply circuit outputs a high level power supply state signal to a power state input pin of a main chip after the power supply circuit outputs the standard voltage.

Abstract: The invention relates to a device for controlling the voltage of a cell of a fuel cell, characterized in that said control device comprises a first transistor (Q1) associated with the cell, which is connected to the cell via the base thereof and to a current generator, and a control voltage source (VRi) inserted between the cell and the first associated transistor (Q1), the control voltage source supplying a control voltage equal to the voltage differential between the first and second threshold voltages, such that: when the cell has a voltage (V1) higher than a first threshold voltage, the first transistor (Q1) has a voltage (Vbe1), at the terminals of the base-emitter junction thereof, which is higher than the second threshold voltage, and which conducts the current, and, when the cell has a voltage (V1) which is lower than the first threshold voltage, the first transistor (Q1) has a voltage (Vbe1), at the terminals of the base-emitter junction thereof, which is lower than the second threshold voltage and w

Abstract: The invention relates to a method for the data transmission from an emitter (1) to a receiver (2) in an AC voltage network, comprising a distributor (3) and at least one user group (4) with one or several users (5), wherein the emitter (1) feeds a signal to the AC voltage network by means of a power source (6).

Abstract: The power supply controller performs the power-supply-path protection operation to restrict power supply through the switch element if a value of temperature increase of the power supply path W with respect to the reference temperature To exceeds the temperature threshold value and remove the restriction if the temperature decreases to the temperature threshold value or lower. And the controller performs the switch protection operation to restrict the power supply through the switch element if the value of the flowing current exceeds the current threshold value and remove the restriction after the reference time H elapses. And also the controller adds the additional value F to the value of temperature increase on condition that the value of the flowing current exceeds the current threshold value in the power supply protection operation and compares a post-addition temperature to the temperature threshold value.

Abstract: A power supply system of the present invention aims to achieve optimization of the efficiency and therefore includes: z (z is a natural number equal to or larger than 2) power supplies (PS-1 to PS-z) connected in parallel; and a controller (8) for the number of power supplies in operation which controls the number of power supplies in operation among the power supplies (PS-1 to PS-z).

Abstract: A DC-DC converter of a liquid crystal display (LCD) apparatus is provided comprising a first capacitor connected between a first node and a second node, a second capacitor connected between a third node and a fourth node, and a first diode connected between the input terminal and the first node.

Abstract: The source of FET is connected to a battery voltage +V through a fuse, while the drain of FET is connected to an electric load. The gate of FET is connected to the connection node of a capacitor and a resistor of a serial circuit configured with the capacitor the resistor. The serial circuit is connected in series with FET. The source and drain of FET are connected to both ends of the capacitor. The gate of FET is connected to the connection node of resistors. The resistor is connected to FET.

Abstract: A power controller system configured to electrically supply a load via a circuit is provided. The system comprises, a switching device provided in an electrical pathway for supplying current to the load, a controller configured to open the switching device when a current through or voltage across the switching device exceeds a predetermined level; and an electrical pathway provided parallel to the load to enable load current to continue to flow through the parallel electrical pathway and the load when the switching device is open to dissipate inductive energy stored in the circuit connecting the parallel electrical pathway to the load.

Abstract: A controller CT1 switches on a first switch SW1, and the direct-current voltage given from a power source BAT flowing through a first inductor L1 is smoothed by a capacitor C1 and is output from an output terminal OUT1. After a specified period of time has elapsed since the first switch SW1 was turned off by the controller CT1, the second switch SW2 and the third switch SW3 are turned on approximately at the same time. The electric current which was flowing through the first inductor L1 is branched into the second switch SW2 and the third switch SW3, and the electric current flowing through the parasitic diode Dp1 of the second switch SW2 is reduced. As a result, when the second switch SW2 is turned off, the recovery current flowing through the parasitic diode Dp1 is reduced.

Abstract: A load control device includes: a main switching unit which has a main switch element connected in series to an AC power source and a load and controls the supply of power to the load; a manipulation switch that outputs a start-up signal for starting at least the load; a control unit which controls the opening and closing of the main switching unit; a first power source unit supplying a stable voltage to the control unit; and a second and a third power source unit each supplying power to the first power source unit. The load control device is characterized in that upon receiving the start-up signal, the control unit outputs an initial drive signal, for closing the main switch element, to the main switching unit before a power source supplying power to the first power source unit is switched from the second to the third power source unit.

Abstract: The present invention is related to an electrical energy conversion circuit device (190), a method (600) of operating an electrical energy conversion circuit device, an electrical apparatus (500) and a computer program. The circuit device (190) allows earth connection and comprises two parallel connected buck-boost converters for converting a direct input voltage (110) into a direct output voltage (120). The converters are adapted to generate two phase-shifted currents (131, 141) that are received by an output capacitor (160). Due to the phase-shift, a current ripple is reduced. The direct output voltage (120) and the direct input voltage (110) preferentially have a common potential (114) and are of opposite polarities. Therefore, a second voltage of high magnitude, the sum of the direct input voltage (110) and the direct output voltage (120) is also provided.

Abstract: An electric power conversion device includes a power conversion circuit for receiving electric power from an overhead wire through an LC filter circuit composed of a reactor and a capacitor and converting the electric power to output and a control unit for controlling the power conversion circuit, wherein the control unit is provided with a delay unit for delaying the voltage across the capacitor so as to produce a first control signal, produces a second output voltage instruction from the first control signal and a first output voltage instruction specifying the magnitude of the output voltage of the converted power, and controls the power conversion circuit based on the second output voltage instruction.

Abstract: A drive circuit supplies a charging current via a charging path to drive the control terminal of a voltage-controlled switching device, with a resistor and a switching device being connected in series in the charging path. A control circuit in an integrated circuit of the drive circuit operates an internal switching device such as to selectively enable/interrupt the charging current and to regulate the voltage drop across the resistor to a fixed value. The switching device connected in the charging path can be readily changed from the internal switching device to an external switching device, in accordance with the operating requirements of the driven switching device.

Abstract: If a power supply path is in an abnormal state, a power-supply-path protection circuit of a power supply controller inhibits a switching circuit that switches on/off power supply from a power source to a load from power supply, using data related to a protection-current temperature characteristic line set by a characteristic setting circuit. The protection-current temperature characteristic line has a characteristic in which a protection current value is constant corresponding to increase in an ambient temperature or a negative characteristic in which the protection current value reduces corresponding to increase in the ambient temperature. Within a temperature range equal to or lower than an supposed maximum ambient temperature around the power-supply-path, the protection-current temperature characteristic line and a power-supply-path temperature characteristic line have a relation that the protection-current value is equal to or lower than an allowable current value at an identical ambient temperature.

Abstract: A voltage stabilizing circuit including an input port, an output port, a transistor, a diode, a three-terminal voltage regulating reference source, a first resistor, and a second resistor. The transistor has a collector terminal and an emitter terminal connected to the input port and the output port, respectively. The diode has an anode connected to the input port and a base terminal of the transistor. The three-terminal voltage regulating reference source has an anode connected to ground, a cathode connected to the input port and a cathode of the diode, and a reference terminal The first resistor is connected between the cathode of the diode and the reference terminal of the three-terminal voltage regulating reference source. The second resistor is connected between ground and the reference terminal of the three-terminal voltage regulating reference source.

Abstract: A DC-DC converter is driven by single high input voltage, and includes a voltage converter circuit and a control circuit. The increase of the occupied area of the DC-DC converter is suppressed. The DC-DC converter includes an input terminal to which input voltage is applied; a voltage converter circuit connected to the input terminal, and including a first transistor; a control circuit configured to control the voltage converter circuit, and including a second transistor including a silicon material in a channel formation region; and a third transistor provided between the input terminal and the control circuit, and configured to convert the input voltage into power supply voltage that is lower than the input voltage. The first transistor and the third transistor include an oxide semiconductor material in channel formation regions. The first transistor and the third transistor are stacked over the second transistor with an insulating film provided therebetween.

Abstract: A DC-DC converter having a first and a second switch, an input diode, a magnetizing inductor, a resonant capacitor, a resonant inductor, an output diode and an output filter capacitor. The first and second switches are turned on alternatively. When the first switch is turned on, an input voltage is coupled to an anode of the input diode that has a cathode coupled to a first terminal of the magnetizing inductor. The second switch is designed to short a second terminal of the magnetizing inductor to a ground. The resonant capacitor and inductor, which are coupled in series, are disposed between the second terminal of the magnetizing inductor and the ground. A connection node between the resonant capacitor and inductor is coupled to the output filter capacitor, via the output diode, to regulate a voltage of the output filter capacitor. The regulated voltage is used in powering a load.

Abstract: There is disclosed a converter controller which can simply and early detect an abnormality of an auxiliary circuit constituting a soft switching converter. On turning off a first switching element, a controller detects a voltage between both the ends of a snubber capacitor and a voltage between both the ends of the first switching element, to obtain a difference voltage. The controller compares the obtained difference voltage with a voltage threshold value stored in a memory (not shown) to judge whether or not the difference voltage is larger than the voltage threshold value. When the difference voltage is smaller than the voltage threshold value, the controller judges that an auxiliary circuit is normal, to end processing, whereas when the difference voltage is not less than the voltage threshold value, the controller judges that a failure (an open failure) occurs in the auxiliary circuit, to shift to a fail safe operation, thereby ending the processing.

Abstract: 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.

Abstract: A switching power source according to one embodiment includes a first transistor and a second transistor. The first transistor is connected to a positive electrode of a DC voltage source. The second transistor is connected between the first transistor and a negative electrode of the DC voltage source. The first transistor and the second transistor are alternately placed in conducting state. A gate signal is applied to a gate terminal of the first transistor with reference to a voltage of a terminal of the first transistor that is connected to the positive electrode. A gate signal is applied to a gate terminal of the second transistor with reference to a voltage of a terminal of the second transistor that is connected to the negative electrode. The first transistor and the second transistor are configured with wide bandgap semiconductors of mutually different materials, respectively.

Abstract: Each switching element of a charge pump circuit of a voltage regulator comprises a relatively small-sized MOS transistor associated with a relatively large-sized MOS transistor connected in parallel. Only the small transistors are switched in a first mode of operation, while the large transistors are switched in a second mode of operation. In this manner the switching losses in the first mode of operation can be decreased.

Abstract: A DC-DC converter circuit includes first to sixth semiconductor switches and an inductor. The first to third semiconductor switches are connected to one end of the inductor. The fourth to sixth semiconductor switches are connected to the other end of the inductor. A first voltage supply is connected to opposite ends of the first and fourth semiconductor switches from the ends of the first and fourth semiconductor switches connected to the inductor. A second voltage supply is connected to opposite ends of the second and fifth semiconductor switches from the ends of the second and fifth semiconductor switches connected to the inductor. The first voltage supply and the second voltage supply are both connected to opposite ends of the third and sixth semiconductor switches from the ends of the third and sixth semiconductor switches connected to the inductor.

Abstract: A voltage conversion apparatus is disclosed in which a current passes through first and second loop circuits alternately in accordance with ON/OFF operation of a first switching element provided in the first circuit. The direction of a magnetic field through the first loop circuit formed at the ON operation is the same as a direction of a magnetic field through the second loop circuit formed at the OFF operation. The first loop circuit and the second loop circuit are provided on opposite sides of a printed circuit board, respectively, in such a manner that the first loop circuit and the second loop circuit are opposed to each other. A heat sink is provided on a surface of the printed circuit board. A solid pattern of a metal material is provided on an inner layer of the printed circuit board to be connected to the heat sink via a through hole.

Abstract: An appliance's control and sensing circuit selectively applies AC electrical power to a load (72). The circuit includes a relay (44) having contacts (52) connected in series between an AC power source and the load (72). When energized, the relay's electromagnetic coil (54) changes the contacts (52) to supplying electrical power to the load (72) or conversely. The control and sensing circuit measures AC voltage induced in the coil (54) by an alternating magnetic field produced by AC electrical current supplied to the load (72) through the relay's contacts (52). A microcontroller (46) included in the control and sensing circuit: 1. measures the AC voltage produced by the coil (54); 2. compensates the measured voltage for inductive coupling between the AC current flowing through the contacts (52) and the coil (54); and 3. determines various characteristics of the AC power supplied to the load (72).

Abstract: Embodiments for methods and apparatuses for controlling a skew time of switches of a switching voltage regulator are disclosed. One method includes generating a switching voltage through closing and opening of a series switch and a shunt switch as controlled by a series switch control signal and a shunt switch control signal. An error signal is generated that is proportional to a relative displacement of an on-interval of the series switch and an off-interval of the shunt switch. A relative delay of the series switch control signal and the shunt switch control signal is adjusted based on the error signal, and a regulated output voltage is generated based upon the switching voltage.

Abstract: A power converter includes an input terminal configured to be connected to a power supply, an output terminal, and a first switching element coupled between the input terminal and the output terminal. The first switching element includes a semiconductor multilayer structure formed on a substrate and made of a nitride semiconductor, a gate electrode formed on the semiconductor multilayer structure, a first and a second ohmic electrode, and a back electrode formed on a back surface of the substrate. A potential is supplied from the power supply connected to the input terminal to the back electrode so that a potential difference between the back surface and the second ohmic electrode is reduced. When the first switching element is in the on-state, a positive voltage bias is applied to the back electrode.

Abstract: A high side switch circuit includes a switch electrically connected between input and output terminals, a gate control unit, and an over-current sensor unit. The over-current sensor unit includes a resistive element and a comparator. The comparator senses an over-current if a voltage of the resistive element exceeds a threshold voltage. The comparator is adjusted in advance such that the detected voltage at the time of over-current exceeds the threshold voltage. Even if accuracy of resistance value of the resistive element is not high, accuracy of detecting over-current can be improved by adjusting the comparator.

Abstract: A semiconductor device includes a first transistor including a GaN-based semiconductor stacked structure formed over a substrate, a first gate electrode having a plurality of first fingers over the semiconductor stacked structure, a plurality of first drain electrodes provided along the first fingers, and a plurality of first source electrodes provided along the first fingers; a second transistor including the semiconductor stacked structure, a second gate electrode having a plurality of second fingers over the semiconductor stacked structure, the second drain electrodes provided along the second fingers, and a plurality of second source electrodes provided along the second fingers; a drain pad provided over or under the first drain electrodes, and coupled to the first drain electrodes; a source pad provided over or under the second source electrodes, and coupled to the second source electrodes; and a common pad coupled to the first source electrodes and the second drain electrodes.

Abstract: In a system for providing electrical energy for an electronic circuit adapted to supply power to a load, one terminal for a power supply voltage of the circuit is connected to a positive pole of an energy source, and one terminal for ground for the circuit is connected to a negative pole of the energy source via a rectifying electronic component, and a capacitor is connected between the two terminals of the circuit for partial supply of the circuit with electrical energy.

Abstract: An output driver circuit is provided. In accordance with various example embodiments, an output driver circuit includes a high-side driver circuit having transistors coupled in anti-series between a power source and an output node, and a low-side driver circuit having transistors coupled in anti-series between the output node and ground. For each transistor, a diode is connected between the source and drain of the transistor, with the diodes of the respective high-side and low-side circuits being arranged to prevent/mitigate the flow of current in opposite directions.

Abstract: Methods and apparatus provide for a primary side circuit including one or more voltage nodes; and a monitoring circuit operating to monitor one or more parameters of the primary side circuit, and including at least one sensing circuit and at least one processing circuit within a secondary side circuit, where the sensing circuit includes a resistor network having an input for receiving a first sensed voltage from a first of the voltage nodes of the primary side circuit, traversing an isolation boundary between the primary side circuit and the secondary side circuit while adhering to a safety specification, which includes a primary-secondary isolation requirement, and having an output for providing a first modified sensed voltage to the processing circuit.

Abstract: The disclosed embodiments relate to a power supply for a portable electronic device. This power supply includes a power source, an inductor, a control circuit, and an input switch that couples the input terminal of the inductor to either the power source or a reference voltage. The power supply also includes a first output path that produces a first output voltage and a second output path that produces a second output voltage. The first output path includes a first diode coupled between the output terminal of the inductor and the first output voltage, and a first output capacitor coupled between the first output voltage and the reference voltage. The second output path includes a second diode and an output switch coupled between the output terminal and the second output voltage, and a second output capacitor coupled between the second output voltage and the reference voltage.

Abstract: There is provided an AC/DC two-way switch connected between an AC power source or a DC power source and a load to control a power supply to the load. The AC/DC two-way switch includes: a bi-directional semiconductor switch element having a transistor structure connected in series between a power source and the load; a rectifying unit connected in parallel between the first input terminal and a second input terminal; a power source unit for converting an output voltage from the rectifying unit into a stable voltage; and a controller for controlling an entire operation of the AC/DC two-way switch. The AC/DC two-way switch further includes a driving unit for turning on the bi-directional semiconductor switch element in response to a control signal.

Abstract: A circuit for use in a half bridge converter includes a high side switch coupled between a positive input terminal and a first terminal of a primary transformer winding. A low side switch is coupled between a negative input terminal and the first terminal. A first control circuit is coupled to the high side switch to sense a slope of a voltage across the high side switch while the high side switch is off to control the high side switch in response to the sensed slope across the high side switch. A second control circuit is coupled to the low side switch to sense a slope of a voltage across the low side switch while the low side switch is off to control the low side switch in response to the sensed slope of the voltage across the low side switch.

Abstract: A power converter circuit includes a storage component, a rectifier component comprising a first field effect transistor and having first and second bias states, and a switch including a second field effect transistor having first and second operational states. The first and second field effect transistors are High Electron Mobility Transistors (HEMTs).

Abstract: Area-efficient voltage regulators are provided in which a first transistor has a first breakdown voltage and a first on-state resistance and a second transistor has a second breakdown voltage that exceeds the first breakdown voltage and a second on-state resistance that exceeds the first on-state resistance. With this arrangement, the second transistor can be biased to raise an output voltage. When the difference between an input voltage and the output voltage is less than a predetermined voltage, the second transistor is disabled and the first transistor is controlled to provide the output voltage at a wherein the controlling is preferably performed with a feedback control loop. The die area of the first transistor can be reduced because its on-state breakdown need only exceed the predetermined voltage rather than the substantially-higher input voltage.

Abstract: A method and system for controlling a plurality of output voltages.

Abstract: A multi-layer integrated circuit package includes a switched-mode power supply circuit including a plurality of transistors which form part of a main current loop of the switched-mode power supply circuit. The plurality of transistors are arranged in one or more layers of the integrated circuit package. The package further includes a conductive plate arranged in a different layer of the integrated circuit package than the plurality of transistors. The conductive plate is in close enough proximity to at least part of the main current loop so that a current can be electromagnetically induced in the conductive plate responsive to a change in current in the main current loop.

Abstract: An ultra-low current generator and a voltage regulator using such a generator. The generator includes a first set of Q transistors connected as a current mirror and able to be linked to a supply voltage; a second set of Q?1 transistors connected as a current mirror and each connected in series to one of the transistors in the first set of transistors; a first transistor connected in series with a transistor in the second set of transistors; and a second transistor, connected as a current mirror with the first transistor, and connected in series with a transistor included in the first set of transistors. The first transistor operates in its linear zone, a value of a current generated by the current generator depends on an equivalent resistance of the first transistor, and the first and second transistors have ultra-long channels, with a very large length/width ratio.

Abstract: Described herein are methods and circuits for driving a power switching device of a power converter. The methods and circuits include providing a negative gate to source voltage to the power switching device during an off transition of the power switching device, wherein the negative gate to source voltage is provided independent of one or more switching element for driving the power switching device; wherein body diode conduction by the one or more switching element is mitigated; wherein a circuit connected in parallel with the gate and source of the power switching device is used to set or define the negative gate to source voltage.

Abstract: The invention relates to a DC to DC voltage converter including a charge pump capacitor (C) installed parallel to a means (10, 20) for controlling switches (T1, T2), arranged to maintain a predefined voltage range on the terminals of the means (10) for controlling the upper switch (T1). The control means (10, 20) are arranged so as to close the lower switch (T2) in order to impose zero electric potential on the central terminal of the star (O) when the upper switch (T1) is open, in order to force the charging of the charge pump capacitor (C).

Abstract: According to one embodiment, a smart photovoltaic (PV) panel comprises a plurality of PV cell groups each including at least one PV cell. The smart PV panel also includes at least one serial boost combiner circuit (SBCC) configured to receive an output from the plurality of PV cell groups as inputs. Each SBCC comprises several boost blocks connected in parallel, each of the boost blocks including a switching device and a respective boost block output directly connected to an output node of the SBCC. In addition a corresponding power terminal of each of the switching devices is directly connected to a common ground node of the SBCC. In one embodiment, the smart PV panel also includes a power inverter coupled to the one or more SBCCs and a communication unit interfaced with a local controller.

Abstract: A snubber circuit for use with a DC/DC converter broadly comprises a snubber resistor connected in parallel with a snubber inductor. The DC/DC converter may include a voltage source, a first switching element, a second switching element, an output inductor, and an output capacitor. The voltage source may include a positive terminal and a negative terminal connected to a ground node. The first switching element may include a first terminal connected to the positive terminal of the voltage source The second switching element may be connected to a second terminal of the first switching element. The series combination of the output inductor and the output capacitor may be connected between the second terminal of the first switching element and the ground node. The snubber circuit may be connected between the second switching element and the ground node.

Abstract: A semiconductor integrated circuit includes a current mirror having a predetermined input-output ratio and including a first transistor configured to receive an input current and a second transistor configured to output an output current, and an output transistor configured to generate a reference voltage according to the output current of the current mirror. The value of the output current is greater than the value of the input current, and the total area of one or more collector regions of the first transistor is substantially the same as the total area of one or more collector regions of the second transistor.

Abstract: Methods and apparatus are provided for operation of a voltage source inverter. A method of operating a voltage source inverter having an output with multiple voltage phases having a DC voltage level, the method comprising sensing a low output frequency condition; determining a DC voltage offset responsive to the low output frequency condition; and applying the DC voltage offset when operating the voltage source inverter resulting in a change to the DC voltage level of the multiple voltage phases.

Abstract: Embodiments of signal bias generators and regulators are described generally herein. Other embodiments may be described and claimed.

Abstract: A self-oscillating switch circuit for amplitude modulation dimming for dimming a LED load. The self-oscillating switch circuit comprises a high-power input terminal (S2) for supplying a first power to the load and a low-power input terminal (S1) for supplying a second power to the load. The switch circuit further comprises a power switch semi-conductor device (Q1) configured for controlling a load current from at least one of the high-power input terminal (S2) and the low-power input terminal (S1) to the output terminal. A control semi-conductor device (Q2) is configured to control the power switch semi-conductor device (Q1) in response to a sensing voltage.