Abstract: This document discusses, among other things, a device for providing a DC output voltage, including a first output voltage and a second output voltage, from an input voltage. The device can include a first voltage regulator configured to provide the first output voltage when the input voltage is below a threshold voltage, and a charge pump configured to provide the second output voltage from the first output voltage in a two-state mode when the input voltage is below the threshold voltage, and to provide the first output voltage and the second output voltage in a three-state mode when the input voltage is above the threshold voltage.

Abstract: In some embodiments, a voltage regulator device may include a switched capacitor voltage regulator to receive an input voltage and to provide an output voltage to a load, and a control unit to receive information related to a desired output voltage for the switched capacitor voltage regulator and to determine a desired input voltage for the switched capacitor voltage regulator based on the desired output voltage and selected operation mode or modes of switched capacitor voltage regulator. Other embodiments are disclosed and claimed.

Abstract: An apparatus and method for extracting maximum power from a solar cell are provided. The apparatus includes a solar cell for producing power from solar energy, a maximum power extractor for generating a pulse width modulation signal for extracting the maximum power from the solar cell, and a DC-DC converter for adjusting an amount of current generated from the solar cell according to the pulse width modulation signal.

Abstract: Methods and systems for providing electrical power, including determining a plurality of fine power duty cycles according to a respective plurality of power values, and generating the respective plurality of power values using a time-shared pulse-width modulator (PWM), the time-shared PWM being configured to be modulated at the respective plurality of fine duty power cycles during a respective plurality of time slots.

Abstract: To equalize the intensity of light emitted by display elements on a display device, a plurality of current-drive circuits are connected in cascade through two terminals of each of the current-drive circuits, each comprising a reference current generation section including a reference resistor and a plurality of current drive sections. Reference current sunk by an external reference current source causes a voltage drop across the reference resistor, and the voltage drop is applied across a current adjustment resistor In response to an image signal, the current-drive circuit outputs current, determined by multiplying each of a plurality of internal reference currents by an optional factor and summing the resulting currents to the display elements. Since the magnitude of the internal reference current flowing inside the current-drive circuit can be varied by varying the value of the current adjustment resistor, gamma correction can be applied to drive current with high accuracy.

Abstract: An electronic device is provided comprising a driver for light emitting semiconductor devices. The driver includes a first MOS transistor (MN1) coupled with a channel to the light emitting semiconductor device at an output node. The first MOS transistor (MN1) is configured to determine a current through the light emitting semiconductor device (LED). A control loop is provided so as to control the first MOS transistor to maintain the magnitude of the current through the light emitting semiconductor device at a target value when a voltage drop across the first MOS transistor (MN1) changes. A second MOS transistor is coupled to the output node and biased so as to supply an auxiliary current to the output node, when the voltage drop across the first MOS transistor drops below a minimum voltage level and a feedback loop is provided to reduce the current through the light emitting semiconductor device by an amount proportional to the auxiliary current.

Abstract: A circuit for generating a voltage of a semiconductor memory apparatus includes a control unit that outputs a driving control signal in response to an enable signal and a burn-in signal, a first voltage generating unit that generates and outputs a first voltage in response to the enable signal, and a voltage maintaining unit that maintains the first voltage in response to the driving control signal.

Abstract: A DC-DC converter including a power supply supplying direct current (DC) to an inductor, a switching device controlling the supply of DC from the power supply to the inductor by switching between a conductive state and a disconnected state according to a modulation signal, a signal output device generating the modulation signal for increasing or decreasing a period of the conductive state of the switching device, wherein the signal output device increases or decreases a duty ratio of the modulation signal to increase or decrease the period of the conductive state of the switching device, and a delay device controlling an increase of a duty ratio of the modulation signal, wherein the signal output device outputs the modulation signal with the controlled duty ratio to the switching device, thereby delaying the switching device from reaching a conductive state in which the duty ratio is a value of 1.

Abstract: A method of controlling a multiphase power converter including a plurality of sub-converters coupled to provide power to a load is disclosed. Each sub-converter includes a power switch. The method includes selectively and consistently turning on the power switch of one or more of the sub-converters at substantially a same time as a reference signal representing a desired output of the power converter increases. The method further includes selectively and consistently turning off the power switch of one or more of the sub-converters at substantially a same time as the reference signal representing the desired output of the power converter decreases. Other methods, multiphase power converters and controllers for multiphase power converters are also disclosed.

Abstract: A voltage regulator for controlling a reference pulse-voltage comprising a sequence of positive-negative pulses which defines an active range and a dummy range is disclosed. The voltage regulator includes an acquisition unit adapted to receive each pulse of the reference pulse-voltage and determine whether an alteration of the pulse is needed according to a predetermined calculation, and generate a result message when it is determined that an alteration of the voltage pulse is needed, and a voltage control unit adapted to generate an output pulse-voltage corresponding to the reference pulse-voltage. When no result message is generated, the voltage control unit is configured to output an output pulse having the same polarity as that of the received pulse of the reference pulse-voltage, and when the result message is generated, the voltage control unit is configured to output an output pulse having an opposite polarity to that of the received pulse.

Abstract: In circuit board for a converter, including control electronics, the circuit board includes a device for current detection, the device respectively having at least two measuring amplifier circuits, only the output of one of the measuring amplifier circuits being supplied as the detected current value to the control electronics of the converter.

Abstract: A method includes selectively applying full cycles of AC power to a load. The cycles may have first and second states such as full on and full off states. The cycles may be arranged in groups in a pattern. The pattern may have a length that is shorter than a perceptible response time of the load. Different patterns may be used for different power levels.

Abstract: A high-voltage power supply to output a plus/minus high-voltage, which is applied to image forming apparatuses, includes a plus high-voltage output unit outputting the plus high-voltage by using a Pulse Width Modulation (PWM) signal, a minus high-voltage operation control unit charging a certain voltage while the plus high-voltage output unit is outputting the plus high-voltage, a minus high-voltage output unit outputting the minus high-voltage by using the certain voltage charged in the minus high-voltage operation control unit, and a minus high-voltage blocking unit to block the output of the minus high-voltage from the minus high-voltage output unit while the plus high-voltage output unit is outputting the plus high-voltage.

Abstract: Provided is a boosting circuit. The boosting circuit includes a voltage generator, a booster, a voltage detector, and a selector. The voltage generator receives an external first voltage to output a second voltage. The booster boosts an input voltage to output a third voltage. The voltage detector detects at least one voltage level of the first to third voltages to output a selection signal. The selector transfers one of the first and second voltages as the input voltage of the booster in response to the selection signal.

Abstract: A method of generating an output DC voltage of a gas discharge process voltage supply unit, in which in a first voltage transformation stage a first DC voltage is transformed into a second DC voltage of a predetermined voltage range, and the output DC voltage is generated from the second DC voltage in a second voltage transformation stage. A switching element of at least one boost converter is switched with a controlled pulse-duty factor for generating the output DC voltage in the second voltage transformation stage. This method permits striking and maintenance of a plasma process.

Abstract: A current control element (variable resistance element) is provided on a supply path of the current from a voltage regulator to another voltage regulator. An alarm driving circuit is provided on a branch flow path of the current from the voltage regulator to the voltage regulator. When the alarm driving circuit needs to be operated, a current control element controlling unit controls the resistance value of the current control element to branch the current flowing through the supply path to the branch flow path. In this case, the current branched to the branch flow path is set to the amount required to operate the alarm driving circuit. Since the sum of the currents is supplied to the voltage regulator and is the same as the current flowing before the alarm driving circuit is activated, there is no shortage of supplied power to a CPU.

Abstract: Valve positioning systems may include one or more components and a controller. Components may include one or more electric-to-pressure output converters, relays, gas supplies, and/or actuators. A controller may adjust a position of a valve by sending a signal. The valve positioning system may individually monitor components and determine the condition of each component being individually monitored. The valve positioning system may determine if a component will fail prior to failure and/or determine if a problem will occur in a component prior to the problem occurring.

Abstract: A Power Converter, a device, and a method for interleaving controlling Power Factor Correction (PFC) circuits are disclosed. The Power Converter includes a first bridge arm unit, a second bridge arm unit, and a capacitor. The upper side of the first bridge arm unit and the upper side of the second bridge arm unit are connected with the first end of the capacitor, and the lower side of the first bridge arm unit and the lower side of the second bridge arm unit are connected with the second end of the capacitor. The first bridge arm unit includes two diodes or switches series-connected in the same direction, and the joint of the two diodes or switches is connected with the first end of the power supply. The second bridge arm unit includes two switches series-connected in the same direction and one inductor, and the first end of the inductor is connected with the joint of the two switches, while the second end of the inductor is connected with the second end of the power supply.

Abstract: Electronic leakage reduction techniques are provided, whereby an electrical outlet with a programmable computing unit is programmed to detect the current, resistance, power or pattern of current, resistance or power of an attached appliance in the on position and/or off position. Among other aspects, the electrical outlet with a programmable computing unit delivers a selected voltage below the original operational voltage and/or delivers voltage at particular durations for particular intervals to the appliance in the off position and compares detected current, resistance, power or pattern of current, resistance or power to programmed levels associated with the appliance in the on position and/or off position. If any or some of those characteristics match those programmed associated with the appliance in the on position, or fail to match those programmed associated with the off position by a set confidence interval, original operational voltage is provided to the appliance.

Abstract: The present invention proposes a hot surface igniter (HSI) controller which is transformerless and which is capable of delivering power from a 120/240 VAC RMS mains voltage, for example, to a load whose nominal operational voltage is equivalent to 24 VAC RMS, for example, sinusoidal full wave AC Voltage. The controller provides an impulse range which is mainly designed to deliver power to hot surface igniter active loads with sufficient thermionic inertia and mass, and where the real voltage shape of supplied power is unimportant. This is achieved by supplying half-cycle pulses to the HIS that are separated by even number of half-cycles that are not supplied to the HIS. Thus the consecutively applied half-cycles are always of opposing polarity.

Abstract: The invention relates to a power supply device for an RF transmitter (5), the device comprising at least one battery (2) and at least one capacitor (3) electrically connected in parallel between the battery (2) and the RF transmitter (5), and voltage-raising means (4?) for charging the capacitor (3) to a storage voltage (VC) higher than the voltage delivered by the battery during an initial charging stage, the voltage-raising means (4?) comprising an inductor (L) and a diode (D) in series, and associated with a switch (40?) suitable, during the storage stage, for periodically causing energy to be accumulated in the inductor (L) followed by transferring the accumulated energy into the capacitor (3).

Abstract: A multilayer inductor comprising a coil embedded in a magnetic portion, and a magnetic gap formed by a non-magnetic portion in part of a magnetic path, the magnetic portion being made of Ni ferrite, whose relative temperature coefficient ??ir of initial permeability at a frequency of 1 MHz is more than +10 ppm/° C. and +40 ppm/° C. or less between ?40° C. and +80° C., the non-magnetic portion being made of Zn ferrite containing more Zn than in the magnetic portion and having a Curie temperature Tc of ?50° C. or lower, and the Zn content changing continuously in boundary regions between the non-magnetic portion and the magnetic portion, whereby the thickness of the magnetic gap changes with the temperature.

Abstract: The present invention provides a device and a method for controlling a DC bias of a RF discharge system. Said device comprises a DC bias detection module (302), a mode selection module (301), a DC bias controlling module (303) and a RF power providing module (304). The mode selection module (301) receives a parameter and a type of the parameter. If the type of the parameter is representative of voltage, the DC bias controlling module (303) calculates a power value according to the voltage-related representative parameter and the detected DC bias value, and the RF power providing module (304) provides power according to the calculated power value. If the type of the parameter is representative of power, the RF power providing module (304) provides power according to the power-related representative parameter.

Abstract: An oscillation frequency control circuit controls a second oscillation circuit, which generates and outputs a second clock signal of a second frequency according to a received control signal, to control the second frequency. The oscillation frequency control circuit includes a frequency difference detection circuit unit configured to detect a difference between a predetermined first frequency of a first clock signal generated by an external first oscillation circuit and the second frequency, and generate and output an output signal indicating a detection result, and a frequency control circuit unit configured to control, according to the output signal of the frequency difference detection circuit unit, the second oscillation circuit to control the second frequency of the second clock signal to make an absolute value of the difference between the first frequency and the second frequency greater than a predetermined value.

Abstract: A power consumption control method applied to a communication system adjusts the power consumption of a portion of circuit in the communication system according to a transmission distance between the communication system and another communication system. Another power consumption control method applied to a communication system adjusts the power consumption of a portion of circuit in the communication system according to a signal index of the communication system.

Abstract: A limitation of the interaction between cascaded tap changers and/or between a tap changer and a shunt compensator independently of any real-time communication between the respective controllers is disclosed. Coordinated voltage control in distribution networks can be achieved by an adaptive updating or tuning of control parameters DB4, TD4 of a voltage control unit controlling a second voltage control device, depending on instantaneous or actual operating conditions evaluated by the voltage control unit itself. Instead of using constant control parameters initially set by a commissioning engineer, the parameters are updated based on a voltage level UP4, which in turn is responsive to or affected by any control action performed by a first voltage control device neighboring the second voltage control device.

Abstract: To accurately regulate output of a high-frequency power with a simple configuration. A high-frequency power supply circuit includes: a basic drive square wave generation circuit unit (5) for generating a basic drive square wave having an output frequency; a differential signal generation circuit unit (9) for generating a front edge differential signal of the basic drive square wave; a vibrator circuit unit (15) having a square wave signal generator (10) for outputting a square wave signal having a signal width within a period corresponding to a half cycle of the output frequency upon input of a trigger signal from outside and signal width control circuits (11, 12) varying/controlling the signal width of the square wave signal according to the control signal; and a switching amplification circuit unit (6) for amplifying the amplification source signal based on the output signal from the vibrator circuit unit (15).

Abstract: The invention relates to an autarkic field device or an autarkic radio adapter (2) for a field device (1), of automation technology fed with limited energy via an energy supply unit (3) associated, or associable, with the field device (1) or the radio adapter (2), characterized in that, between the energy supply unit (3) and an internal voltage source (4), whose voltage exceeds, or at times can exceed, the voltage of the energy supply unit (3), a barrier (5a; 5b) of at least one diode group having at least two diodes (6) connected in parallel is arranged, which blocks flow of electrical current from the internal voltage source (4) to the energy supply unit (3) or to the connection terminals (7) of the field device (1) or of the radio adapter (2) for the energy supply unit (3).

Abstract: A voltage regulating power supply includes: a switching regulator powered by a supply voltage level, the switching regulator for generating a first output voltage in accordance to a first reference voltage; and a linear regulator coupled to the first output voltage, the linear regulator for generating a second output voltage in accordance to a second reference voltage; wherein a noise sensitive circuit draws power from the second output voltage.

Abstract: A system and method that analyzes at least one aspect of the power grid for demand response in order to reduce feeder circuit losses is provided. The system and method may use a demand response model to select one or more factors for the demand response, such as selecting a subset of customers for demand response from a larger pool of available demand response customers. The demand response model may include a grid structure component, such as an indication of the particular customer's position in the grid and a dynamic operation component, such as a real-time measurement of current in the feeder circuit. By using the demand response model, feeder circuit losses may thereby reduced.

Abstract: A power supply apparatus of the present invention comprises: a constant voltage generation section (first DAC (21), second DAC (22), resistor (R2), resistor (R3)) that generates a positive constant voltage (Va); a pulse voltage generation section (pulse oscillator (23), amplifier (24)) that generates a positive pulse voltage (Vb); a capacitor (C1) of which one end is connected to the output terminal of the pulse voltage generation section; and a diode (D1) of which an anode is connected to the other end of the capacitor (C1), and of which a cathode is connected to the output terminal of the constant voltage generation section. A positive-negative bipolar pulse voltage (Vc) is outputted from the other end of the capacitor (C1). Thus, it is possible to generate a positive-negative bipolar pulse voltage with a simple and small-scale circuit configuration.

Abstract: A system for managing consumption of power supplied by an electric utility to power consuming devices includes at least one client device and a server. Each client device operates at least partially responsive to control messages received from the server and controls operation of one or more controllable devices. Each controllable device selectively enables and disables a flow of power to one or more of the consuming devices. The server stores information, on a per client device basis, relating to power consumed by the consuming devices. When a power reduction is requested by the utility, the server selects, based on client device information stored in the database, at least one client device to which to issue a power reduction message that indicates at least one of an amount of power to be reduced and an identification of a controllable device to be instructed to disable a flow of power.

Abstract: A system drives one or plurality of LEDs regulating their brightness by controlling LEDs average current or voltage. The system includes a switching power converter and an integrated digital regulator with at least one of electrical, thermal and optical feedbacks. The regulator is constructed as a hysteretic peak current mode controller for continuous mode of operation of the power converter. For discontinuous mode of operation of the power converter a pulse averaging sliding mode control is being used. Average LED current is measured by integrating LED pulse current at off time and hysteretically adjusting on time of the power switch. Input battery is protected from discharging at abnormally low impedance of the output.

Abstract: Certain embodiments of a method and system for safe and efficient power down and drawing minimal current when a device is not enabled may comprise receiving within a network adapter chip (NAC) a signal that indicates a reduced power mode. Based on this signal, the NAC may control an off-chip voltage source that provides reduced voltage to circuitry within the NAC. The off-chip voltage source, which may comprise a first PNP transistor and a second PNP transistor, may reduce a voltage to a first voltage and a second voltage. The NAC may also reduce current through the off-chip voltage source to approximately zero amperes and an output voltage of the off-chip voltage source to approximately zero volts. The first voltage and/or the second voltage may be fed back to control the output voltage and current of the off-chip voltage source.

Abstract: DC-DC converters are described that employ a time-averaged modulated bypass diode to facilitate the efficient harvest of power in photovoltaic systems.

Abstract: A constant-current circuit includes a first transistor for supplying a current based on a control signal input to a gate of the first transistor so as to serve as a current source, a second transistor for supplying a current to a load based on the control signal input to a gate of the second transistor, a voltage regulation unit for controlling a drain voltage of the first transistor according to a drain voltage of the second transistor, a current detector for detecting a value of a current flowing through the first transistor and output a current according to the detected value, and a controller for controlling each gate voltage of the first and second transistors according to the value detected by the current detector so that the current flowing through the first transistor becomes a predetermined value. The first and second transistors are MOS transistors having the same conductivity.

Abstract: A system and method for using a physical layer device's discovery of cable shielding for PoE current capacity setting and temperature de-rating. Headroom in a particular cable installation is increased when it is determined that the physical layer device is coupled to a shielded cable, which more effectively removes heat from a bundled cable. By the determination of the type of cabling, the current capable of being carried over the cable can be increased and/or the temperature de-rating decreased due to the removal of limitations of worst-case cable assumptions.

Abstract: Supply circuit (3) for an electric apparatus (1) having a positive supply line (5) and a negative supply line, to which lines a polarity inversion detection module (18), an inrush current module (18) and a capacitive filter element (14) are connected, wherein the capacitive filter element is mounted on a secondary line (15), the ends of which are connected to the positive and negative line, respectively; the circuit comprising a first MOSFET transistor (16) channel N and a second MOSFET transistor (17) channel N mounted in series on the positive line, wherein the first transistor has a gate which is connected to the inrush current detection module and the second transistor has a drain which is connected to the positive line prior to the point of connection between the positive line and the secondary line and a gate which is connected to the polarity inversion detection module.

Abstract: A dedicated power supply apparatus includes a regulator that receives power from an external power source, two signal lines to which the regulator is connected, and two resistors, each placed between the regulator and an associated one of the two signal lines.

Abstract: A power supply for IGBT/FET drivers (1) that provides separated, isolated power to each IGBT/FET driver in a system wherein the power supply (1) is connected to at least one voltage controller (16) having at least one line in main power connector (14), at least one line out main power connector (15) and at least one drive signal command input (11) for connection to at least one IGBT/FET driver. The power supply (1) includes at least one power supply unit (5) in connection with at least voltage controller (16), at least one diode (2) for routing a predetermined amount of power from the at least one voltage controller (16) to at least one capacitor (3) and at least one capacitor (3) for routing said predetermined amount of power from said at least one diode (2) to said at least one voltage controller (16).

Abstract: Circuits and methods for paralleling voltage regulators are provided. Improved current sharing and regulation characteristics are obtained by coupling control terminals of the voltage regulators together which results in precise output voltages and proportional current production. Distributing current generation among multiple paralleled voltage regulators improves heat dissipation and thereby reduces the likelihood that the current produced by the voltage regulators will be temperature limited.

Abstract: A switching power converter includes an input terminal for receiving an input voltage, an output terminal for supplying an output voltage, a coupled choke having a main winding and an auxiliary winding, an output capacitor coupled to the output terminal, a main diode coupled between the auxiliary winding and the output terminal, and a switch having first and second positions. The main and auxiliary windings are connected to be charged by an input voltage when the input voltage is coupled to the input terminal and the switch is in the first position. The auxiliary winding is connected to reverse bias the main diode when the switch is switched from the first position to the second position to thereby suppress reverse recovery current in the main diode. The power converter may further include an auxiliary diode coupled between a common node of the main and auxiliary windings and the output terminal, as well as an inductor in series with the auxiliary diode.

Abstract: A regulator includes a power-converting circuit and a protection circuit. The power-converting circuit is for converting a primary voltage to a secondary voltage. The protection circuit is coupled to the power-converting circuit. The protection circuit receives the primary voltage earlier than the power-converting circuit. When a voltage spike of the primary voltage occurs, the protection circuit shunts the high instantaneous voltage to ground. An electrical device and a car using the regulator is also provided.

Abstract: A voltage regulator includes an input terminal for receiving a power input having a first voltage level, and an output terminal for generating a power output. A reference signal having a second voltage level is derived from the first voltage level adjusted with a predetermined offset value for controlling the power output to be at a third voltage level proportional to the second voltage level.

Abstract: A power supply controller having final test and trim circuitry. In one embodiment, a power supply controller for switched mode power supply includes a selector circuit, a trim circuit, a shutdown circuit and a disable circuit. The trim circuit includes a programmable circuit connection that can be selected by the selector circuit by toggling a voltage on an external terminal such as for example a power supply terminal, a control terminal or a function terminal of the power supply controller. The programmable circuit connection in the trim circuit can be programmed by applying a programming voltage to the external terminal. The shutdown circuit shuts down the power supply controller if the temperature rises above an over temperature threshold voltage. The shutdown circuit includes adjustment circuitry that can be used to test the shutdown circuit. The adjustment circuitry can adjust and reduce the over temperature threshold of the power supply controller.

Abstract: Provided is a voltage regulation system using an abrupt metal-insulator transition (MIT), which can regulate various zener voltages and can be easily manufactured. The voltage regulation system includes: an input power source: a series resistor connected in series to the input power source; and an MIT insulator connected in series to the series resistor, and undergoing an abrupt MIT such that the range of an output voltage regulated to be kept constant varies according to the resistance of the series resistor.

Abstract: An electric power converter facilitates performing soft switching in the two-way electric-power-conversion operation thereof, and reducing the manufacturing costs thereof and the losses caused therein, The electric power converter includes a first switching device; a second switching device; a first series circuit including capacitor, a diode, the primary winding of transformer, and a third switching device; a second series circuit including a capacitor, a fourth switching device, the primary winding of transformer, and a diode; a third series circuit including a diode and the secondary winding of transformer; and a voltage clamping element connected in parallel to the primary winding of transformer. The first series circuit is connected in parallel to the first switching device, and the second series circuit is connected in parallel to second switching device. The third series circuit is connected between the DC output terminals.

Abstract: In a process for operating an air-cooled mains supply unit for industrial application, temperatures influenced by outer heat sources and by heat sources arranged in the mains supply unit are measured by thermo-elements and reported to a control system. Temperatures measured by at least two thermo-elements arranged at different measurement points are reported to the control system, and the measured temperatures are compared with temperature patterns. The comparison with known temperature patterns makes it possible to sense the totality of the thermal conditions continuously and to derive therefrom ratings for the control system.

Abstract: [Problems] To accurately regulate output of a high-frequency power with a simple configuration. [Means for Solving Problems] A high-frequency power supply circuit includes: a basic drive square wave generation circuit unit (5) for generating a basic drive square wave having an output frequency; a differential signal generation circuit unit (9) for generating a front edge differential signal of the basic drive square wave; a vibrator circuit unit (15) having a square wave signal generator (10) for outputting a square wave signal having a signal width within a period corresponding to a half cycle of the output frequency upon input of a trigger signal from outside and signal width control circuits (11, 12) varying/controlling the signal width of the square wave signal according to the control signal; and a switching amplification circuit unit (6) for amplifying the amplification source signal based on the output signal from the vibrator circuit unit (15).

Abstract: A DC converter and a mode-switching method used in an electronic apparatus are included. The electronic apparatus includes a subsystem circuit. The DC power converter comprises a first voltage converting circuit electrically connected to the subsystem circuit, receiving a system voltage and a first reference voltage, and converting the system voltage to a first output voltage based on the first reference voltage; and a second voltage converting circuit electrically connected to the subsystem circuit and receiving the system voltage and a second reference voltage, and converting the system voltage to a second output voltage to the same output end of the first voltage converting circuit based on the second reference voltage; wherein the second voltage converting circuit outputs the second output voltage to the subsystem circuit when the first output voltage at the output end is smaller than a threshold.