Abstract: A two-step charger includes an AC/DC power supply, a transformer, a compensator, a controller, a comparator and an isolating controller. The comparator detects whether a battery is connected to the transformer. If so, a command voltage of the charger is set at a high level. Since the battery voltage is lower than the command voltage, the controller orders the compensator to send out a compensating current. The current entering the primary side of the transformer is increased to promote the output current from the secondary side of the transformer. Once the comparator detects that the battery reaches as high as the charger, the command voltage is adjusted to a low level. The controller orders the compensator to stop outputting the compensating current. Therefore, a larger current can speed up battery charging. Once the battery is fully charged, the charging voltage is lowered to avoid high temperature.

Abstract: A method and apparatus for adaptively configuring an array of voltage transformation modules is disclosed. The aggregate voltage transformation ratio of the adaptive array is adjusted to digitally regulate the output voltage for a wide range of input voltages. An integrated adaptive array having a plurality of input cells, a plurality of output cells, or a plurality of both is also disclosed. The input and output cells may be adaptively configured to provide an adjustable transformer turns ratio for the adaptive array or in the case of an integrated VTM, an adjustable voltage transformation ratio for the integrated VTM. A controller is used to configure the cells and provide digital regulation of the output. A converter having input cells configured as a complementary pair, which are switched out of phase, reduces common mode current and noise. Series connected input cells are used for reducing primary switch voltage ratings in a converter and enabling increased operating frequency or efficiency.

Abstract: A DC-DC converter system having a DC-DC converter including a power transistor and a control unit is provided, which control unit provides control signals for triggering the power transistor. The DC-DC converter is operable in two operating modes: in a first operating mode, the DC-DC converter operates at high efficiency; and in a second operating mode, the DC-DC converter operates at low efficiency. The high power loss released in the second operating mode is used in the warm-up phase after the start of a motor vehicle engine as an additional heating system.

Abstract: An apparatus for generating an internal voltage includes an output-voltage detecting unit for detecting a voltage level of an internal voltage, an oscillating unit for generating a periodic signal in response to a detection signal from the output-voltage level detecting unit, a first driving-voltage level detecting unit for detecting an increase of a voltage level of a driving voltage, a second driving-voltage level detecting unit for detecting a decrease of a voltage level of the driving voltage, a period control unit for controlling a period of the periodic signal in response to output signals of the first and second driving-voltage level detecting units, and a charge pumping unit for generating the internal voltage by charge-pumping the driving voltage in response to an output signal from the period control unit.

Abstract: A power supply circuit and a method for adjusting an output voltage therein are provided. The power supply circuit includes a regulator having an input terminal receiving an input voltage, an output terminal outputting an output voltage and a regulating terminal, a voltage divider coupled between the output terminal and a ground, generating a dividing voltage, and a gain circuit coupled between the regulating terminal and the voltage divider, receiving the dividing voltage and generating a gain for adjusting the output voltage according to a reference voltage.

Abstract: A DC power conversion circuit having self-auxiliary power and self-protection against a short or open load circuit includes a DC voltage source, a driving circuit, and an auxiliary circuit. The DC voltage source is used for providing a DC power. The driving circuit includes a switch, a first resistor, a control signal generator, a second resistor, a diode and an inductor. The switch is used for conducting or cutting off an electrical connection according to an incoming control signal. The control signal generator senses voltage of the first resistor to generate the control signal. The inductor is coupled between the first resistor and a load circuit. The auxiliary circuit is parallel to the inductor and includes an auxiliary capacitor and an auxiliary diode. The auxiliary capacitor is coupled between the first resistor and the second resistor. The auxiliary diode is coupled between the inductor and the auxiliary capacitor.

Abstract: Disclosed is a transdermal electrotransport drug delivery system having a constant current that can accommodate large resistance change in a body surface. A semiconductor circuit component such as a Zener diode or a PMOS FET is used to impose a voltage drop from the output of a voltage booster circuit to maintain a constant current for electrotransport. Methods for its use are also disclosed.

Abstract: A switched linear regulator includes a control device with a controlled current path and a control electrode. The current path is connected in series with a source of voltage and a load. An error signal generator compares the load voltage with a reference value to generate a degenerative error signal. The error signal is coupled to the control electrode with a voltage offset. An OFF control signal source includes a transistor which is connected to the control electrode to swamp or overpower the error signal, and render the controlled current path nonconductive. Thus, the same active control element both linearly regulates and provides an ON-OFF function. A speed-up transistor responds to the OFF signal to short the control electrode to a reference voltage to quickly discharge capacitance at the control electrode.

Abstract: A system and method are provided for using a class H amplifier in a tester for testing protective relaying equipment, particularly useful in conducting end to end testing. The class H amplifier is configured to provide separation between the amplifier and the power supply of the tester using a DSP which also offers flexibility for programming algorithms to realize efficiencies in matching the waveform to the output rail. End to end testing is also improved by including expected results for the test case used by the tester to enable the tester to determine how close the results are to what is expected. This offers time savings and is less prone to error in that the expected results can be predetermined by a qualified/experienced professional.

Abstract: A method of providing threshold voltage monitoring and control in synchronous power converters is disclosed. The method establishes a threshold voltage level for at least one of an upper gate and a lower gate power switch in a synchronous power converter. The threshold voltage levels indicate switching delay times are present in the upper and lower gate power switches. The method detects body diode conduction levels for both the upper and lower gate power switches. When at least one of the detected body diode conduction levels exceed a prescribed body diode conduction level, the method adjusts the threshold voltage level for at least one of the upper and lower gate power switches to reduce a body diode conduction time for the at least one of the upper and lower gate power switches.

Abstract: A radiation tolerant high-power DC/DC converter is disclosed. The converter does not incorporate radiation-hardened parts, but instead uses p-channel FET switches that have a negative gate threshold voltage. With exposure to radiation, the gate threshold voltage decreases, becoming more negative. Thus, the gate is still controllable.

Abstract: A voltage regulation system is provided including detecting a feedback voltage less than a reference voltage; asserting a current source gate output by the feedback voltage less than the reference voltage; activating a gated current source by the current source gate output; and waiting a delay interval before negating the current source gate output for turning off the gated current source.

Abstract: The speaker apparatus according to the invention is arranged in a manner that when the magnitude of an audio signal Sin increases temporarily and so a consumption power increases, a DC-DC converter reduces an output voltage Vout to thereby increase an output current Iout and further discharges a capacitor to thereby increase a current supplied to an amplifier. Thus, a power of 2.5 W or more supplied from a USB connection terminal can be temporarily supplied to the amplifier.

Abstract: The present invention is directed to a digital controller for adjusting the duty ratio a pulse width modulation control signal used to control a power switch of a switch mode power converter. According to various embodiments, the digital controller comprises a voltage compensator module for generating a first signal (Dvoltage) representative of the duty ratio of the control signal based on a difference between an output voltage of the converter and a reference voltage. The controller also includes a current compensator module for generating a second signal (Dcorrection) representative of a modification to the duty ratio of the control signal based on an output current of the converter. A subtraction module subtracts the second signal (Dcorrection) from the first signal (Dvoltage) to thereby generate a third signal (D), which is used by a duty ratio PWM generator module to generate the pulse width modulation control signal with the appropriate duty ratio.

Abstract: This device is A Specially Improved Automotive Replacement Voltage Regulator for use in the automotive components remanufacturing and original equipment alternator product. Particularly this device has additional transient suppression means for the loads; “high side drive” of the rotor field to eliminate corrosion from the low side short condition; full passivation around the monolithic chip; and a monolithic chip that contains both the power and control devices which permits a simplified heat sink for thermal dissipation.

Abstract: A current sensor senses the current at a sense transistor and generates an output current that is an accurate proportional representation of the current at the sense transistor. Furthermore, the sensed current is relatively independent of the resistive load of the feedback path at feedback control module to which it is applied. In one embodiment, the feedback control module uses the sensed current in a DC-DC voltage converter to regulate a voltage. The current sensor employs a pair of operational amplifiers to match a voltage at a current electrode of a transistor that generates the output current to a voltage at a current electrode of the sense transistor, such that an effective resistance of the transistor generating the output current is significantly higher than the resistive load of the feedback control module, thereby ensuring that the output current is relatively independent of the resistive load of the feedback control module.

Abstract: A voltage regulating circuit for providing a regulated output voltage. The voltage regulating circuit includes a voltage regulator, a converting circuit, a capacitive device, a first current mirror module, and a second current mirror module. The voltage regulator has a first output producing the regulated output voltage and a second output producing a pass voltage. The converting circuit converts the pass voltage into a first current and a second current passing through a first converting node and a second converting node respectively, where the first current charges/discharges the capacitive device. The first current mirror module has a first current mirror path coupled to the first converting node and a second current mirror path coupled to the second converting node. The second current mirror module has a first current mirror path coupled to the second converting node and a second current mirror path coupled to the first output.

Abstract: A sleep mode control circuit and method are provided to pull high the error signal of a DC/DC switching power supply system to a target level when the switching power supply system is in a sleep mode, such that the switching power supply system can be more rapidly waked up from the sleep mode to its normal mode once the loading of the switching power supply system increases. A threshold is given for the output signal of the comparator that is used to determine the duty for the switching power supply system, and the error signal in the sleep mode is thus maintained slightly lower than the minimum voltage for the error signal in the normal mode.

Abstract: A power supply apparatus and method of regulating is provided. A converter circuit includes a primary switching element and an auxiliary switching element. The auxiliary switching element is for transferring a reflected voltage signal. A transformer includes a primary and a secondary, the primary is coupled with the converter circuit. The primary and secondary each include a single winding. An output rectifier circuit is coupled with the secondary of the transformer. A resonant circuit is included in the converter circuit and is coupled with the primary. The resonant circuit includes one or more resonance capacitors that are configured for providing a transformer resonance. The transformer resonance comprises the reflected voltage signal, the capacitance of the one or more resonance capacitors and a parasitic capacitance of the transformer. The reflected voltage signal is reflected from the secondary to the primary.

Abstract: To provide a voltage supplying device and an image display device, which can bring a voltage on a line to be supplied with voltage (e.g. source line) to a substantially desired voltage. A voltage supplying device comprising a source line (L12), a source line (L13) adjacent to the source line (L12), and a voltage generating means for generating a voltage supplied to the source line (L12) and a voltage supplied to the source line (L13), wherein the voltage generating means receives a pixel data (D12) representing a driving voltage (v12) for on the source line (L12) and a pixel data (D13) representing a driving voltage (v13) for on the source line (L13), and generates a correction voltage (v12-?v3) different from the driving voltage (v12) using the received pixel data (D12) and (D13), and wherein the voltage supplying device supplies the source line (L12) with the correction voltage (v12-?v3).

Abstract: A series regulator, which includes a power adjusting portion to which power is supplied, the power adjusting portion making an adjustment to the power thus supplied and outputting the power thus adjusted to a load, and an adjustment control portion detecting an output voltage that is a voltage outputted to the load and controlling the adjustment based on the detection result, is provided with: a current detecting portion for detecting an output current that is a current outputted to the load; and a power supplying section for supplying the power to the power adjusting portion after changing a voltage according to the detection result of the current detecting portion. With this configuration, even when the magnitude of the output current varies, it is possible to appropriately adjust the input voltage according to the variations in the output current.

Abstract: A variable gain amplifier includes first and second power supply terminals arranged to be connected to a power supply, a transconductance amplifier, first and second PN junction elements, a voltage drop element, first and second resistors, a current-generating transistor, and a current mirror. The transconductance amplifier outputs a current corresponding to a difference between a potential of a base of the first initial stage transistor and a potential of a base of the second initial stage transistor. An emitter of the second initial stage transistor is connected to the emitter of the first initial stage transistor at a node. Each of the first and second PN junction elements has a first end connected to the base of the first initial stage transistor and a second end. The voltage drop element is connected between the second end of the first PN junction element and the first power supply terminal.

Abstract: Example embodiments relate to an internal power supply voltage generating device. The internal power supply voltage generating device may include a start-up voltage generating part, a reference voltage generating part, and/or an internal power supply voltage generating part. The start-up voltage generating part may be configured to generate a start-up voltage using an external power supply voltage. The reference voltage generating part may be configured to generate a reference voltage using the start-up voltage. The internal power supply voltage generating part may be configured to generate an internal power supply voltage using the reference voltage and the external power supply voltage. The start-up voltage generating part may be turned off by the reference voltage generated by the reference voltage generating part. Example embodiments also relate to a method of generating an internal power supply voltage.

Abstract: A method and apparatus for adaptively configuring an array of voltage transformation modules is disclosed. The aggregate voltage transformation ratio of the adaptive array is adjusted to digitally regulate the output voltage for a wide range of input voltages. An integrated adaptive array having a plurality of input cells, a plurality of output cells, or a plurality of both is also disclosed. The input and output cells may be adaptively configured to provide an adjustable transformer turns ratio for the adaptive array or in the case of an integrated VTM, an adjustable voltage transformation ratio for the integrated VTM. A controller is used to configure the cells and provide digital regulation of the output. A converter having input cells configured as a complementary pair, which are switched out of phase, reduces common mode current and noise. Series connected input cells are used for reducing primary switch voltage ratings in a converter and enabling increased operating frequency or efficiency.

Abstract: A regulated voltage is generated at an output terminal of a voltage regulator circuit having at least one input terminal. A feedback signal is coupled from a first transistor coupled in parallel with a first resistor between the output terminal and the input terminal. The feedback signal is coupled to the input terminal to regulate the stability of the voltage regulator circuit. In a method of operation, the stability of a circuit is regulated by generating a feedback signal in the circuit to add a zero to a transfer function and raise an open loop phase curve of the circuit to result in a better power signal rejection ratio over a frequency range for the circuit.

Abstract: An exemplary power supply control circuit (200) includes a first port (201), a second port (202), a third port (203), a controllable switch (280), and a control circuit (270). The first and second ports are configured to receive a power supply voltage signal. The second and third ports are configured to output the power supply voltage signal to a load circuit. The controllable switch includes a control member (281) and a switch member (282 ). The control circuit is configured to control a working state of the control member. When the load circuit stops working, the control circuit controls the control member to control the switch member to be disconnected, so as to cut off the power supply voltage signal from outputting to the load circuit. A liquid crystal display (400) using the power supply control circuit is also provided.

Abstract: A pulse width modulation (PWM) circuit and a method for enabling the same are provided. The method includes the steps of: receiving a first power voltage and a second power voltage; providing a high-side driving power pin, wherein the peripheral circuit of the high-side driving power pin is adapted for generating a high-side driving voltage according to the first power voltage and the second power voltage; and enabling the PWM circuit when the high-side driving voltage is larger than the second power voltage.

Abstract: A communication card including a card substrate, a power interface adapted to receive power from a power source and distribute it to elements mounted on the card substrate and a ground start detection circuit on the card substrate. The card additionally includes an active current regulating circuit adapted to receive electrical power through the power interface, regulate a provided current responsive to the received electrical power and provide the regulated current to the ground start detection circuit.

Abstract: Analog voltage drain with reduced current drain is achieved by a a new capacitive-divided feedback architecture. During the operational phase an op amp monitors a capacitively-divided fraction of the output voltage, and drives a current sink or source accordingly; during an initial phase the output is forced to the correct value by a different circuit, while the opamp is connected to self-tune itself in a way which removes DC offset effects.

Abstract: A voltage control circuit is provided. The voltage control circuit comprises a control voltage source, a current generating unit, and an output voltage generating unit. The control voltage source inputs a single end control voltage. The current generating unit coupled to the control voltage source and a ground generates a first current according to the single end control voltage. The output voltage generating unit coupled to the current generating unit, receives a reference voltage, and generates a first output voltage and a second output voltage according to the first current and the reference voltage. A value of the first output voltage is greater than a value of the second output voltage.

Abstract: The voltage applied to an integrated circuit is controlled by a temporal process monitor formed as part of the integrated circuit. The temporal process monitor includes a voltage controlled oscillator for producing a first output signal having a first period. A comparator compares the first period to one or more reference values. Should the first period be greater than a first selected reference value the comparator sends a signal to increase the voltage being supplied to the integrated circuit. Should the first period be less than a second selected reference value, the comparator sends a signal to decrease the voltage applied to the integrated circuit. In some embodiments a scaling circuit is provided for producing a second output signal having a second period different from (typically but not necessarily longer than) the first period.

Abstract: An apparatus and method for initiation and control of a sustained metal plasma and nano plasma (macroparticulate) deposition methods for preparing modified metal coatings are provided. The plasma deposition process can be tightly controlled by virtue of a device that incorporates a plasma arc initiator component and an internal power supply that is capable of controlling dwell time on the target and the size range of particles ejected in the plasma arc.

Abstract: Devices, such as mobile devices, may be exposed to short circuit and output overload events. To protect against such events, mobile devices typically include current limit circuits. Some current limit circuits may involve user programmable function. User programmable function may need accurate current limit detectors. Various embodiments of the present invention include devices and methods for detecting one or more programmed current limits. Some embodiments allow for a user application to select among parallel or serial configurations of current detection circuitry. Each such configuration may include multiple resistive devices of different resistive values.

Abstract: A circuit arrangement for voltage regulation including a first transistor coupled between a first node and a third node, a second transistor coupled between a second node and the third node, a third transistor coupled between the third node and an output node, and a control unit that can be coupled to the first transistor, that can be coupled to the second transistor, and is coupled to the third transistor, wherein the control unit is configured to steer the transistors such that a predetermined output voltage is provided at the output node when a supply voltage is provided at one of the first node and the second node.

Abstract: The invention relates to a current regulator having the following features: a first semiconductor body (1; 1?) having a first and second terminal contact (11, 12), a transistor (T) having a control terminal and a load path, which is integrated in the semiconductor body (1; 1?) and the load path of which runs between the terminal contacts (11, 12) of the semiconductor body, a current measuring resistor (22), which is at least partly formed by a section of the load path of the transistor, an evaluation and drive circuit (3), which is connected to the current measuring resistor (22) and which is designed to drive the transistor depending on a voltage across the measuring resistor (22).

Abstract: An improved power supply unit includes a DC power source having a positive terminal and a negative terminal, and a voltage regulating circuit that includes a plurality of elements coupled in series between the positive and negative terminals of the DC power source to regulate the power supply signals supplied thereto to effectively cancel ripple and noise in such power supply signals. In one embodiment, the series-coupled elements include at least one resistor and a transconductive element having a characteristic transconductance value of T. The at least one resistor provides a resistance substantially equal to 1/T. The transconductive element and the one resistor cooperate to suppress spurious voltage level variations produced by the DC power source. The transconductive element may be realized by a thermionic triode, field effect transistor or other suitable device.

Abstract: A bias offset voltage circuit for controlling one or more devices is disclosed. The bias offset voltage circuit includes a three voltage sources connected in series and a switching element. Each voltage source includes a positive terminal and a negative terminal. The switching element includes a positive input terminal, a negative input terminal, and an output terminal. The negative terminal of the first voltage source is connected to the negative input terminal. The positive terminal of the third voltage source is connected to the positive input terminal. The terminals of the second voltage source are used to drive a first device. The output terminal of the switching element drives a second device. The bias offset voltage circuit may be used to provide proper voltages to each of the devices where the higher-supplied voltage could damage the device supplied with the lower supplied voltage, or vice versa.

Abstract: An actuator driving circuit for driving an electromagnetic actuator, includes a boosting circuit which boosts a source voltage, and a boosted voltage controller which is connected to an output terminal of the boosting circuit, i.e., the downstream of the boosting circuit, to control a boosted voltage generated by the boosting circuit.

Abstract: In a power supply apparatus including a step-up circuit, an output terminal is provided and connectable to an external smoothing circuit formed by a parasitic resistance of a connection layer and an external capacitor. A resistor is connected between an output end of the step-up circuit and the output terminal.

Abstract: A dimmer circuit arrangement is disclosed including a second control circuit (40) for controlling the operation of a triac (50) for delivering current to a load (60), and a first control circuit (10) for controlling the operation of an IGBT power semiconductor switch (20) for controlling the rate of rise of load voltage. The first control circuit also controls the operation of the second control circuit.

Abstract: A power supply device for electric discharge machining includes a switching circuit that supplies a discharge pulse current to an inter-electrode portion that is a portion between an electrode and a workpiece serving as another electrode arranged to be opposed to the electrode at a predetermined interval; and a pulse-width control unit that generates a control pulse signal of a predetermined pulse width in response to a detection signal for starting a discharge at the inter-electrode portion. The switching circuit includes a switching circuit including a switching element suitable for a high-speed operation and a switching circuit including a switching element suitable for a low-speed operation, and receives the control pulse signal in parallel.

Abstract: An improved power supply unit includes a DC power source having a positive terminal and a negative terminal, and a voltage regulating circuit that includes a plurality of elements coupled in series between the positive and negative terminals of the DC power source to regulate the power supply signals supplied thereto to effectively cancel ripple and noise in such power supply signals. In one embodiment, the series-coupled elements include at least one resistor and a transconductive element having a characteristic transconductance value of T. The at least one resistor provides a resistance substantially equal to 1/T. The transconductive element and the one resistor cooperate to suppress spurious voltage level variations produced by the DC power source. The transconductive element may be realized by a thermionic triode, field effect transistor or other suitable device.

Abstract: A torque control device for an electrical tool has a switching circuit, a voltage detecting circuit, a torque detecting circuit and a processor. The switching circuit connects between a motor of the electrical tool and a DC voltage source. The voltage detecting circuit detects voltage or current variation of the motor. The torque detecting circuit based on the detected voltage or current variation data outputs an actual torque value of the motor. The processor compares the actual torque value with a default value to determine whether actual torque is greater than the default. If so, the switching circuit is turned off by the processor to prevent the motor from being damaged.

Abstract: An AC-DC voltage converter includes input terminals with a series circuit connected between the input terminals. The series circuit includes a switching element and a capacitor. The discharge of the capacitor supplies the output voltage of the converter. A control circuit controls the operation of the switching element so that the conducting state of the switching element is controlled exclusively as a function of the input voltage, while the nonconducting state of the switching element is controlled exclusively as a function of the output voltage. The converter has a good dynamic range and allows accurate measurement of current consumption at the output.

Abstract: A method for reducing thermal dissipation in a single PLC package includes implementing a pulse width modulated current regulator including a field effect transistor (FET) switch, and utilizing a turn on delay of the FET to provide a wide operating range of current. The FET has an inherent turn-on time delay that can be exploited such that, as the duty cycle is reduced, the FET's drain to source impedance dominates an inductive path of an output filter and increases output filtering.

Abstract: Field Effect Transistors (FETs) are used to regulate current in a light emitting diode (LED). FETs are fundamentally voltage driven devices, where output current is governed by junction voltage. Since junction voltage can be controlled with little or no support circuitry, FETs present a solution to current regulation where cost, complexity, and perhaps even size are important.

Abstract: A first oscillating signal presenting a peak, a valley, a rising portion gradually increasing from the valley to the peak, and a falling portion gradually decreasing from the peak to the valley is generated. A second oscillating signal presenting an instantly transiting edge, which occurs simultaneously with either the peak or the valley of the first oscillating signal, is generated. The first and the second oscillating signals are input to a first and a second power supply channels, respectively, for converting a DC voltage source into two separate DC output voltages. The first and the second oscillating signals cause at least one switching transition of the first power supply channel to occur separately in the time domain from at least one switching transition of the second power supply channel, thereby preventing transient spikes from superposing together.

Abstract: The invention relates to an LVDS driver for small supply voltages, particularly of less than 2.0 V, for producing a differential output signal (Pout, Nout), having a pull-up transistor (P3, P4) and a pull-down transistor (P1, P2), respectively, for switching the output voltages which are output at the outputs (Pout, Nout). An optimum switching response and hence an undistorted differential signal can be produced by virtue of the pull-up and pull-down transistors (P1-P4) being in the form of PMOS transistors.

Abstract: A voltage generating circuit comprising a capacitor (4), a ferroelectric capacitor (6) serially connected to the capacitor (4), an output terminal (11), a capacitor (10) which grounds the output terminal (11), a supply voltage supplying terminal (13), a switch (1) which connects the supply voltage supplying terminal (13) and the connecting node (N1) of the two capacitors (4, 6), and a switch (9) which connects the connecting node (N1) and output terminal (11); wherein during a first period, with the two switches (1) and (9) placed in the OFF state, a terminal (3) is grounded and a terminal (7) is provided with a supply voltage; wherein during a second period, the terminal (3) is provided with the supply voltage and the switch (9) is placed in the ON state; wherein during a third period, the switch (9) is placed in the OFF state, the switch (1) is placed in the ON state, and the terminal (7) is grounded; wherein during a fourth period, the terminal (7) is provided with the supply voltage; and wherein thereafte

Abstract: To provide a magnetic bearing device capable of lowering the costs required for the manufacture, installation, or the like of a turbo molecular pump by reducing the number of elements of an amplifier circuit that drives, through excitation, electromagnets as well as the number of wires of a cable that connects the each electromagnet and the amplifier circuit to each other, and a turbo molecular pump with the magnetic bearing device mounted thereto. One end of an electromagnet coil is connected to a common node. Also, the other end thereof is connected to an amplifier circuit composed of one transistor and one diode. Further, the one end of the electromagnet coil is common with respect to each of the electromagnets, and the common node R is controlled by an intermediate-voltage maintaining circuit so as to maintain an intermediate voltage.