Showing papers on "Voltage regulator published in 1998"

A low-voltage, low quiescent current, low drop-out regulator

Abstract: The demand for low-voltage, low drop-out (LDO) regulators is increasing because of the growing demand for portable electronics, i.e., cellular phones, pagers, laptops, etc. LDO's are used coherently with dc-dc converters as well as standalone parts. In power supply systems, they are typically cascaded onto switching regulators to suppress noise and provide a low noise output. The need for low voltage is innate to portable low power devices and corroborated by lower breakdown voltages resulting from reductions in feature size. Low quiescent current in a battery-operated system is an intrinsic performance parameter because it partially determines battery life. This paper discusses some techniques that enable the practical realizations of low quiescent current LDO's at low voltages and in existing technologies. The proposed circuit exploits the frequency response dependence on load-current to minimize quiescent current flow. Moreover, the output current capabilities of MOS power transistors are enhanced and drop-out voltages are decreased for a given device size. Other applications, like dc-dc converters, can also reap the benefits of these enhanced MOS devices. An LDO prototype incorporating the aforementioned techniques was fabricated. The circuit was operable down to input voltages of 1 V with a zero-load quiescent current flow of 23 /spl mu/A. Moreover, the regulator provided 18 and 50 mA of output current at input voltages of 1 and 1.2 V, respectively.

Statcom controls for operation with unbalanced voltages

Abstract: Voltage sourced static VAr compensators such as the Statcom need to be able to handle unbalanced voltages. Mild imbalance can be caused by unbalanced loads while severe short-term imbalance can be caused by power system faults. A synchronous frame voltage regulator is presented that works even when three phase symmetry is lost. This regulator addresses voltage imbalance by using separate regulation loops for the positive and negative sequence components of the voltage. The proposed regulator allows the Statcom to ride through severe transient imbalance without disconnecting from the power system and, further, to assist in rebalancing voltages. The regulator maintains sufficient bandwidth to perform flicker compensation. The controller's performance is simulated for a Statcom in a model distribution system where it is subjected to a severe single line to ground fault and a rapidly varying three phase load.

A 0.5-mW passive telemetry IC for biomedical applications

Abstract: A low-power, single-chip, one-channel, fully implantable microtransponder system for low-frequency biomedical sensor applications is described. The circuit is powered by an external RF source at 27/40 MHz. No battery is required. Wireless communication with external monitoring units is realized by absorption modulation. As the radiated power received by a small coil can be as low as a few milliwatts, the data acquisition/transmission system has been optimized for low power consumption. The system has been integrated in a 2-/spl mu/m 40-V BiCMOS technology. It includes a low-offset amplifier, a low-pass notch filter, an A/D converter, a voltage doubler/rectifier, as well as a low-power voltage regulator. The implemented switched-capacitor amplifier features 45-/spl mu/V offset and an integrated noise of 21 /spl mu/V for a bandwidth of 30 Hz while consuming less than 30 /spl mu/W power. The digitized sensor data are transmitted as low duty-cycle PPM-AM signals with a rate of 1 kBd. The entire system, including the 1.6-k/spl Omega/ bridge sensor, consumes only 520 /spl mu/W, which makes it well suited for long-term monitoring of biomedical signals.

Optimized frequency-shaping circuit topologies for LDOs

Abstract: Typical low drop-out (LDO) regulator architectures suffer from an inherent load regulation performance limitation. This limitation manifests itself through limited DC open-loop gain, and results from stringent closed-loop bandwidth requirements. The frequency response of the system is highly sensitive to the loading conditions, thereby making proper compensation a laborious endeavor. This paper discusses and addresses the limitation on regulating performance imposed by frequency compensation. Several LDO circuit topologies are subsequently developed to this end. They enhance load regulation performance by relaxing the DC open-loop gain restrictions. The circuit structures essentially alter the frequency response of the system via the error amplifier. A low drop-out regulator adopting an embodiment of the proposed technique was fabricated in the MOSIS 2-/spl mu/m process technology. The system, designed for an output capacitor of 4.7 /spl mu/F, was stable with an equivalent series resistance (ESR) ranging from 0 to 12 /spl Omega/, bypass capacitors ranging from 0 to 2.2 /spl mu/F, and a load current ranging from 0 to 50 mA.

Single-stage single-switch power-factor-correction AC/DC converters with DC-bus voltage feedback for universal line applications

Abstract: Single-stage single-switch power-factor-correction (S/sup 4/-PFC) AC/DC converters with DC-bus voltage feedback are proposed. The DC-bus voltage stress at light load for the S/sup 4/-PFC converter is first analyzed. The DC-bus voltage negative feedback concept in the power stage to suppress the DC-bus voltage stress is then proposed. Design considerations of total harmonic distortion (THD), power factor (PF), DC-bus voltage stress, and the boost inductor are discussed. A S/sup 4/-PFC converter is analyzed and implemented with 5 V 12 A output as an example. It is shown that the DC-bus voltage is limited within 405 V from no load to full load, and the measured line input-current harmonics satisfy the IEC 1000-3-2 Class D requirements with universal line input. The measured efficiency and PF are about 71% and 0.93, respectively. The experimental results show that using the DC-bus voltage feedback to reduce the DC-bus voltage is effective.

DC voltage control and stability analysis of PWM-voltage-type reversible rectifiers

Abstract: A PWM voltage rectifier has useful characteristics on its DC and AC sides. On its DC side, a DC-link unidirectional voltage is obtained and bidirectional power transfer capability is possible by reversing the flow direction of the DC-link current. On its AC side, near sinusoidal current waveforms and AC four-quadrant operation can be obtained, leading to high-quality power being exchanged between the power converter and the mains. The use of AC filters becomes unnecessary. The rectifier DC voltage must be regulated to a constant value. In this paper, three solutions for the DC voltage control are presented. In the first solution, the DC voltage is controlled by acting upon the quadrature component of the power converter fundamental Park's voltages with relation to the mains voltages. Slow responses are necessary because of stability reasons. Also, load power variations produce both active and reactive power variations in the power converter AC side. To improve the DC voltage response, a second control solution is presented. The power converter currents in Park's coordinates must be controlled. The DC voltage is controlled by controlling the direct Park's current component and, thus, acting only on the active power of the converter AC side. Faster responses are achieved. In this case, load power variations do not produce reactive power variations in the converter AC side. The third control solution is a simplified version of this last one. Experimental results from a 2 kVA IGBT-based prototype showing good system dynamic performance are presented.

Embedded 5 V-to-3.3 V voltage regulator for supplying digital IC's in 3.3 V CMOS technology

Abstract: A fully integrated 5 V-to-3.3 V supply voltage regulator for application in digital IC's has been designed in a 3.3 V 0.5 /spl mu/m CMOS process. The regulator is able to deliver peak current transients of 300 mA, while the output voltage remains within a margin of 10% around the nominal value. The circuit draw's a static quiescent current of 750 /spl mu/A during normal operation, and includes a power-down mode with only 10 /spl mu/A current consumption. The die area is 1 mm/sup 2/, and can be scaled proportional to the maximum peak current. Special precautions have been taken to allow 5 V in the 3.3 V process.

Microprocessor controlled electronic ballast

Abstract: An electronic ballast includes an AC to DC converter (51, 52) for power factor correction, a bulk capacitor (53, 120) for storing energy from the converter, and a microprocessor controlled, half-bridge inverter (54) including a series resonant, direct coupled output (35, 36). Input ports of the microprocessor (65) are coupled to several locations within the ballast to monitor the operation of the ballast or the operation of a gas discharge lamp coupled to the ballast. An analog voltage limiter (Q5) overrides the microprocessor to limit output voltage under fault conditions. A storage capacitor (121), connected in series with the bulk capacitor (120), stores energy at low voltage for powering the microprocessor. The microprocessor is programmed to provide lamp protection features, lumen maintenance, and a warm-up period for a lamp. The microprocessor is also programmed to meet the operating requirements of world markets and of different lamp types.

Disk drive utilizing Bemf of spindle motor to increase VCM voltage during seeks

Abstract: A disk drive is connectable to a power supply having a fixed DC voltage The disk drive includes a voice coil motor (VCM) and a spindle motor having a plurality of windings and a rotor rotatable at a variable spin-rate A spindle motor driver is coupled to the fixed DC voltage and at least one of the windings for controlling the spin-rate of the rotor The rotor has permanent magnets that induce an AC voltage across the windings while the rotor is rotating A rectifier circuit rectifies the AC voltage across at least one of the windings to produce a rectified DC voltage A first switch provides the rectified DC voltage to a first node A second switch provides the fixed DC voltage to the first node The first node has a first node DC voltage that is determined by the rectified DC voltage provided by the first switch and the fixed DC voltage provided by the second switch The first node DC voltage is greater than the fixed DC voltage during a track seeking operation in the disk drive A VCM driver includes switching elements that selectively provide the first node DC voltage to the VCM The increased VCM voltage allows faster access times and more efficient VCM operation

Analysis of a novel solid state voltage regulator for a self-excited induction generator

Abstract: An analysis of a solid state voltage regulator for a self-excited induction generator (SEIG) using a static condenser (STATCON) is presented. The power circuit of the STATCON-based voltage regulator employs a three-phase current controlled voltage source inverter (CC-VSI) with an electrolytic capacitor in its DC bus. The control scheme consists of two PI voltage controllers and one hysteresis current controller. The mathematical model of the proposed scheme is developed to simulate the improved performance of the SEIG with a STATCON-based voltage regulator. The voltage regulator provides the SEIG with the desirable feature of a synchronous condenser, and is capable of operating in capacitive and inductive modes. The use of STATCON saves the SEIG from de-excitation during the severe condition of load perturbation. It has a fast dynamic response for regulating the voltage when the SEIG faces sudden application/removal of load. The voltage regulating scheme is adaptive to the changing load condition and hence it is possible to operate the SEIG at almost constant voltage from no load to full load.

A statistical analysis of the effect of electric vehicle battery charging on distribution system harmonic voltages

Abstract: This paper presents a statistical method for predicting the effect that widespread electric vehicle (EV) battery charging will have on power distribution system harmonic voltage levels. The method uses a statistical model for nonlinear load currents to generate the probabilities of specific harmonic voltage levels. The statistical model for the harmonic currents produced by a concentration of EVs accounts for partial harmonics cancellation introduced by uncertainty and variation in charger start-time and initial battery state-of-charge. A general solution technique is presented along with several examples using data from a commercially-available EV charger and an actual power distribution system. The results show that there is a definite threshold penetration below which EV charging has negligible impact on the number of buses whose voltage total harmonic distortion (THD/sub V/) exceeds 5%. During the late evening of a summer day, the authors' example distribution system can accommodate EV penetration levels as high as 20%. A similar analysis of the system in the spring or fail indicates that the system can accommodate a 15% EV penetration before THD/sub V/ exceeds 5% at an unacceptable number of buses.

Polyphase synchronous switching voltage regulators

Abstract: The invention provides polyphase synchronous switching regulator circuits that include N power stages connected in parallel, with each stage synchronized to a timing control signal that is 360°/N out of phase from one another. Each power stage supplies current I OUT /N to the load. Current-mode and voltage-mode control implementations are described that provide efficient, low voltage, high current synchronous switching regulator circuits that have low input ripple current, low EMI, high slew-rate capability and low output ripple.

Discrete-time sampling of data for use in switching regulators

Abstract: A voltage regulator with a switch to alternately couple and decouple an input terminal to an output terminal with a variable duty cycle and a filter disposed between the input terminal and the output terminal to provide a substantially DC voltage at the output terminal A sampling circuit makes measurements of an electrical characteristic of the voltage regulator at discrete moments of time, such as just before the opening and closing of the switch A feedback circuit is coupled to the sampling circuit and the switch, and is configured to use the measurements to control the duty cycle to maintain the DC voltage substantially constant The feedback circuit uses the switch as the resistive element in order to measure the current passing through the voltage regulator

Step-up/down AC voltage regulator using transformer with tap changer and PWM AC chopper

Abstract: A step-up/down AC voltage regulator is proposed, in which a tap-changing transformer and a pulsewidth modulation (PWM) AC chopper are combined. The proposed regulator can step up or down the output voltage to input voltage. Also, the proposed regulator restrains more harmonics of output voltage compared to the conventional PWM regulator. The input current flows continuously in the proposed regulator, while it flows discontinuously in the conventional PWM regulator. Through digital simulation, several characteristics are investigated theoretically and then compared with those of conventional schemes. Practical verification of the theoretical predictions is presented to confirm the capabilities of the proposed regulator.

Luo-converters, voltage lift technique

Abstract: The voltage lift technique is a popular method widely applied in electronic circuit design. Since the effect of parasitic elements limits the output voltage and power transfer efficiency of DC-DC converters, the voltage lift technique opens a good way to improve circuit characteristics. After long term research, this technique has been successfully applied for DC-DC converters. Luo-converters are a series of new DC-DC step-up (boost) converters, which were developed from prototypes using voltage lift technique. These converters perform positive to positive DC-DC voltage increasing conversion with high power density, high efficiency and cheap topology in simple structure. They possess high output voltage with small ripples. Therefore, these converters will be widely used in computer peripheral equipment and industrial applications, especially for high output voltage projects.

CMOS bandgap voltage reference

Abstract: A bandgap voltage reference circuit for 0.35-μm, 3-volt CMOS technology operates in an essentially temperature independent manner and having low supply voltages. The bandgap voltage reference circuit incorporates two operational amplifiers. One operational amplifier biases bipolar devices of the circuit and generates a PTAT voltage across a resistor, and the other operational amplifier buffers a voltage related to the PTAT voltage and a voltage across one bipolar device to generate the bandgap voltage reference. In one embodiment, the circuit includes a start-up circuit to ensure a stable and desired start-up state. A current bias may also be provided. The bandgap voltage reference of the second operational amplifier may also provide a regulated supply for the first stage of the circuit. The second operational amplifier also provides a buffered output to a resistor divider circuit to supply a voltage divider to generate voltages below the 1.24-volt bandgap voltage. The bandgap voltage reference circuit includes two versions, one which is optimized for a low supply voltage potential VDD of approximately 1.8 volts and the other for a standard supply voltage VDD of approximately 2.4 volts.

Semiconductor circuit for an electronic unit

Abstract: A semiconductor circuit for an electronic unit having at least one microcontroller comprises at least one voltage regulator for providing, from a first supply voltage, at least one second supply voltage for the microcontroller and for circuits of the unit which cooperate with the microcontroller. The circuit further comprises, in monolithic form, a transceiver unit having transmitting and receiving device for coupling a microcontroller to the two-wire bus. This monolithic construction may additionally comprise watchdog functions, various wake-up functions and an interface via which a serial data exchange with the at least one microcontroller is possible. Furthermore, it may have an apparatus for determining, throughout the network, bus subscribers having reference-ground potential faults and for quantifying such faults.

VRM transient study and output filter design for future processors

Abstract: In this paper, the transient response of the (voltage regulator module) VRM output voltage when the processor has a fast load change is analyzed. The parasitic parameters play important roles in the transient. The system can be divided into several resonant loops. Each loop can be approximately considered as a decoupled second order system. The transient response is affected by the magnitude of the load change rather than the slew rate of it. Limitations of the present VRM topology for future specifications and output filter design are discussed.

Inter-area oscillation damping with power system stabilizers and synchronized phasor measurements

Abstract: Low-frequency oscillations are detrimental to the goals of maximum power transfer and optimal power system security. A contemporary solution to this problem is the addition of power system stabilizers to the automatic voltage regulators on the generators in the power system. The damping provided by this additional stabilizer provides the means to reduce the inhibiting effects of the oscillations. A novel modification of this controller is the inclusion in the feedback loop of information from a remote source. In this manner, the controller acts on the changes from the local source and the remote source. As is demonstrated, this yields a controller capable of more rapidly diminishing the oscillations in a test power system.

Voltage down converter for multiple voltage levels

Abstract: A voltage regulator circuit in an integrated circuit (IC) device such as a Complex Programmable Logic Device (CPLD) comprises a reference voltage generator, a tuning circuit, and an output driver circuit. The reference voltage generator converts an external supply voltage provided to the IC device into a stable reference voltage. The tuning circuit converts the stable reference voltage into a desired internal supply voltage, such as the reduced voltage required by deep sub-micron transistors. The output driver circuit provides the desired internal supply voltage with sufficient current to properly power the circuits of the IC device. The tuning circuit includes an op-amp and resistive elements configured in a voltage divider configuration in the negative feedback loop of the op-amp. The output of the op-amp can be set to the desired internal supply voltage by properly sizing the resistive elements. By making at least one of the resistive elements adjustable, a variable internal supply voltage can be provided by the voltage regulator circuit.

Enhanced low-dose-rate sensitivity of a low-dropout voltage regulator

Abstract: Ionization-induced degradation of the 29372 low-dropout voltage regulator is most severe at low-dose-rate (/spl sim/10 mrad(SiO/sub 2/)/s) and zero load current. The most sensitive parameter is the maximum output drive current, which is a function of the gain of the large lateral pnp output transistor. Significant degradation of this parameter occurs at 5-10 krad(SiO/sub 2/) at low-dose-rate. A moderate load current (/spl sim/250 mA) during irradiation significantly mitigates the damage. The mitigation of the damage is proportional to irradiation load current and is not a strong function of irradiation temperature or input voltage. The mechanism for the mitigation of damage appears to be current density dependent passivation of interface and/or border traps by mobile hydrogen-related species. The worst-case space system application is in unbiased spares.

Drive control equipment of ac motor

Abstract: PROBLEM TO BE SOLVED: To reduce torque shocks generated in an AC motor at the switching of a square wave voltage phase control mode and a PWM current control mode. SOLUTION: This drive control equipment is so constituted that a switching command can be supplied selectively to an inverter 36 from a PWM circuit 30 and a square wave generating part 32. At the switching of both control modes, a quasi-sine wave voltage which has a voltage amplitude |V| formed by a voltage amplitude controller 16 and a voltage phase ψ formed by a voltage phase controller 18 is applied to a motor 38, and control is so performed that the torque of the motor 38 remains constant.

Investigation of candidate VRM topologies for future microprocessors [voltage regulator modules]

Abstract: Future generation microprocessors are expected to exhibit much heavier loads and much faster transient slew rates. Today's voltage regulator module (VRM) will need a large amount of extra decoupling and output filter capacitors to meet future requirements, which basically makes the existing VRM topologies impractical. In this paper, a candidate topology, interleaved quasi-square wave, is proposed. Its design, simulation and experimental results are presented.

Variable-voltage CPU voltage regulator

Abstract: An integrated CPU has an on-board switching voltage regulator with an electrically-erasable programmable read-only memory electronically accessible for storing a feedback reference coefficient for control. In further embodiments, output voltage is tuned via a second EEPROM storing an electronically accessible value in concert with a solid-state resistor ladder. In other embodiments, signals on interrupt lines to the CPU are monitored to provide a prewarning of impending activity by the CPU requiring dramatically increased current flow. In yet other embodiments, solid state circuitry is provided to reduce or eliminate capacitors used for dealing with input current surges to the CPU.

Voltage regulator with output pull-down circuit

Abstract: A voltage regulator circuit includes: an output transistor MP X coupled between a voltage supply node V CC and an output node V OUT ; an amplifier A 1 coupled to the output transistor MP X for controlling the response of the output transistor MP X ; feedback circuitry R 1 and R 2 connected between the output node V OUT and the amplifier A 1 , the feedback circuitry R 1 and R 2 providing feedback to the amplifier A 1 ; and a pull-down circuit PD 1 coupled to the output node V OUT .

Voltage booster for enabling the power factor controller of a LED lamp upon low ac or dc supply

Abstract: The light-emitting-diode lamp comprises a set of light-emitting diodes, a rectifier and power converter circuit, and a power factor controller. The rectifier and power converter circuit converts ac or dc voltage and current from a power source to dc voltage and current supplied to the set of light emitting diodes. The rectifier and power converter circuit includes an electronic switch through which it is supplied with ac or dc voltage and current from the power source, and an inductor device including windings adapted to charge a capacitor with a voltage signal representative of the amplitude of the ac or dc voltage from the power source. The power factor controller is responsive to the voltage signal across the capacitor for controlling the electronic switch of the rectifier and power converter circuit in view of supplying dc voltage and current to the set of light emitting diodes while maintaining the power factor of the light-emitting-diode lamp equal to or close to unity. The power factor controller comprises a voltage comparator supplied with the voltage signal across the capacitor for enabling operation of the power factor controller as long as the ac or dc voltage from the power source has an amplitude higher than a first predetermined voltage threshold. A voltage boosting circuit raises the amplitude of the voltage signal across the capacitor when the ac or dc voltage from the power source is lower than the first voltage threshold to keep operation of the power factor controller enabled as long as the ac or dc voltage is higher than a second predetermined voltage threshold lower than the first predetermined voltage threshold.

Optoelectronic transmitter having an improved power control circuit for rapidly enabling a semiconductor laser

Abstract: An optoelectronic transmitter is provided including a laser diode. A control circuit for driving the laser diode includes a current source which provides a DC bias current to the laser diode, and the laser diode emits an optical signal having an average power determined by the magnitude of the bias current. A voltage regulator establishes a regulated supply voltage which is input to a first reference circuit and a feedback monitor circuit. The first reference circuit establishes a first fixed reference voltage. The feedback monitor circuit includes a monitor device for measuring the optical power emitted by the laser diode, and the monitor circuit establishes a variable monitor voltage proportional to the optical power measured by the monitor device. An op-amp compares the first fixed reference voltage and the feedback monitor voltage, and the output voltage of the op-amp controls the magnitude of the bias current output by the current source. A disable switch is incorporated for selectively blocking the bias current to the laser upon receipt of a DISABLE signal. A second reference circuit is provided for developing a second derived reference voltage, and an analog switch which is also actuated by the DISABLE signal connects the second derived reference voltage to the feedback monitor circuit while the DISABLE signal is active. Otherwise, the analog switch connects the regulated supply voltage to the feedback monitor circuit at all other times.

Step-up/step-down voltage regulator using an MOS synchronous rectifier

Abstract: A circuit and method for providing a voltage regulation despite variations in the supply voltage and/or the load utilize a MOS synchronous rectifier in a flyback topology to perform both step-up and step-down operations. The circuit operates in a boost-type operation until the voltage at an output terminal exceeds a predetermined shut-off voltage. At such time, a duty cycle of the circuit is suspended until the voltage at the output terminal falls below the predetermined shut-off voltage. Triggering the duty cycle and the suspension of the duty cycle are dependent solely upon the voltage at the output terminal. The circuit includes a steering device that connects the body of MOS synchronous rectifier to either its source or its drain to consistently configure the MOS synchronous rectifier in a reverse-biased condition. Preferably, the steering device is comprised of two PMOS transistors that are controlled by the voltages at the source and drain of MOS synchronous rectifier.

Switching regulator capable of increasing regulator efficiency under light load

Abstract: A switching regulator of which efficiency is increased while the switching regulator is operated under low load condition is disclosed. The switching regulator is arranged by: a reference voltage circuit for producing a reference voltage; an error amplifier for entering thereinto the reference voltage and a measuring voltage produced by subdividing an output voltage from the switching regulator and for amplifying a difference voltage between the reference voltage and the measuring voltage; an oscillator circuit for outputting an oscillator signal; a PWM comparator for comparing an output voltage of the error amplifier with an output voltage of the oscillator circuit; load detecting means for detecting an output load current; and efficiency varying means for varying an efficiency of the switching regulator in response to load conditions detected by the load detecting means.

Internal cmos reference generator and voltage regulator

Abstract: An embodiment of the present invention includes a reference generator and voltage regulator circuit (110) for deriving a reference signal having a reference voltage from a system voltage source having a system voltage level wherein the reference voltage level remains substantially unaffected by variations in the system voltage level and variations in temperature, the circuit (110) including a voltage reference sub-circuit (112), a voltage regulator sub-circuit (114), a voltage translator sub-circuit (116), a filter sub-circuit (118) and an output sub-circuit (120).