Texas Instruments Corporation

Linear Technology Corporation

James Edward Wells

Vishal I Gupta

John Christopher Canfield

Mark G Jordan

James R Garrett

Norbert James Hepfinger

John Cristopher Canfield

A buck-boost converter with a switch controller may cause switches A, B, C, and/or D to cyclically close such that switches B and C are closed during at least one interval of each cycle during both the buck and boost modes of operation. The switch controller may in addition or instead cause switches A, B, C, and/or D to cyclically close based on a control signal such that switches A and D are closed during an interval of each cycle and such that these intervals are never both simultaneously modulated by a small change in the control signal during any mode of operation.

Continuously switching buck-boost control

Voltage regulators and methods for regulating voltages are disclosed. A switching circuit with an inductor and a plurality of switches may be used to produce a regulated voltage from an unregulated voltage source. A control circuit may be used to monitor the voltages at the input and output of the voltage regulator, and operate the switches in either a buck, boost, or buck-boost mode depending on the relationship between the voltages at the input and output of the voltage regulator.

Adaptive control for inducer based buck-boost voltage regulators

A control circuit for a piezo transformer based power supply includes oscillator circuitry, drive circuitry, sense circuitry, and feedback circuitry collectively operating to regulate an operational parameter of the supply, such as the current supplied to a cold cathode fluorescent lamp (CCFL). The feedback circuitry includes initialization circuitry that establishes an initial value of an oscillator control signal corresponding to an initial operating frequency, and thereafter permits the feedback circuitry to gradually drive the oscillator control signal to a normal operating value such that the operating frequency is swept from the initial operating frequency to a normal operating frequency. When controlling the power supplied to a CCFL, the initial operating frequency is preferably a maximum frequency of the oscillator, and the operating frequency is swept downward so as to pass through the frequency at which the lamp &ldquo;strikes&rdquo;, or begins conduction, and thereafter into regulation.

Control circuit employing preconditioned feedback amplifier for initializing VCO operating frequency

A multi-channel interleaved power converter includes first and second per-channel conversion circuits, each including a pulse width modulator (PWM), a driver PWM, an output inductor carrying load current, and a current controlled current source (CCCS) coupled to sense the inductor current. The inductors of the different channels are coupled in common to an output node of the power converter. Summing circuitry is operative (i) to subtract the output current of the second channel CCCS from the output current of the first channel CCCS, (ii) to convert the difference current into an offset, and (iii) to apply the offset to a first PWM control signal to generate a second PWM control signal for the second channel. The PWM control signals cause respective currents to be established in the inductors of the different channels according to a predetermined desired current relationship, such as equality.

Multi-channel interleaved power converter with current sharing

A control circuit for a piezo transformer based power supply for a fluorescent lamp includes driver circuitry generating pulse waveforms for providing excitation to primary inputs of the piezo transformer, and circuitry for regulating lamp current and the voltage across the piezo transformer primary inputs. The frequency of the pulse waveforms is varied in response to the magnitude of lamp current to maintain a predetermined desired lamp current as represented by a current reference signal. The duty cycle of the driver circuitry is varied in response to the magnitude of the voltage across the piezo transformer primary inputs to maintain a predetermined desired piezo primary voltage as represented by a voltage reference signal. The piezo transformer is operated as close to resonance as possible, contributing to greater circuit efficiency. The driver circuitry in the control circuit employs four transistors arranged as a full bridge with respect to the piezo transformer primary inputs. The phase of drive signals supplied to one pair of the transistors is varied with respect to the phase of drive signals supplied to the other pair, thereby varying duty cycle and average voltage of the piezo transformer primary inputs. A controller integrated circuit contains a number of components of the control circuit, enabling its use in a variety of piezo-based power supply applications.

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Merrimack, NH, United States of America

James Edward Wells