Texas Instruments Corporation

Microsemi Corporation

Microsemi Corp-analog Mixed Signal Group, Ltd.

David K Lacombe

George C Henry

Chii-Fa Chiou

Yair Darshan

A solid state lighting controller arranged for use with a single stage power factor correction switched mode power supply, a light emitting diode (LED) string and a current sense element arranged to sense current through the LED string, the solid state lighting controller constituted of: a current governor in series with the LED string exhibiting a governor differential amplifier and a governor electronically controlled switch responsive to the output of the governor differential amplifier, the current governor arranged to limit current flow through the LED string responsive to a current limit reference; and a feedback circuit exhibiting an error amplifier, the feedback circuit arranged to feedback a signal to the power factor correction switched mode power supply controller whose value is a function of the difference between the current through the LED string sensed by the current sense element and a target current signal.

LED string driver with power factor corrector and current governor

An apparatus and method for igniting a lamp during a strike mode of an inverter comprising: sequentially controlling a duty cycle sweep and a frequency sweep of driving signals in the inverter to provide an increasing output voltage to the lamp. One embodiment advantageously includes a closed feedback loop to implement the duty cycle sweep and the frequency sweep such that an open lamp voltage is reliably regulated during the strike mode. For example, the closed feedback loop stops the duty cycle sweep or the frequency sweep when the output voltage to the lamp reaches a predetermined threshold and makes adjustments to the duty cycle or frequency the driving signals as needed to keep the output voltage at approximately the predetermined threshold if the lamp has not ignited.

Striking and open lamp regulation for CCFL controller

A feed-forward correction circuit in a PWM controller adjusts an error signal inversely with respect to a supply voltage for a switching voltage regulator to quickly compensate for changes or transients in the supply voltage. The adjusted error signal is provided to a PWM comparator to control a duty cycle of an output signal. The switching voltage regulator can be a DC-to-DC converter or a DC-to-AC converter, and the output signal is used to generate one or more driving signals to control semiconductor switches in the switching voltage regulator. The feed-forward correction circuit uses an offset compensation technique or a translinear circuit to maintain a substantially inverse product relationship between the supply voltage and the duty cycle of the output signal, thereby reducing overshoots and undershoots in a regulated output voltage of the switching voltage regulator.

Method and apparatus to compensate for supply voltage variations in a PWM-based voltage regulator

A write driver controls current path for current of an H-bridge circuit. The H-bridge circuit is controlled by a differential pair switch for adjusting a voltage between the differential pair switch between a first voltage when the H-bridge circuit is switched and a second voltage after the H-bridge circuit is switched.

Accurate adjustable current overshoot circuit

The present invention achieves technical advantages as an overshoot circuit ( ) for a voltage source/impedance based write coil driver circuit ( ) accurately controlling the current (I )through a coil (L ) that is used to write data to a magnetic medium. The circuit ( ) improves the characteristics of the coil.

Overshoot control for voltage source/impedanced based write coil driver

A write driver to supply current to an induction load, including an H-bridge circuit coupled to the induction load to switch the current between a first current path and a second current path, said induction load operative to generate an undershoot current, and an undershoot circuit to control the undershoot current based on a comparison of a reference voltage and a flyback voltage. The undershoot circuit is connected to bases of the transistors of the lower H-bridge circuit.

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Mission Viejo, CA, United States of America

David K Lacombe