Stmicroelectronics S.r.l.

Delta Electronics, Inc.

Sgs-thomson Microelectronics S.r.l.

Claudio Adragna

Giovanni Gritti

Aldo Vittorio Novelli

Mauro Fagnani

Salvatore Tumminaro

Giuseppe Gattavari

Christian Leone Santoro

Albino Pidutti

Alberto Bianco

Alfio Pasqua

Ugo Moriconi

Claudio Spini

Salvatore Giombanco

Paolo Mattavelli

Enrico Orietti

Giorgio Spiazzi

Giovanni Lombardo

Francesco Ferrazza

Michele Grande

Fabrizio Bognanni

Silvio De Simone

Francesco Pulvirenti

Filippo Marino

Milan M Jovanovic

Antonio Giuseppe Grimaldi

Giuseppe Scappatura

Gregorio Bontempo

Laszlo Huber

Alberto Iorio

Maurizio Foresta

Claudia Castelli

Antonio Borrello

Brian T Irving

Massimiliano Gobbi

Marco Sammartano

Mirko Gravati

Santo Ilardo

Vincenzo Bartolo

Eliana Cannella

Stefano Beria

Giuseppe Bosisio

Roberto Quaglino

Ambrogio Giuseppe D'Adda

Silvio Desimone

Monica Micciche'

Alberto Stroppa

A control circuit includes: a flip-flop having an output configured to be coupled to a control terminal of a transistor and for producing a first signal; a comparator having an output coupled to an input of the flip-flop, and first and second inputs for receiving first and second voltages, respectively; a transconductance amplifier having an input for receiving a sense voltage indicative of a current flowing through the transistor, and an output coupled to the first input of the comparator; a zero crossing detection (ZCD) circuit having an input configured to be coupled to a first current path terminal of the transistor and to an inductor, where the ZCD circuit is configured to detect a demagnetization time of the inductor and produce a third signal based on the detected demagnetization time; and a reference generator configured to generate the second voltage based on the first and third signals.

Average current control circuit and method

An LED lighting system includes switching circuitry adjustably driving a string of LEDs and being controlled by a reference current and an enable signal. A controller generates the reference current and enable signal based upon a PWM signal such that the switching circuitry: sources a first LED current to the string of LEDs that is proportional to a duty cycle of the PWM signal when the duty cycle is greater than a threshold duty cycle to thereby perform analog dimming; and sources a second LED current to the string of LEDs that has a duty cycle proportional to the duty cycle of the PWM signal when the duty cycle of the PWM signal is less than the threshold duty cycle, such that an average LED current delivered to the string of LEDs is proportional to the duty cycle of the PWM signal to thereby perform digital dimming.

Dimming interface using combination of analog and digital dimming

An active flyback converter is transitioned between a plurality of operational states based on a comparison of a control voltage signal to voltage thresholds and a count of a number of consecutive switching cycles during which a clamp switch is kept off. The plurality of operational states includes a run state, an idle state, a first burst state, and a second burst state. Each set of consecutive switching cycles of the first burst state includes a determined number of switching cycles during which signals are generated to turn the power switch on and off and to maintain an off state of the clamp switch, and a switching cycle in a determined position in the set of switching cycles during which signals are sequentially generated to turn the power switch on, turn the power switch off, turn the clamp switch on and turn the clamp switch off.

Method for operating in burst mode active clamp flyback converters and corresponding active clamp flyback converter apparatus

In an embodiment, a method for controlling a synchronous rectifier (SR) transistor of a flyback converter includes: determining a first voltage across conduction terminals of the SR transistor; asserting a turn-on signal when a body diode of the SR transistor is conducting current; asserting a turn-off signal when current flowing through the conduction terminals of the SR transistor decreases below a first threshold; generating a gating signal based on an output voltage of the flyback converter and on the first voltage; turning on the SR transistor based on the turn-on signal and on the gating signal; and turning off the SR transistor based on the turn-off signal.

Synchronous rectifier control circuit and method

A control circuit includes an output terminal configured to be coupled to a control terminal of a transistor that has a current path coupled to an inductor; a transconductance amplifier configured to produce a sense current based on a current flowing through the current path of the transistor; and a first capacitor. The control circuit is configured to turn on the transistor based on a clock signal, integrate the sense current with an integrating capacitor to generate a first voltage, generate a second voltage across the first capacitor based on a first current, generate a second current based on the second voltage, generate a third voltage based on the second current, turn off the transistor when the first voltage becomes higher than the third voltage; discharge the integrating capacitor when the transistor turns off; and regulate an average output current flowing through the inductor based on the first current.

In an embodiment, a method for operating an ACF converter includes: turning on a low-side transistor that is coupled between a primary winding of a transformer and a reference terminal to cause a forward current to enter the primary winding, turning off the low-side transistor; after turning off the low-side transistor, turning on a high-side transistor that is coupled between the primary winding and a clamp capacitor to cause a reverse current to flow through the primary winding; and after turning on the high-side transistor, when an overcurrent of the reverse current is not detected, keeping the high-side transistor on for a first period of time, and turning off the high-side transistor after the first period of time, and when the overcurrent of the reverse current is detected, turning off the high-side transistor without keeping the high-side transistor on for the first period of time.

Cycle-by-cycle reverse current limiting in ACF converters

In an embodiment, a control circuit includes: an output terminal configured to be coupled to a control terminal of a transistor that is coupled to an inductor; a logic circuit configured to control the transistor using a first signal; a zero crossing detection circuit configured to generate a freewheeling signal indicative of a demagnetization of the inductor; a comparator having first and second inputs configured to receive a sense voltage indicative of a current flowing through the transistor and a reference voltage, respectively, and an output configured to cause the logic circuit to deassert the first signal; and a reference generator configured to generate the reference voltage and including: a current generator, a capacitor and a resistor coupled to the output of the reference generator, and a switch coupled in series with the resistor and configured to be controlled based on the first signal and the freewheeling signal.

QR-operated switching converter current driver

A control circuit includes: an output terminal configured to be coupled to a control terminal of a transistor that has a current path coupled to an inductor; a transconductance amplifier configured to produce a sense current based on a current flowing through the current path of the transistor; and a first capacitor, where the control circuit is configured to: turn on the transistor based on a clock signal, integrate the sense current with an integrating capacitor to generate a first voltage, generate a second voltage across the first capacitor based on a first current, generate a second current based on the second voltage, generate a third voltage based on the second current, turn off the transistor when the first voltage becomes higher than the third voltage; discharge the integrating capacitor when the transistor turns off; and regulate an average output current flowing through the inductor based on the first current.

A driver circuit for a resonant converter includes a comparator that generates a first control signal indicating when a resonant current changes sign. A first ramp generator circuit outputs a first ramp signal, and a comparison circuit determines whether the first ramp signal reaches a reference threshold. The driver circuit drives a half-bridge via drive signals during consecutive first second switching semi-periods, each of which ends when the comparison circuit indicates the first ramp signal has reached a reference threshold. A control circuit generates in each of the first and the second switching semi-periods control signals indicating a first interval and a second interval. A correction circuit modifies the first ramp signal to have a first gradient value during the first interval and a second gradient value during the second interval. Alternatively, the correction circuit modifies a reference threshold by adding a second ramp signal to an initial threshold value.

Driver circuit for a resonant converter, related integrated circuit, electronic converter and method

A PWM controlled multi-phase resonant voltage converter may include a plurality of primary windings powered through respective half-bridges, and as many secondary windings connected to an output terminal of the converter and magnetically coupled to the respective primary windings. The primary or secondary windings may be connected such that a real or virtual neutral point is floating.

Multi-phase resonant converter and method of controlling it

An embodiment PFC control circuit includes a first terminal providing a drive signal to an electronic switch of a boost converter, a second terminal receiving a feedback signal indicative of an output voltage generated by the boost converter, and a third terminal connected to a compensation network. An error amplifier generates a current as a function of the voltage at the second terminal and a reference voltage, wherein an output of the error amplifier is coupled to the third terminal. A driver circuit generates the drive signal as a function of the voltage at the third terminal, and selectively activates or deactivates the generation of the drive signal as a function of a burst mode enable signal. A detection circuit generates the burst mode enable signal as a function of the voltage at the second terminal.

PFC control circuit for a boost converter, related integrated circuit, boost converter, power supply and method

The present disclosure is directed to a primary-controlled high power factor quasi resonant converter. The converter converts an AC power line input to a DC output to power a load, generally a string of LEDs, and may be compatible with phase-cut dimmers. The power input is fed into a transformer being controlled by a power switch. The power switch is driven by a controller having a shaping circuit. The shaping circuit uses a current generator, switched resistor and capacitor to produce a reference voltage signal. The controller drives the power switch based on the voltage reference signal, resulting in a sinusoidal input current in a primary winding of the transformer, resulting in high power factor and low total harmonic distortion for the converter.

Control method and device employing primary side regulation in a quasi-resonant AC/DC flyback converter

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Monza, Italy

Claudio Adragna