Stmicroelectronics S.r.l.

Stmicroelectronics Gmbh

Sgs-thomson Microelectronics S.r.l.

Albino Pidutti

Claudio Adragna

Claudio Diazzi

Mauro Fagnani

Axel Alegre De La Soujeole

Stefano Beria

Fabrizio Martignoni

Mario Giovanni Scurati

Elango Pakriswamy

Fabio Vio

Marco Alessandro Legnani

Pierandrea Borgato

Roberto Quaglino

Francesco Pulvirenti

Aldo Vittorio Novelli

Angelo Genova

Gregorio Bontempo

Giuseppe Gattavari

Ignazio Salvatore Bellomo

Paolo Sandri

Ugo Moriconi

Alessandro Camera

Flavia Borella

Francesca Sandrini

Controlling a resonant switching system, which includes a first switch and a second switch in a half-bridge configuration for driving a resonant load. A corresponding control system includes command means for switching on and switching off the switches alternatively according to a working frequency of the switching system. The control system includes detection means for detecting a zeroing of a working current being supplied by the switching system to the resonant load in a temporal observation window; the observation window follows each switching off of at least one of the switches, and has a length equal to a fraction of a to working period of the switching system. Correction means are then provided for modifying the working frequency in response to each detection of the zeroing in the observation window.

Control of a resonant switching system with monitoring of the working current in an observation window

A bootstrap circuit for switching power supplies (SMPS), a switching power supply including a bootstrap circuit, and an integrated circuit of a switching power supply, are provided. The bootstrap circuit () for switching power supplies includes a first supply voltage (Vin) coming from a first terminal and a second supply voltage (Vcc) coming from a second terminal and a third terminal (). The bootstrap circuit includes: a first current path between the first terminal and the third terminal (); a second current path between the first terminal and the second terminal; a third current path between the second terminal and the third terminal (); and a two-way voltage regulator (M, Dz, R, R) placed along the second current path.

Starting circuit for switching power supplies

An H-bridge circuit having a boost capacitor coupled to the gate of the low-side driver. A driver, in the form of a switching transistor is connected between the load and ground, thus providing a low-side driver. A capacitor is coupled to the gate of the low-side driver to provide a boosted voltage for rapid turn on of the gate. The size of the capacitor selected to be similar to the size of the capacitance associated with the low-side driver transistor.

Boost capacitor layout technique for an H-bridge integrated circuit motor controller to ensure matching characteristics with that of the low-side switching devices of the bridge

The present invention refers to a switching power supply, in particular to a power factor corrector, and more particularly to a circuit for the programmable protection against output over-voltages. It also refers to a power factor corrector integrated circuit comprising a circuit for the programmable protection against output over-voltages. In one embodiment the circuit for the programmable protection against output over-voltages in a power Factor corrector comprises means for detecting a signal proportional to the output voltage; a first preset reference voltage; a second preset reference voltage; a transconductance amplifier which receives in input the signal proportional to the output voltage and the first preset reference voltage; a comparator which receives in input the signal proportional to the output voltage and the second preset reference voltage; means suitable for absorbing a current coming from the signal proportional to the output voltage.

Circuit for the programmable protection of output over-voltages in a power factor corrector

A power factor correction device for switching power supplies is described, which comprises a converter () and a control device () coupled with said converter () in such a way as to obtain from a input network alternated voltage (Vin) a direct regulated voltage (Vout) at the output terminal. The converter () comprises a power transistor (M) and the control device () comprises an error amplifier () having in input at the inverting terminal a first signal (Vr) proportional to said regulated voltage (Vout) and at the non-inverting terminal a voltage reference (Vref), at least one capacitor (C) having a first terminal and a second terminal which are coupled respectively with the inverting terminal and the output terminal () of the error amplifier () and a driving circuit () of said power transistor (M) which is coupled with the second terminal of said capacitor (C). The control device () comprises interruption means (SW) placed between the output terminal () of said error amplifier () and the second terminal of said capacitor (C) and control means () able to activate said interruption means (SW) so as to control the interruption of the connection between the error amplifier () and said driving circuit () for at least one time period (T) lower than the time period (Tciclo) in which said control device () is operative.

Power factor correction device for switching power supplies

A programmable oscillator comprises a capacitor; a current generator couplable to said capacitor that generates a charging current of said capacitor; further comprising at least one resistance coupled to said capacitor; a comparator coupled to said capacitor for comparing a voltage at the terminals of said capacitor with a prefixed reference voltage and for generating an output signal; a first switch, controlled by said output signal, coupled to said capacitor that creates a current path able to facilitate the discharging of said capacitor.

Programmable oscillator

A device is described for the correction of the power factor in power supply units with forced switching operating in transition mode. Said device comprises a converter and a control device coupled with said converter so as to obtain a regulated voltage on the output terminal from an alternating network input voltage. The converter comprises a power transistor whilst the control device comprises a pilot circuit suitable for determining the switch-on time and the switch-off time of the power transistor. The control device furthermore comprises control means coupled with said pilot circuit and with said converter and capable of prolonging the switch-on time of the power transistor at the instants of time wherein the alternating network voltage substantially takes on the value zero.

Device for the correction of the power factor in power supply units with forced switching operating in transition mode

A device for the correction of the power factor in power supply units with forced switching operating in transition mode is described. The device comprises a converter and a control device coupled to said converter so as to obtain from an alternating network input voltage a regulated output voltage on the output terminal. The converter comprises a power transistor and the control device comprises a pilot circuit suitable for determining the period of switched-on time and the period of switched-off time of said power transistor and control means coupled to said pilot circuits and with said converter and which are capable of prolonging said period of switched-on time of the power transistor at the instants of time in which the alternating network voltage substantially assumes the value zero.

A method manages lamp fault conditions in electronic ballasts for one or more gas discharge lamps. The method for fault management of electronic ballast for at least one gas discharge lamp includes the steps of: preheating the lamp filaments applying a low current for a predetermined time; igniting the lamp by increasing at a predetermined rate the voltage applied up to a predetermined strike value; monitoring the lamp current; repeating the steps of igniting the lamp and monitoring the lamp current for a predetermined numbers of times if the lamp current is over a predetermined threshold; and powering the lamp at normal operating conditions.

Fault management method for electronic ballast

Boost capacitor layout

A circuit to control the supply of a reactive load, for supplying variable quantities of energy to the load in a predetermined manner is included in a system. The system also includes reactive components which are connected to the load by way of a controllable electronic switch and which form a resonant circuit with the load when the electronic switch is closed. Further, the system includes a circuit for activating the electronic switch, and a control unit which coordinates the operation of the controlled supply circuit and of the activation circuit in accordance with a predetermined program. The system enables the load to be driven with a particularly low power dissipated.

System for driving a reactive load

A current control method controls current for drive systems of multi-phase brushless motors, in particular at phase switching, wherein the motor coils coupled to a common node are driven by applying a respective drive voltage to the free end of each coil via corresponding power stages. The method comprises switching the current flow from one phase to the next in the direction of rotation of the motor at the phase switch, thereby forcing the unaffected one of said coils by the phase switch into a state of high impedance. Advantageously, the decreasing rate of the current in the coil unaffected by the phase switch can be twice as high as the decreasing rate of the current in the phase being switched from.

Control method of the current flow in driver systems for brushless motors, particularly during the switching phase

The power supply device includes a DC-DC converter circuit having a power switch and a driving stage. The driving stage has a compensation terminal on which a compensation voltage is present, and which receives a biasing current. The driving stage includes a control circuit having an output terminal connected to a control terminal of the power switch and disconnection-detecting circuitry connected to the compensation terminal and generating a signal for permanent turning-off of the power switch when the biasing current drops below a current-threshold value. The driving stage moreover includes over-voltage detecting circuitry connected to the compensation terminal and generating a signal for temporary turning-off of the power switch when the compensation voltage exceeds a voltage-threshold value.

Switching mode power supply device with detection of malfunctioning

A write head is described having a switchable damping resistance coupled in parallel with an inductor. The damping resistance is decoupled from the inductor by rendering a transistor nonconductive when a direction of current in the inductor changes. The damping resistance is then coupled to the inductor before oscillations begin in the current in the inductor. The decoupling of the damping resistor eliminates power dissipation in the damping resistor during a change in the direction of current in the inductor.

Write head with switchable impedance and method for operating same

A method for testing a programmable, nonvolatile memory including a matrix of memory cells is provided. A plurality of memory cells are programmed. The programmed memory cells are addressed in succession to identify a lowest of threshold voltage levels. The addressing for each memory location includes applying a selection voltage that is lower than the lowest threshold voltage level corresponding to a memory location currently being addressed. The bits are read from the programmed memory cells for the memory location currently being addressed. The reading is repeated while progressively changing the selection voltage supplied to the word line corresponding to the memory location currently being addressed until it is detected that at least one of the bits of the memory location currently being addressed has switched from a first logic level corresponding to a reading of a programmed memory cell to a second logic level corresponding to a reading of a non-programmed memory cell. The low threshold voltage level is compared in the memory location currently being addressed as determined in the reading with a stored value corresponding to the lowest of the low threshold voltages of the memory locations previously addressed.

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Udine, Italy

Albino Pidutti