Stmicroelectronics S.r.l.

Stefano Beria

Albino Pidutti

Claudio Adragna

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

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 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.

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Pavia, Italy

Stefano Beria