Stmicroelectronics S.r.l.

Luigi Eugenio Garbelli

Salvatore Portaluri

Alessandro Savo

Giuseppe Luciano

Maurizio Nessi

Luca Schillaci

Giorgio Sciacca

The method is for controlling a voice coil motor which drives a mechanical arm via a control circuit which sets the output nodes, to which the motor is connected, in a high impedance state for a certain time interval. The method and circuit detect the back electromotive force induced on the motor winding during the time interval, and deliver current pulses for driving the motor. The circuit compares the detected back electromotive force with a certain target value and regulates the amplitude of the driving current pulses as a function of the difference between the detected value of the back electromotive force and a voltage signal representing the desired speed of the arm, according to a pre-established function. A preferred embodiment includes such a function being a pre-established saturated linear characteristic with an offset value.

Method of driving with high precision a voice coil motor and related architecture

The monitoring of multiple supply voltages of an integrated circuit is done using a single external capacitor connected to a pin of the integrated circuit. Part of the multiple supply voltages are externally generated and part are internally generated. The internally generated supply voltages may include different voltages with different signs. A logic signal indicating that all the supply voltages have reached pre-established values before enabling functioning of the integrated circuit is generated after an initial soft start phase of the turn-on process.

Method and circuit of soft start and of power monitor for IC with multiple supplies

A driver circuit includes a half-bridge output stage including two transistors with a common terminal for connection as the driver output to a coil of a DC motor. Two amplifiers drive the transistors in the push-pull operation and two capacitors are connected between the driver output and one input of a respective amplifier to form feedback loops for controlling the output slew-rate. Two current generators are selectively connected to an input of either of the amplifiers through respective pairs of switches. A commutation sequencer turns on and off the switches according to a commutation program. Comparators are connected to the drive output for detecting predetermined output voltage conditions and providing the commutation sequencer with signals for conditioning the commutation program as a function of the detected voltage conditions.

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Mapello, Italy

Luigi Eugenio Garbelli