Stmicroelectronics S.r.l.

Sgs-thomson Microelectronics S.r.l.

Politecnico Di Milano

Giuseppe Maiocchi

Ezio Galbiati

Michele Boscolo Berto

Michele Berto Boscolo

Maurizio Ricci

Marco Viti

Roberto Giorgio Bardelli

Roberto Oboe

Federico Marcassa

Andrea Barbieri

Luca Molinari

Giacomo Langfelder

Paolo Pascale

Federico Magni

Matteo Scorrano

Paolo Frigerio

An embodiment method includes rectifying a back electromotive force of a spindle motor in a hard disk drive and energizing a voice coil motor in the hard disk drive using the rectified back electromotive force of the spindle motor via a voice coil motor power stage to retract a head of the hard disk drive to a park position. The head is retracted by moving the head towards the park position during a first retract phase and retaining the head in the park position during a second retract phase by applying a bias voltage to the voice coil motor power stage during a bias interval of the second retract phase. The method also includes producing a saturation signal indicative of onset of saturation in the voice coil motor power stage and controlling the bias voltage during the second retract phase.

Method of operating hard disk drives and corresponding control circuit

Disclosed herein is a control system for a projection system, including a first subtractor receiving an input drive signal and a feedback signal and generating a first difference signal therefrom, the feedback signal being indicative of position of a quasi static micromirror of the projection system. A type-2 compensator receives the first difference signal and generates therefrom a first output signal. A derivative based controller receives the feedback signal and generates therefrom a second output signal. A second subtractor receives the first and second output signals and generates a second difference signal therefrom. The second difference signal serves to control a mirror driver of the projection system. A higher order resonance equalization circuit receives a pre-output signal from an analog front end of the projection system that is indicative of position of the quasi static micromirror, and generates the feedback signal therefrom.

Closed-loop position control of MEMS micromirrors

A method of controlling a half-bridge circuit includes receiving an analog feedback signal proportional to an output of the half-bridge circuit, comparing the received analog feedback signal with a threshold value, selecting a digital feedback signal based on a result of the comparing, comparing the digital feedback signal with a digital reference signal to generate a digital error signal, integrating the digital error signal to generate an integration error signal, downscaling the integral error signal to generate a downscaled integration signal, sampling the downscaled integration signal to generate a sampled integration signal, and generating pulsed signals from the sampled integration signal to provide an input to the half-bridge circuit.

Method of controlling a half-bridge circuit

A half-bridge control circuit comprises an input terminal, an output terminal for providing a pulsed signal to a half-bridge driver circuit configured to drive two electronic switches connected between two supply terminals, and a feedback terminal for receiving a feedback signal indicative of the instantaneous voltage value at a switching node between the two electronic switches. A selector circuit provides a digital feedback signal. A subtractor generates an error signal by subtracting the digital feedback signal from the reference signal. An integrator generates an integration signal by integrating the value of the error signal. A down-scale circuit generates a reduced resolution integration signal by discarding one or more least significant bits of the integration signal. A sampling circuit generates a sampled integration signal by sampling the reduced resolution integration signal. A pulse generator circuit generates the pulsed signal as a function of the sampled integration signal.

Half-bridge control circuit, related integrated circuit and half-bridge circuit

A method includes receiving an input digital signal and applying the input digital signal to digital filter processing with a corner frequency to produce a filtered output digital signal. The digital filter processing includes a set of multiplication operations using a set of filter multiplication coefficients. The set of multiplication operations is performed by alternately using a first set of approximate multiplication coefficients and a second set of approximate multiplication coefficients different from the first set of approximate multiplication coefficients. The approximate multiplication coefficients in the first set of approximate multiplication coefficients and the second set of approximate multiplication coefficients approximate multiplication coefficients in the set of filter multiplication coefficients as a function of negative power-of-two values. The alternating of multiplication operations results in digital filter processing with average corner frequency approximating the corner frequency.

Digital filtering method, corresponding circuit and device

A driver device coupled to a winding of an electro-mechanical actuator includes: a power stage driving the winding in a discontinuous mode by alternating conduction on-phases to off-phases, and a sensor circuit sensing a voltage across the winding in an off-phase, wherein, during such an off-phase the voltage across the winding includes a residual voltage which decays to zero. The power stage drives the winding from an on-phase to an off-phase by applying to the winding a reverse current pulse to invert the direction of flow of the current through the winding and produce an oscillation of the residual voltage, whereby the residual voltage includes a zero-crossing point after the current through the winding is exhausted. The sensor circuit senses the voltage across the winding at this zero-crossing point, whereby the voltage sensed across the winding at the zero-crossing point is indicative of the back electromotive force of the winding.

Method of detecting back electromotive force in electro-mechanical actuators, corresponding device and apparatus

A control unit is for a bridge circuit. The control unit may include a signal generator configured to generate first and second periodic drive signals for the bridge circuit, and determine a switch-on duration of the first and second periodic drive signals based upon a first digital data value having a first resolution. The control unit may include a controller configured to receive a second digital data value having a second resolution. The second resolution may be greater than the first resolution. The controller may be configured to generate the first digital data value so that, over periods of the first and second periodic drive signals, the first digital data value corresponds to an average of the second digital data value.

Control unit for a bridge circuit, and related method and integrated circuit

A power supply may include power generation circuits, each configured to drive a respective winding of a multiphase motor; converter circuits, each configured to generate a digital driving signal for a respective power generation circuit, and a memory configured to store a plurality of fast recirculation compensation values corresponding to combinations of the digital driving signals that would otherwise result in a fast recirculation condition. The power supply may also include a controller coupled to the memory and configured to determine when a given combination of the digital driving signals would otherwise result in a fast recirculation condition, and based upon the determination, substitute at least one corresponding fast recirculation compensation value for the given combination of the digital driving signals.

Power supply for multiphase motor providing recirculation compensation features and related methods

A switching controller of a poly-phase electric motor may generate, in a fully digital manner, a replica of the phase current and/or of the phase (star) voltage of one or more windings of the motor. The switching controller may use digital signals already available for driving the motor to reconstruct a replica of the phase current or the phase voltage, and thereby avoid the need for dedicated analog components for phase current or phase voltage determination.

Switching controller for electric motors and related method of controlling electric motors

A method of PWM regulating a motor through a half-bridge drive stage includes sampling the motor current to obtain sampled values during driving intervals or during current decay intervals, and comparing a last sampled value with a current threshold. The motor is coupled in a slow decay electrical path for the duration of a current decay interval if the last sampled value does not exceed the current threshold. Otherwise the motor is coupled in a fast decay electrical path for a portion of the duration of the current decay interval, and is coupled in the slow decay electrical path for a remaining part of the duration of the same current decay interval.

Method of PWM regulation of a continuous current electric motor

A management apparatus is described of a rotating motor and a load during power loss; the apparatus comprises a first switching circuit coupled with the rotating motor and a controller of said first switching circuit. The controller is configured to drive the first switching circuit so as to convert a back-electromotive force voltage developed in the rotating motor into a power supply voltage for the load. The first switching circuit is driven in accordance with a first duty cycle. The apparatus comprises a second switching circuit coupled with the load and driven in accordance with a second duty cycle. The controller is configured to vary said first and said second duty cycles to keep the power supply voltage for the load above or equal to a threshold voltage.

Management apparatus of a rotating motor and an annexed load during power loss

A method of preventing concurrent or quasi-concurrent commutations of a pair of phase shift modulation (PSM) drive signals of an output bridge stage driving an electrical load includes establishing a threshold level of a programmed current level to be transmitted though the electrical load. The method also includes, if the programmed current level is lower than the threshold level, enhancing a time offset between commutation edges of the pair of PSM drive signals by a minimum time.

Prevention of concurrent PWM or PSM commutations of power signals driving a voice coil motor (VCM) to reduce S/N ratio degradation of low level signal lines of a R/W head

A control apparatus for a supply device of a load, the supply device is of switching type and connected between a supply voltage and a reference voltage, the apparatus including a sigma-delta device having an input terminal at which is present a first digital signal and adapted to provide a pulse-density modulation signal at the output terminal; the sigma-delta device including a feedback circuit capable of sending to the input terminal of the sigma-delta device a second digital signal whose value depends on the value of the output signal, and the apparatus including a device capable of digitalizing the supply voltage and of providing a further digital signal. The feedback circuit includes a terminal capable of receiving the further digital signal, and the sigma-delta device having a gain such that the output digital signal is proportional to the inverse of the further digital signal.

Control apparatus for a load supply device

An integrated control and power driving system moves a read/write head carrying arm over the surface of a disk. The integrated control and power driving system is applicable to a spindle motor, a mass storage disk drive and a voice-coil motor, for example, and includes a first chip and a second chip. The first chip integrates the output power stages driving the motors, and has an interface for outputting feedback signals representing functioning conditions of the voice-coil motor and of the spindle motor, and for receiving digital control signals of the output power stages. The second chip integrates logic drive and control circuitries of the power stages and an interface for receiving the feedback signals output by the first chip, and for transmitting to the first chip the digital control signals.

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Capiago Intimiano, Italy

Giuseppe Maiocchi