Sgs-thomson Microelectronics S.r.l.

Stmicroelectronics S.r.l.

Stmicroelectronics Gmbh

Marelli Autronica S.p.a.

Thomson Microelectronics

Massimiliano Brambilla

Giampietro Maggioni

Paolo Menegoli

Vanni Poletto

Ezio Galbiati

Carlo Vertemara

Marco Morelli

Michele Berto Boscolo

Maurizio Nessi

Giampaolo Lombreschi

A method for detecting the position of a rotor of a DC motor with N phases having a plurality of windings, comprising the steps of connecting two of the windings between first and second prefixed voltages through to a first current path for a prefixed time, allowing the current stored in the two windings to discharge through a second current path; comparing the voltage across one of the two windings with a reference voltage and providing a control signal when the voltage is smaller in absolute value than the reference voltage, performing the above steps for each of the winding pairs of the motor; detecting the position of the rotor on the basis of the control signals obtained.

Method for detecting the position of a rotor of a DC motor and related circuit

A control circuit providing a driving current to a voice coil motor to position a reading and writing head of a disk memory system is described. The circuit comprises a first and a second class AB amplifiers the outputs of which are connected to the terminals of a first resistor in series with the voice coil motor so that a current passes through the voice coil motor and through the first resistor. The circuit comprises a sense amplifier the input terminals of which are coupled with the terminals of said first resistor, a device at the input of which is present a signal which is a sum of an external signal and of an output signal of the sense amplifier. The first amplifier and the second amplifier being driven in inverted phase by an output signal produced by the device. The circuit comprises means for inserting a second resistor in series with the first resistor so that said current passes through the series of said first and said second resistors and so that said sense amplifier has the input terminals coupled with the terminals of said series of resistors.

Driving circuit for a voice coil motor and driving method thereof

A method for starting a polyphase DC motor having a rotor. The position of the rotor is detected by initiating current in each of the phases of the motor and measuring a time period between the initiation of current in the coil and an instant when the current exceeds a threshold current. The phase in which the current reaches the threshold in the shortest amount of time is the phase closest to the position of the rotor. A phase closest to the position of the rotor is identified in each of an odd number of trials, and a starting phase is selected as the phase identified in the majority of trials. The motor is started by providing current to the starting phase.

Statistical phase detection and go start-up algorithm

A drive circuit fault detection device comprising a discriminating circuit generating a digital signal, the level of which indicates a fault; and an identifying circuit generating a binary-coded signal indicating the type of fault, i.e. ground shorting of the drive circuit or an open load. The discriminating circuit comprises a resistive network connected to the output of the drive circuit, for generating a voltage indicating correct connection of the load or a fault on the drive circuit and a comparator for comparing the generated voltage with a reference voltage and supplying the digital signal at its output. The identifying circuit comprises a current mirror circuit generating an output voltage having two different logic levels in the event of short circuiting or an open load, respectively, and a combination circuit for generating the binary-coded output signal.

Drive circuit fault detection drive

An electronic circuit for controlling an analog quartz clock, particularly for installation in automobiles, has first and second counters for generating control pulses at different rates according to whether the clock is to be operated in a normal mode, or a time-setting mode. In addition, a single 11-bit counter allows 'fast' or 'slow' resetting of the time by a single push button.

Counter circuit for controlling the operation of a quartz clock with

An inductive load drive device which has a switch defining an output terminal connectable to an inductive load between the output terminal and a reference potential line is provided. A first current recirculating branch is connectable parallel to the load and a control opens and closes the switch so that the load is supplied with current rising to a first predetermined value in a first increasing phase and falling to a second predetermined value in a first recirculating phase. The device detects a short-circuit between the output terminal of the control device and the reference potential line with a first current sensor for detecting current flow in the first recirculating branch during the first recirculating phase. A fault signaling circuit connected to the first current sensor produces a short-circuit signal in the absence of current in the first recirculating branch during the first recirculating phase.

Circuit for detecting short-circuiting of inductive load drive devices

A circuit comprising a switch series connected to a load; a first and second current recirculating branch alternately connectable parallel to the load, for reducing the current in the same; and a logic control unit for opening and closing the switch and recirculating branches, so that the load is supplied with a current rising to a peak value and then falling rapidly to and oscillating about a lower hold value; a transistor being provided for reducing the voltage supplied to the load by the first recirculating branch at the end of the fast fall phase, so as to eliminate uncontrollable operating zones and prevent the load current from falling below the hold value.

Inductive load drive circuit, particularly for fuel injections

The generator of reference voltage comprises a first current generator suitable for generating a current that varies linearly with the supply voltage, a first voltage generator suitable for generating a constant voltage with zero thermal drift, a second current generator suitable for generating a current dependent on the voltage with zero thermal drift, a second voltage generator suitable for generating a voltage with given thermal drift, a third current generator suitable for generating a current dependent on the voltage with given thermal drift and means for combining the three currents together so as to produce across an output resistance an output voltage having a value equal to the product of the output resistance by the first and third current, divided by the second current.

Generator of reference voltage that varies with temperature having given

The generator comprises a first generator of voltage with thermal drift of zero, a second generator of voltage with given thermal drift, first means for applying a given load to the voltage generated by the first generator, second means for applying a given load to the voltage generated by the second generator, subtracting means for subtracting one from the other the loaded voltages generated by said first and second generator of voltage.

Reference voltage generator with programmable thermal drift

This voltage reference circuit has high thermal stability and minimal bulk and comprises a transistor defining a base-emitter junction having a voltage drop which varies in a non-linear manner as a function of temperature and resistors connected in series to the junction, the junction and the resistors being interposed between a ground line and the output terminal. A compensation transistor generates a compensation current which varies as a function of temperature so as to produce a voltage drop with a behavior substantially opposite to the previous voltage drop upon reaching the switching on temperature of the transistor.

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Sesto San Giovanni, Italy

Massimiliano Brambilla