Stmicroelectronics S.r.l.

Sgs-thomson Microelectronics S.r.l.

Stmicroelectronics Gmbh

Maurizio Nessi

Ezio Galbiati

Luca Schillaci

Giona Fucili

Marcello Leone

Annamaria Rossi

Giorgio Sciacca

Frederic Bonvin

Agostino Mirabelli

Rinaldo Castello

Salvatore Portaluri

Giacomino Bollati

Massimiliano Brambilla

Alessandro Savo

Alberto Salina

Pierandrea Savo

Luigi Eugenio Garbelli

Francesco Chrappan

Alessandro Scrivani

Simone Silvestri

Marco Palestra

An embodiment of a motor controller includes first and second supply nodes, a motor-coil node, an isolator, a motor driver, and a motor position signal generator. The isolator is coupled between the first and second supply nodes, and the motor driver is coupled to the second supply node and to the motor-coil node. The motor position signal generator is coupled to the isolator and is operable to generate, in response to the isolator, a motor-position signal that is related to a position of a motor having at least one coil coupled to the motor-coil node. By generating the motor-position signal in response to the isolator, the motor controller or another circuit may determine the at-rest or low-speed position of a motor without using an external coil-current-sense circuit.

Determining a position of a motor using an on-chip component

A current sensing circuit for a pulse width modulation (PWM) application may include first and second input terminals to be coupled to ends of a sensing resistance, an output terminal, and first and second internal circuit nodes. The current sensing circuit further may include an input block comprising a first transconductance amplifier to be coupled to a supply voltage. The first transconductance amplifier may be coupled to the first and second input terminals and to the first and second internal circuit nodes. The current sensing circuit may also include an amplifier block comprising an amplifier to be coupled to a reference voltage, and coupled to the first and second internal circuit nodes and the output terminal, and a feedback block comprising a second transconductance amplifier to be coupled to the supply voltage and being coupled to the output terminal and the first and second internal circuit nodes. The input block may further include a third transconductance amplifier coupled in cascade to the first transconductance amplifier and to the first and second input terminals.

Current sensing circuit for PWM applications with pulse width modulation and corresponding current process

An apparatus is provided for powering at least one electric motor. The apparatus includes at least one driving device for driving the electric motor, a supply path positioned between a supply voltage generator and the at least one driving device, a first circuit, a control device, and a protection device for protecting against over-voltages. The first circuit is inserted in the supply path to enable and prevent the powering of the at least one driving device, and the control device controls at least the first circuit. The protection device includes a second circuit for detecting a current that flows in the supply path from the at least one driving device to the supply voltage generator, and a third circuit for selectively absorbing the current that is detected.

Apparatus for powering electric motors

A circuit estimates speed of an electromagnetic actuator associated with a reading head of a disk storage unit and a digital controller. The circuit includes first and second supply terminals and an output terminal, with the first supply terminal being connected to the electromagnetic actuator. A measuring resistor is connected to the second supply terminal, and is connected in series with the electromagnetic actuator for measuring a current which passes therethrough when a supply voltage is applied between the first and second supply terminals. An adder has an output connected to the output terminal for providing an output voltage, a first input is connected to the first supply terminal, and a second input is connected to the second supply terminal. An adjustable-gain amplifier is connected between the measuring resistor and the second input of the adder for transferring the supply voltage and a voltage across the measuring resistor to the adder. A determination circuit is connected to the adjustable-gain amplifier for determining a gain thereof. The determination circuit includes a coarse setting circuit and a fine calibration circuit controlled by the digital controller.

Circuit for estimating the speed of an electromagnetic actuator

Tracking analog-to-digital converter

A circuit for the speed recovery of a direct current motor includes an output stage, output stage having a first pair of transistors, a second pair of transistors, and means a first circuit configured to detect a current circulating in the motor. The output stage further includes a second circuit configured to, activate the second pair transistors for a determined first time period so as to short-circuit the motor, and, at the end of the first time period, unbalance the output stage so as to force a maximum current to circulate for a determined second time period as a function of a value detected by the first circuit during the first time period, so as to stop the motor.

Circuit for the speed recovery of a direct current motor and method using said 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 positioning system for a read/write head of a disk drive includes a rotatable data disk, a read/write head movable over the disk, a voice coil motor (VCM) connected to the head and a source of digital position signals. A control circuit includes means for generating a VCM control current, a sensor for sensing the VCM current and an amplifier having an inverting input connected to a reference voltage source through a resistor and to a sensor output, a non-inverting input connected to the source of digital position signals through a DAC and an output connected to an input of the drive means.

Control circuit for a hard disk drive head

A feedback control circuit is for the current in a load formed by a winding in series with a current sensing resistor, coupled to a full-bridge output stage, an amplifier coupled to the terminals of the sensing resistor, and a controller fed with the output of the amplifier and with a voltage reference and producing a correction signal. The circuit has a PWM converter for generating a pair of control signals. The PWM converter includes an up/down counter producing a count value and logic circuitry that produces the twos-complement of the correction signal. A pair of registers are coupled to the outputs of the controller and of the logic circuitry. A first comparator coupled to the outputs of the counter and of the first register produces the first control signal, if the count signal exceeds the value stored in the first register. A second comparator coupled to the counter and to the second register produces the second control signal, if the count signal overcomes the value stored in the second register.

Analog/digital PWM control circuit of a winding

A method drives a three-phase motor having first, second, and third coils. The method electrically connects the first coil to a first voltage reference and the second coil to a second voltage reference while leaving the other coil floating during a first driving phase. During a second driving phase, the first coil is electrically connected to the first voltage reference and the third coil is electrically connected to the second voltage reference while the second coil is left floating. During a transition phase that immediately follows the fast driving phase and immediately precedes the second driving phase, the second coil is electrically connected alternately to the first and second voltage references. By alternately connecting the second coil to the first second voltage references and during the transition phase, the method causes the current through the second coil to reduce to zero at a slower rate than prior methods. This enables the variations of the currents that the two phases in commutation, the second and third coils, to happen in a way that maintains their sum constant, as much as possible. This reduces the torque ripple during the phase commutations and its accompanying acoustic noise.

Silent phase commutation in a three-phase brushless DC motor

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.

Driver circuit for a polyphase DC motor with minimized voltage spikes

A successive approximation register has a serial input and output comprises a chain of logic circuits of the bistable type which have selectable input terminals feedback connected by a storage and control element and logic gate circuits of the OR-type, and connected to a serial line through respective internal switches communicating the serial line to input terminals of the logic circuits in said chain, the serial line forming an input to a flip-flop of the D type which is the output element of the register.

Successive approximation shift register with reduced latency

The operation of externally connected output power transistors of a class AB amplifier is controlled without employing any external sensing resistance of the output current by driving an externally connected power transistor through a level shifting buffer and employing a limiting network composed of an integrated transistor driven by the output of a signal amplifying stage and a resistance connected in series with its drain. The buffer stage shifts the level of the driving signal of the external power transistor by a value equal to the threshold voltage of the integrated transistor of the limiting network thus ensuring the turn-off of the external power transistor under quiescent conditions.

Integrated unit gain output stage

A BEMF detector and method detect the BEMF of a three-phase motor using a fully differential detection system. The motor has a first coil coupled between a first coil tap and a center tap, a second coil coupled between a second coil tap and the center tap, and a third coil coupled between a third coil tap and the center tap. The BEMF detector includes a differential amplifier having first and second inputs and first and second outputs, with the first input being coupled to one of the coil taps and the second input being coupled to the center tap. The BEMF detector also includes a comparator having first and second inputs coupled respectively to the first and second outputs of the differential amplifier and an output at which a BEMF signal is produced that is related to the BEMF of the motor. The differential amplifier may be part of an anti-alias filter structured to fix to a known stable value a common mode at the outputs of the differential amplifier. The BEMF detector also may include one or more fully differential filters positioned between the differential amplifier and the comparator to reduce noise and smooth the BEMF signal output by the comparator. One of the filters can be a linear phase, switched capacitor filter with a stable cutoff frequency.

Growing community of inventors

Como, Italy

Maurizio Nessi