Abstract: A device for the change of the driving mode of an electromagnetic load from a first operating mode with pulse width modulation to a second operating mode that is linear by means of switching circuits. During a first operating mode, each of two outputs has a voltage value ranging from a first reference voltage to a second reference voltage. The device adapted to synchronize a change command signal from a first operating mode to a second operating mode of the electromagnetic load with the signal representative of the flow of current circulating within the load at substantially its average value and adapted to generate a first command signal in response to the synchronization.

Abstract: A device for the change of the driving mode of an electromagnetic load from a first operating mode with pulse width modulation to a second operating mode that is linear by means of switching circuits. During a first operating mode, each of two outputs has a voltage value ranging from a first reference voltage to a second reference voltage. The device adapted to synchronize a change command signal from a first operating mode to a second operating mode of the electromagnetic load with the signal representative of the flow of current circulating within the load at substantially its average value and adapted to generate a first command signal in response to the synchronization.

Abstract: A disk drive may include a housing, and a rotatable data storage disk and associated disk drive motor carried by the housing for rotating the rotatable data storage disk. The disk drive may also include a movable arm and associated arm drive motor carried by the housing for moving the arm adjacent to the rotatable data storage disk. Further, at least one read/write head may be carried by the arm, and a driving circuit may be included for the arm drive motor. The driving circuit may include at least one output stage connected to a power supply for driving the arm drive motor, at least one capacitor connected to the power supply, and an auxiliary pulse width modulation (PWM) control circuit connected to the at least one capacitor for driving the at least one output stage in a PWM mode after the power supply is switched off.

Abstract: A system for controlling and driving an electromagnetic actuator includes a unique operational amplifier in the regulation loop for driving the electromagnetic actuator and for monitoring, during different phases of operation, the current in the actuator and the back electromotive force. The new architecture allows for a considerable reduction of the area of integration of the system as a whole.

Abstract: The present invention relates to the positioning of the read/write transducer heads of an hard disk (HD) in a designated landing zone when requested or when the electrical power is removed from the drive. In particularly it relates to the detection of the back electromotive force (BEMF) of the motor involved in the positioning of the read/write transducer heads.

Abstract: A method for controlling an electromagnetic actuator having an arm connected thereto uses a circuit that temporarily places in a high impedance state output nodes connected to a winding of the electromagnetic actuator. A detected BEMF is compared with a lower threshold and an upper threshold. Current in the electromagnetic actuator is monitored and controlled. A current pulse is provided to the electromagnetic actuator based upon the comparison of the detected BEMF with the lower and upper thresholds. The respective amplitudes of successively provided current pulses having a same polarity are progressively increased, and an amplitude of a provided current pulse having a polarity opposite a polarity of a preceding current pulse is decreased. The amplitude of the driving current pulses provided to the winding of the electromagnetic actuator advantageously adapts automatically to varying frictional conditions, or to any other cause of variation of the mechanical load of the actuator.