Abstract: A data storage device is disclosed comprising a head actuated over a disk, and a spindle motor configured to rotate the disk, wherein the spindle motor comprises a plurality of windings. The windings of the spindle motor are commutated based on a commutation sequence while applying a driving voltage to each winding, wherein the driving voltage comprises an operating polarity during normal operation. When a supply voltage falls below a threshold while the spindle motor is rotating the disk, the spindle motor is configured into a power generator by at least reversing the polarity of the driving voltage for an interval and then reversing the polarity of the driving voltage back to the operating polarity.

Abstract: A data storage device is disclosed comprising a spindle motor configured to rotate a disk, wherein the spindle motor comprises a plurality of windings. The windings are commutated based on a commutation sequence while applying a driving voltage to each winding, wherein the driving voltage comprises an operating amplitude during normal operation. When a supply voltage falls below a threshold, the spindle motor is configured into a power generator by at least reducing the amplitude of the driving voltage to substantially zero and then incrementally increasing the amplitude of the driving voltage by at least two steps toward the operating amplitude.

Abstract: A data storage device is disclosed comprising a head actuated over a disk, and a spindle motor configured to rotate the disk. A speed of the spindle motor is sampled, and an error signal is generated based on a difference between the sampled speed and a target speed. A sliding mode control signal for controlling a speed of the spindle motor is generated based on a first non-zero gain when the error signal is greater than zero and less than a first positive threshold, and a second non-zero gain when the error signal is greater than the first positive threshold.

Abstract: A data storage device is disclosed comprising a spindle motor configured to rotate a disk, wherein the spindle motor comprises a plurality of windings. The windings are commutated based on a commutation sequence while applying a driving voltage to each winding, wherein the driving voltage comprises an operating amplitude during normal operation. When a supply voltage falls below a threshold, the spindle motor is configured into a power generator by at least reducing the amplitude of the driving voltage to substantially zero and then incrementally increasing the amplitude of the driving voltage by at least two steps toward the operating amplitude.

Abstract: A data storage device is disclosed comprising a head actuated over a disk, and a spindle motor configured to rotate the disk. A speed of the spindle motor is sampled, and an error signal is generated based on a difference between the sampled speed and a target speed. A sliding mode control signal for controlling a speed of the spindle motor is generated based on a first non-zero gain when the error signal is greater than zero and less than a first positive threshold, and a second non-zero gain when the error signal is greater than the first positive threshold.

Abstract: A data storage device is disclosed comprising a disk comprising timing data, a spindle motor configured to rotate the disk, wherein the spindle motor comprises a plurality of windings, and a head actuated over the disk. A phase of a commutation controller is initialized based on the timing data on the disk, and a commutation sequence of the commutation controller is driven based on the timing data on the disk, wherein the commutation controller is configured to commutate the windings based on the commutation sequence. The phase of the commutation controller is re-initialized based on the timing data on the disk, thereby compensating for a cumulative phase error when driving the commutation sequence based on the timing data on the disk.

Abstract: A data storage device is disclosed comprising a non-volatile memory powered by a supply voltage. The supply voltage is compared to a power loss threshold, and when the supply voltage falls below the power loss threshold, a power loss event is detected and an emergency operation is executed. The power loss threshold is decreased, and after an interval the power loss threshold is increased.

Abstract: A data storage device is disclosed comprising a head actuated over a disk, and a spindle motor configured to rotate the disk, wherein the spindle motor comprises a plurality of windings. A commutation controller is configured to commutate the windings based on a commutation sequence driven by an oscillator. A rotation phase of the spindle motor is measured, and a phase error is generated based on the measured rotation phase of the spindle motor and a phase of the commutation sequence, wherein a frequency of the oscillator is adjusted based on the phase error.

Abstract: A data storage device is disclosed comprising a non-volatile memory. A supply voltage for powering the non-volatile memory is sampled to generate supply voltage samples. A power loss threshold is adjusted based on the supply voltage samples, and a power loss event is detected based on the power loss threshold and the supply voltage, wherein an emergency operation is executed when the power loss event is detected.

Abstract: A data storage device is disclosed comprising a head actuated over a disk, and a spindle motor configured to rotate the disk, wherein the spindle motor comprises a plurality of windings. A commutation controller is configured to commutate the windings based on a commutation sequence. Compensation values are generated based on: A1 sin ?1t+B1 cos ?lt where A1 and B1 are adaptable coefficients and ?1 represents a first frequency based on a first mechanical parameter of the spindle motor. The compensation values are used to drive the commutation sequence of the commutation controller.

Abstract: Determination of when an electronic device such as a data storage device (DSD) is falling. An input is received indicating an acceleration of the electronic device during a time period. A classifier function is calculated using the input and it is determined whether the electronic device is falling based on a calculated value of the classifier function. During a calibration process, acceleration values are recorded representing a plurality of actual falls and a plurality of false falls of the electronic device. Weight values are set for a weighted classifier function using the recorded acceleration values and the weighted classifier function is stored in a memory of the electronic device.

Abstract: Detecting an impact of an electronic device, such as a data storage device (DSD). An acceleration input is received indicating an acceleration of the electronic device and it is determined whether an acceleration change value based on the acceleration input is greater than an absolute threshold. If so, an acceleration change ratio is calculated using the acceleration change value and an average of acceleration change values. The acceleration change ratio is compared to a relative threshold and it is determined that an impact of the electronic device has been detected if the acceleration change ratio is greater than the relative threshold.