Abstract: Various illustrative aspects are directed to a data storage device comprising one or more disks; an actuator arm assembly comprising one or more actuator arms, and configured to position the one or more actuator arms over disk surfaces of the one or more disks; one or more fine actuators, disposed on the one or more actuator arms; and one or more processing devices. The one or more processing devices are configured to: output a driver current to the one or more fine actuators, wherein the one or more processing devices are configured to rate limit a rise of the driver current over time during an activation of the driver current to within a selected rate limit of current rise over time.

Abstract: A data storage device is disclosed comprising a plurality of disks each comprising a top disk surface and a bottom disk surface. A plurality of inner actuator arms each comprise a first inner fine actuator configured to actuate a top head over one of the top disk surfaces and a second inner fine actuator configured to actuate a bottom head over one of the bottom disk surfaces. A first outer actuator arm comprises a first outer fine actuator configure to actuate a top head over a top disk surface of a top disk, and a second outer actuator arm comprises a second outer fine actuator configured to actuate a bottom head over a bottom disk surface of a bottom disk, wherein the inner fine actuators are controlled independent from the outer fine actuators.

Abstract: A data storage device is disclosed comprising a plurality of disks each comprising a top disk surface and a bottom disk surface. A plurality of inner actuator arms each comprise a first inner fine actuator configured to actuate a top head over one of the top disk surfaces and a second inner fine actuator configured to actuate a bottom head over one of the bottom disk surfaces. A first outer actuator arm comprises a first outer fine actuator configure to actuate a top head over a top disk surface of a top disk, and a second outer actuator arm comprises a second outer fine actuator configured to actuate a bottom head over a bottom disk surface of a bottom disk, wherein the inner fine actuators are controlled independent from the outer fine actuators.

Abstract: A data storage device is disclosed comprising a voice coil motor (VCM) configured to actuate a head over a disk. The data storage device further comprises control circuitry comprising a digital current control loop including a windowed delta-sigma analog-to-digital converter (ADC) configured to control the VCM. A vibration of the data storage device is measured, and at least one of a gain or a window of the windowed delta-sigma ADC is configured based on the measured vibration.

Abstract: A data storage device is disclosed comprising a voice coil motor (VCM) configured to actuate a head over a disk. The data storage device further comprises control circuitry comprising a digital current control loop including a windowed delta-sigma analog-to-digital converter (ADC) configured to control the VCM. A vibration of the data storage device is measured, and at least one of a gain or a window of the windowed delta-sigma ADC is configured based on the measured vibration.

Abstract: A data storage device is disclosed comprising a head actuated over a disk, and a spindle motor configured to rotate the disk. A pulse width modulated (PWM) control signal is generated having a frequency based on a PWM clock, the spindle motor is controlled using the PWM control signal, and a frequency of the PWM clock is swung between a minimum frequency and a maximum frequency at a swing rate.

Abstract: A data storage device is disclosed comprising a head actuated over a disk, and a spindle motor configured to rotate the disk. A pulse width modulated (PWM) control signal is generated having a frequency based on a PWM clock, the spindle motor is controlled using the PWM control signal, and a frequency of the PWM clock is swung between a minimum frequency and a maximum frequency at a swing rate.

Abstract: A data storage device is disclosed comprising a first actuator configured to actuate a head over a disk, a second actuator configured to rotate the disk, a first control circuit configured to generate a servo command, and a second control circuit configured to receive the servo command from the first control circuit, control the first actuator or the second actuator using the servo command, and override the servo command to avoid an overcurrent condition.

Abstract: A data storage device is disclosed comprising a disk comprising servo data, and an actuator configured to actuate a head radially over the disk. The disk drive further comprises control circuitry comprising a servo controller and a driver circuit comprising an accumulator, wherein the servo controller is configured to generate digital control values based on the servo data and transmit the digital control values over a serial interface to the drive circuit. The accumulator is initialized based on a first digital control value received over the serial interface during a first servo interval, and then the accumulator is adjusted based on a second digital control value received over the serial interface during a second servo interval. An analog control signal is generated based on an output of the accumulator, and the analog control signal is applied to the actuator.

Abstract: A data storage device is disclosed comprising a head actuated over a disk, and a spindle motor configured to rotate the disk. A first driving voltage is applied across a first and second windings of the spindle motor connected in series while measuring a first mutual inductance voltage across a third winding, wherein the first driving voltage comprises a first amplitude and a first polarity. A second driving voltage is applied across the first and second winding connected in series while measuring a second mutual inductance voltage across the third winding, wherein the second driving voltage comprises the first amplitude and a second polarity opposite the first polarity. The first measured mutual inductance voltage and the second measured mutual inductance voltage are combined to generate a first mutual inductance signal, and an angular position of the spindle motor is estimated based on the first mutual inductance signal.

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. During a power failure the head is unloaded by generating a periodic signal, shorting the windings of the spindle motor based on the periodic signal in order to generate a power voltage, and adjusting the periodic signal based on an amplitude of the power voltage.

Abstract: A data storage device is disclosed comprising a spindle motor configured to rotate a disk, and a first voice coil motor (VCM) configured to actuate a head over the disk. During at least fifty percent of a seek of the head over the disk, a spindle control signal is generated based on a continuous function of a current flowing through the first VCM, and the spindle control signal is applied to the spindle motor.

Abstract: A data storage device is disclosed comprising a disk comprising servo data, and an actuator configured to actuate a head over the disk. A servo controller is configured to generate digital control values at a first sample rate based on the servo data and transmit the digital control values over a serial interface to a driver circuit. The driver circuit is configured to generate predictive oversampled control values at a second sample rate higher than the first sample rate based on at least two of the digital control values received from the servo controller, apply the predictive oversampled control values to a digital-to-analog converter (DAC) to generate an analog control signal, and apply the analog control signal to the actuator.

Abstract: A data storage device is disclosed comprising a voice coil motor (VCM) configured to actuate a head over a disk. The head is used to read data recorded on the disk to generate a read signal, and the read signal is processed to generate a current command signal at a servo sample rate having a servo sample interval. A current flowing through the VCM is detected, and a current error signal is generated based on a difference between the current command signal and the detected current flowing through the VCM. An analog command signal is generated based on the current error signal, and the analog command signal is applied to the VCM. A saturation in the analog command signal is detected, and a first deglitch window is generated during which the saturation detection is disabled, wherein the first deglitch window is programmed relative to the servo sample interval.

Abstract: A current balancing circuit is disclosed comprising a first current detector configured to measure a first current flowing from a first supply voltage to a first load, and a second current detector configured to measure a second current flowing through an inductor from a second supply voltage to the first load. The first current is compared to a first threshold to generate an error signal, and the error signal is amplified by a gain to generate a second threshold. When the first current is above the first threshold and the second current is below the second threshold, a first switch is controlled to connect a first end of the inductor to the second supply voltage. When the second current is above the second threshold, a second switch is controlled to connect the first end of the inductor to a current sink.

Abstract: A data storage device is disclosed comprising a first voice coil motor (VCM) comprising a first voice coil, and a second VCM comprising a second voice coil. The first VCM and the second VCM are unloaded during a power failure by measuring a first velocity and a first position of the first VCM and measuring a second velocity and a second position of the second VCM. A BEMF voltage generated by a spindle motor is used to generate a first brake voltage based on the first velocity and the first position, and the BEMF voltage is used to generate a second brake voltage based on the second velocity and the second position. The first brake voltage is applied to the first voice coil, and the second brake voltage is applied to the second voice coil.

Abstract: Analog-to-digital conversion circuitry for generating a digital output signal is disclosed comprising a sample-and-hold circuit comprising an adjustable sample capacitor for coupling to an analog input signal during a sample phase, and an analog-to-digital converter (ADC) coupled to an output of the sample-and-hold circuit during a hold phase. In order to compensate in real-time for an increase in an amplitude of the input signal, a capacitance of the sample capacitor is decreased by an attenuation factor, and an output of the ADC is multiplied by an inverse of the attenuation factor to generate the digital output signal.

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 stator, a rotor, and a plurality of windings. The data storage device further comprises control circuitry comprising a spindle motor driver comprising a plurality of switches including a first switch and a second switch configured to commutate the windings. A current flowing through the first switch is measured for a first part of an electrical cycle of the spindle motor. The measured current is processed to generate an estimated current flowing through the second switch during a second part of the electrical cycle of the spindle motor, wherein the first part of the electrical cycle is different from the second part of the electrical cycle.

Abstract: A data storage device is disclosed comprising a disk, a head, a shock sensor, and an oscillator circuit responsive to the shock sensor and configured to generate an oscillating signal using positive feedback. A resonant frequency of the shock sensor is detected based on the oscillating signal. A physical shock affecting the head actuated over the disk is detected based on a response of the shock sensor to the physical shock and based on the detected resonant frequency of the shock sensor.

Abstract: A data storage device is disclosed comprising a voice coil motor (VCM) and a secondary actuator configured to actuate a head over a disk. A control signal is applied to the secondary actuator while processing a sensor signal generated by the secondary actuator. A vibration signal is generated based on the sensor signal, wherein the vibration signal has a cut-off frequency between ten percent and ninety percent of a bandwidth of a control loop for controlling the secondary actuator.