Western Digital Technologies, Inc.

Other

Jaesoo Byoun

Gaku Ikedo

Naoyuki Kagami

Hideaki Ito

Brian A Johnson

Timothy A Ferris

Brian Johnson

Hiroki Watanabe

Masahito Kobayashi

Yanning Liu

Brian Kenneth Tanner

Ryan P Mayo

Yasunori Fukuyama

A data storage device comprises a lead actuator that actuates a first read-write head over a first disk and a support actuator that actuates a second read-write head over a second disk. A spindle motor rotates the first and second disks. In response to an emergency power off (EPO) event, a processing device retracts and parks the actuators using an internal supply voltage generated from a back electromotive force (BEMF) voltage of the spindle motor, and brakes the spindle motor. The spindle motor is not braked until both the lead and support actuators have been retracted and parked.

Data storage device having dual actuators and method for emergency power off retract (EPOR) of dual actuators

Various illustrative aspects are directed to a data storage device comprising one or more disks, an actuator arm assembly comprising one or more disk heads and a voice coil motor (VCM), the VCM configured to operate in a PWM mode and a linear mode, and one or more processing devices configured to: seek the VCM towards a target track in the PWM mode; transition the VCM from the PWM mode to the linear mode, wherein the transitioning comprises switching an offset compensation value from a first offset compensation value to a second compensation offset value to compensate for a transition offset induced while transitioning the VCM from the PWM to the linear mode, wherein the first and the second offset compensation values correspond to the PWM and linear modes, respectively, and seek the VCM towards the target track in the linear mode for a linear mode time.

VCM PWM to linear mode transition offset optimization to improve PES

A data storage device has a closed loop extended park mode during spin down operation. A data storage device comprises a spindle motor configured to rotate one or more disks, and one or more processing devices. The one or more processing devices are configured to determine a value of current that is discharged from the spindle motor over time during a spin down of the spindle motor, and control a braking duty cycle for braking the spindle motor during the spin down such that the value of current discharged from the spindle motor over time does not exceed a selected current limit.

Data storage device with closed loop extended park mode during spin down operation

Various illustrative aspects are directed to a data storage device comprising one or more disks, an actuator arm assembly comprising a voice coil motor (VCM), the VCM configured to operate in a first mode and a second, different mode, wherein the first mode corresponds to at least a first and a second setting, and a control circuitry configured to cause the VCM to seek towards a target track in the first mode using the first setting for a first duration, control transition of the VCM from the first to the second setting in the first mode, cause the VCM to seek towards the target track using the second setting for a second duration, and control transition of the VCM from the first to a second mode, wherein controlling the transitioning comprises seeking the VCM toward the target track in the second mode for a third duration.

Optimize power, RTV, and coupled PES during seek operations

Various illustrative aspects are directed to a data storage device comprising a disk and a spindle motor configured to rotate the disk wherein the spindle motor is powered by a drive voltage generated in response to a host voltage. The data storage device includes a head configured to be actuated over the disk by a head actuator and control circuitry comprising an isolation field effect transistor (ISOFET) configured to prevent a reverse current from flowing from the drive voltage to the host voltage when the host voltage falls below a threshold. The control circuitry sets a turnoff current level at which the ISOFET is directed to turn off to prevent the reverse current from flowing determines a drain-source on resistance Rdson of the ISOFET, and calculates a voltage turnoff threshold at which the ISOFET is turned off from the turnoff current level and the determined Rdson.

Data storage device with smart ISOFET threshold voltage automatic tuning

A data storage device comprises a lead actuator that actuates a first read-write head over a first disk and a support actuator that actuates a second read-write head over a second disk. A spindle motor rotates the first and second disks. In response to an emergency power off (EPO) event, a processing device retracts and parks the actuators using an internal supply voltage generated from a back electromotive force (BEMF) voltage of the spindle motor, and egresses data from a volatile to a non-volatile semiconductor memory. Egress is throttled before the actuators are retracted and parked when the internal supply voltage falls to or below a first egress throttling threshold voltage. Egress is throttled after the actuators are retracted and parked when the internal supply voltage falls to or below a second egress throttling threshold voltage.

Data storage device having dual actuators and method for data egress throttling during emergency power off retract (EPOR)

Various illustrative aspects are directed to a data storage device comprising a first spindle motor configured to rotate one or more disks in a first stack of disks, a second spindle motor configured to rotate one or more disks in a second stack of disks, and one or more processing devices configured to detect back electromotive force (BEMF) voltages generated by the first spindle motor and the second spindle motor. In other aspects the one or more processing devices can control speeds of the first spindle motor and the second spindle motor based on the detected BEMF voltages.

Dual spindle motors and dual spindle motor control for data storage

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.

Data storage device with soft on-disk activation of fine actuators

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.

Data storage device independently driving outer and inner fine actuators

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.

Data storage device using windowed delta-sigma analog-to-digital converter in digital current control loop

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.

Data storage device with spread spectrum spindle motor control

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.

Data storage device capable of overriding a servo command to avoid an overcurrent condition

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.

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Irvine, CA, United States of America

Jaesoo Byoun