Western Digital Technologies, Inc.

Other

3D Systems, Inc.

Timothy A Ferris

Jaesoo Byoun

Robert P Ryan

John R Agness

Raffi Codilian

Yanning Liu

Alain Chahwan

Brian A Johnson

Xin Ru Wang

Masahito Kobayashi

Duc T Phan

Brian Kenneth Tanner

Dean V Dang

Michael Troy Nicholls

Raymond J Bishop

Jianghong Ding

Mingying Gu

Erik Jesper Eklund

Alan P Rice

Joseph J Crowfoot

Arvind Chari

Michael A Everett

Jong Hyun Lee

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.

Data storage device detecting spindle motor position at increased resolution using mutual inductive sense

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.

Data storage device regulating BEMF power voltage during power failure

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.

Data storage device employing predictive oversampling for servo control

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.

Current balancing circuit for multiple supply voltage systems

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.

Data storage device employing smart braking to unload multiple voice coil motors

A method of tuning a notch filter in a data storage device (DSD) including the notch filter and a shock detection system includes: adjusting pulse width modulator (PWM) frequency settings of a spindle drive signal; detecting a maximum noise level of an output signal of the shock detection system while adjusting the PWM frequency settings; and selecting a notch filter frequency corresponding to a PWM frequency setting at which the maximum noise level of the output signal of the shock detection system is detected.

Shock sensor resonance detection for notch filter tuning

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.

Analog-to-digital conversion circuitry with real-time adjusted gain and resolution

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.

Data storage device measuring resonant frequency of a shock sensor by inserting the shock sensor into an oscillator circuit

A data storage device is disclosed comprising a disk, a head, and a shock sensor comprising a first terminal and a second terminal. A first bias signal is applied signal to the first terminal of the shock sensor and a second bias signal is applied to the second terminal of the shock sensor. An oscillating signal is generated by increasing the first bias signal and decreasing the second bias signal, and 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.

Data storage device measuring resonant frequency of a shock sensor by applying differential excitation and measuring oscillation

A power control module including first port for receiving supply voltage from host power supply, second port for providing output voltage to power one or more data storage device components, isolation circuit coupled to first and second ports, driver including output coupled to control terminal of isolation circuit, voltage booster including input for receiving supply voltage and output for providing boost voltage to supply terminal of driver, voltage limiter operable to limit boost voltage to a limited boost voltage, and control circuitry coupled to drive input and operable to cause the isolation circuit to be in closed state during normal operating mode by causing the driver to apply limited boost voltage to the control terminal of the isolation circuit, thereby enabling the isolation circuit to provide over-voltage protection to one or more data storage device components by limiting output voltage at second port to less than the limited boost voltage.

Power control module for data storage device

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 is a high-pass signal.

Data storage device concurrently controlling and sensing a secondary actuator for actuating a head over a disk

A data storage device is disclosed comprising a spindle motor configured to rotate a disk, wherein the spindle motor comprises a stator, a rotor, and a plurality of windings. The data storage device further comprises an isolation circuit configured to isolate the windings from a supply voltage, a head actuated over the disk, and 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. While driving the isolation circuit with a first calibration current, the first switch is driven with a second calibration current and a first current flowing through the first switch is measured. While driving the isolation circuit with the first calibration current, the second switch is driven with the second calibration current and a second current flowing through the second switch is measured.

Data storage device compensating for fabrication tolerances when measuring spindle motor current

A disk drive is disclosed comprising a disk, a spindle motor operable to rotate the disk, a head actuated over the disk, an interface operable to receive a host supply voltage, and a capacitor. The host supply voltage is used to charge the capacitor to a capacitor voltage higher than the host supply voltage. During a power failure, the host supply voltage stops charging the capacitor, and a motor supply voltage is generated from the spindle motor. The capacitor voltage is used to operate control circuitry, and when the capacitor voltage decays below the motor supply voltage, the motor supply voltage charges the capacitor.

Power failure management in disk drives

Self-heating integrated circuits are provided. In one embodiment, a self-heating integrated circuit comprises a drive circuit configured to drive a device and a controller configured to selectively operate the drive circuit in a first mode or a second mode. In the first mode, the controller is configured to operate the drive circuit to drive the device and, in the second mode, the controller is configured to operate the drive circuit to heat the integrated circuit to a target temperature.

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Mission Viejo, CA, United States of America

Timothy A Ferris