Abstract: An apparatus for powering a voice coil motor retract circuit in a disk drive is disclosed. The apparatus allows a disk drive to power the voice coil motor retract circuit while also slowing the spinning disk. A DC-to-DC converter converts the back electromotive force from the spinning disk into voltage which drives the retract circuit. A feedback circuit controls the switching of the DC-to-DC converter based on the available voltage for performing the retract function. Importantly, the DC-to-DC converter allows the disk to be slowed while simultaneously providing power to the retract circuit. In one embodiment, the windings of the spindle motor are used as the inductor element in the DC-to-DC converter. The power MOSFETs associated with the spindle motor are used as the diode unit and the switch unit of the DC-to-DC converter. The power supply capacitor is used as the output capacitor of the DC-to-DC converter.

Abstract: A system provided for protecting a disk drive from impact damages. More specifically, a disk drive is provided that includes an accelerometer interconnected to a printed circuit board that detects free fall of the disk drive. In addition, the velocity of spinning disks of the disk drive is also monitored to assess changes in velocity thereof that may indicate the presence of a tumbling condition. Furthermore, the change in acceleration measured by the accelerometer is monitored to prevent false indications of free fall due to common vibrations. Thus an enhanced system is provided that protects disk drives from the effect of free falls under a wide variety of conditions and allowing for drops from shorter distances to be identified.

Abstract: A disk drive includes a rotatable storage disk, an actuator motor, a slider that magnetically interacts with the storage disk, and a drive circuitry. A portion of the slider moves between a first position wherein the slider does not contact the storage disk and a second position wherein the slider contacts the storage disk. The drive circuitry can detect when the position of the slider changes between these positions. In one embodiment, the drive circuitry monitors off-track movement of the slider to detect when the slider has moved between these positions. The drive circuitry can also current that is directed to the actuator motor that is used to compensate for off-track movement to detect when the slider moves between these positions. In yet another embodiment, the drive circuitry monitors a rotational velocity of the storage disk to detect approximately when the slider moves between these positions.

Abstract: A method is provided for identifying offsets of accelerometers integrated into hard disk drives. More specifically, often, disk drives employ accelerometers that constantly monitor the acceleration felt by the disk drive. Once the accelerations are less than a predetermined threshold, a free fall event is identified and an actuator arm that is generally positioned above the disk is placed in a safe location prior to impact. Accelerometers must be calibrated prior to use such that their inherent errors are identified and factored into the algorithm that identifies free fall. The method provided herein allows for the 0 g offset to be monitored without having to reorient the device being tested, thus saving time and money.

Abstract: A latch apparatus is configured to latch an actuator arm assembly that can position a read/write head relative to a data storage disk in a disk drive. The latch apparatus includes a latch arm, a coil, a permanent magnet, and a latch control circuit. The latch arm is configured to be moved between a closed position that inhibits movement of the actuator arm assembly in a landing zone and an open position that does not inhibit movement of the actuator arm assembly in the landing zone. The coil is configured to generate an electromagnetic force on the latch arm responsive to a coil current. The permanent magnet is configured to generate a magnetic force on the latch arm that is substantially opposed to the electromagnetic force from the coil. The latch control circuit is configured to increase according to defined open current profiles over a defined opening time period the coil current to at least an upper defined level to cause the coil to move the latch arm from the closed position to the open position.

Abstract: A method and apparatus for providing a user selectable start-up current in a disk drive are provided. A user may select a relatively high start-up current to provide a relatively fast start-up time in a disk drive. Alternatively, the user may select a relatively low maximum current draw by the hard drive to enable a relatively low power, low cost power supply to be used in connection with the hard drive, for use with applications in which a relatively long start-up time is acceptable. In connection with applications in which a low cost power supply is to be used, the maximum current drawn by the disk drive may be limited to the amount of current required by the disk drive during seek operations.

Abstract: A reduction in computational load associated with correction of repeatable runout is provided. Rather than performing DFT for each analyzed frequency at each interrupt, at least some frequencies are not analyzed in the same interrupt period. DFTs for different frequencies may be staggered or interleaved. DFTs for different frequencies may be performed at different rates, preferably, using higher rates for higher frequencies.

Abstract: A PTP test subsystem of a magnetic disk drive identifies an undesired pole tip protrusion (PTP) condition, and takes steps to prevent problems associated with PTP. A PTP stressing mechanism stresses the disk drive during a PTP test mode to induce a PTP condition. A disk contact detection circuit detects when a head of the disk drive contacts the disk. A PTP write current determining circuit is also provided which comprises a write current level detector to ascertain a write current level at which the disk contact detection circuit detects when the head of the disk drive contacts the disk while the disk drive is stressed during the PTP test mode.

Abstract: A PTP test subsystem of a magnetic disk drive identifies an undesired pole tip protrusion (PTP) condition, and takes steps to prevent problems associated with PTP. A PTP stressing mechanism stresses the disk drive during a PTP test mode to induce a PTP condition. A disk contact detection circuit detects when a head of the disk drive contacts the disk. A PTP write current determining circuit is also provided which comprises a write current level detector to ascertain a write current level at which the disk contact detection circuit detects when the head of the disk drive contacts the disk while the disk drive is stressed during the PTP test mode.

Abstract: The invention is directed to a head positioning servo system for disk drives employing a dedicated servo surface. A plurality of servo cells are recorded on the servo surface each including a sync field for storing multiple magnetic flux transitions. Each sync field consists of multiple unit areas wherein each of said transitions is selectively stored in one or more of said unit areas. In the preferred embodiment, each sync field includes double frequency (2f) transitions which are stored in a single unit area and single frequency (1f) transitions which are stored in two adjacent unit areas. The two types of transitions are used to encode each sync field to define either a valid ("1") sync or a nonvalid ("0") sync. Valid syncs are detected to generate sync pulses for timing control to derive both rotational and radial position information from the servo surface.