Abstract: A data storage device includes a disc, an actuator arm assembly, a servo clock, and a feedback and control system. The disc includes a top and bottom surfaces and a servo wedge. The servo wedge includes a top surface boundary and a bottom surface boundary. The actuator arm assembly supports a head pair configured for interaction with the top and bottom surfaces. The servo clock is configured to determine a top time at which the head pair encounters the top surface boundary and a bottom time at which the head pair encounters the bottom surface boundary during a disc read/write interaction. The feedback and control system is configured to determine an operation time difference; compare the operation time difference to a certification time difference correlating to a target vertical position of the actuator arm assembly relative to the disc; and move the actuator arm assembly to the target vertical position.

Abstract: A data storage device includes a disc, an actuator arm assembly, a servo clock, and a feedback and control system. The disc includes a top and bottom surfaces and a servo wedge. The servo wedge includes a top surface boundary and a bottom surface boundary. The actuator arm assembly supports a head pair configured for interaction with the top and bottom surfaces. The servo clock is configured to determine a top time at which the head pair encounters the top surface boundary and a bottom time at which the head pair encounters the bottom surface boundary during a disc read/write interaction. The feedback and control system is configured to determine an operation time difference; compare the operation time difference to a certification time difference correlating to a target vertical position of the actuator arm assembly relative to the disc; and move the actuator arm assembly to the target vertical position.

Abstract: In accordance with one embodiment of the described technology, a retract controller capacitor is charged using a back electromagnetic force voltage to produce a backup power source voltage, the retract controller capacitor is discharged to power a retract controller circuit, and an actuator arm of a storage drive is driven toward a desired location concurrently with the discharging operation.

Abstract: In accordance with one embodiment of the described technology, a retract controller capacitor is charged using a back electromagnetic force voltage to produce a backup power source voltage, the retract controller capacitor is discharged to power a retract controller circuit, and an actuator arm of a storage drive is driven toward a desired location concurrently with the discharging operation.

Abstract: An apparatus and associated methodology for retracting a first member in relation to a second member. The first member may be selectively moveable by a first motor and the second member may be selectively moveable by a second motor that operably generates a back electromagnetic force (BEMF) voltage VBEMF. In an embodiment a retract control circuit may control movement of the first member via the first motor in response to a loss of supply power to the second motor. An embodiment of the apparatus may include a backup power source storing a voltage VB after the loss of supply power. Another embodiment of the apparatus may include retract logic operative on the retract control circuit to divide the VB from the VBEMF to energize the first motor by the VBEMF and not the VB when the VB is greater than a predetermined threshold voltage and a loss of the supply power to the second motor is detected.

Abstract: An interface controller of a storage device configured to manage a write cache of the storage device responsive to changes in a voltage supply provided to the storage device. In one implementation, the interface controller reduces the size of the write cache responsive to the voltage supply dropping at or below a first threshold. The interface controller further disables write permissions to the write cache responsive the voltage supply dropping at or below a second threshold, wherein the second threshold is lower in magnitude that the first threshold. The interface controller periodically receives the voltage supply responsive to transmitting sequential requests to a servo firmware of the storage device.

Abstract: An interface controller of a storage device configured to manage a write cache of the storage device responsive to changes in a voltage supply provided to the storage device. In one implementation, the interface controller reduces the size of the write cache responsive to the voltage supply dropping at or below a first threshold. The interface controller further disables write permissions to the write cache responsive the voltage supply dropping at or below a second threshold, wherein the second threshold is lower in magnitude that the first threshold. The interface controller periodically receives the voltage supply responsive to transmitting sequential requests to a servo firmware of the storage device.

Abstract: Several readings of an actuator's location are taken with a given head while urging the actuator against a mechanical stop, which acts as a guide. These readings are useful, for example, for estimating certain offsets or for determining a nominal track range for a data surface.

Abstract: A method and apparatus for compensating for the asymmetrical phases of a spindle motor in a disc drive are provided. With the apparatus and method, compensation values are learned by sampling speed data during a period of operation of the disc drive where the speed is stable and only one control operation is performed per revolution of the disc. The sampled speed data is used to generate the compensation values for each of the phases of the spindle motor. The compensation values are stored in a compensation mechanism which is used by the spindle motor speed controller to provide compensation for the asymmetrical phases of the spindle motor. During Normal operation, the actual speed output of the spindle motor is measured and is subtracted from a reference speed to generate a difference speed value. Based on the corresponding electrical phase, the correct compensation value is fetched and is subtracted from the difference speed value to obtain a compensated difference speed value.

Abstract: A method and apparatus for compensating for the asymmetrical phases of a spindle motor in a disc drive are provided. With the apparatus and method, compensation values are learned by sampling speed data during a period of operation of the disc drive where the speed is stable and only one control operation is performed per revolution of the disc. The sampled speed data is used to generate the compensation values for each of the phases of the spindle motor. The compensation values are stored in a compensation mechanism which is used by the spindle motor speed controller to provide compensation for the asymmetrical phases of the spindle motor. During Normal operation, the actual speed output of the spindle motor is measured and is subtracted from a reference speed to generate a difference speed value. Based on the corresponding electrical phase, the correct compensation value is fetched and is subtracted from the difference speed value to obtain a compensated difference speed value.