Abstract: A disk drive is disclosed comprising a disk, an actuator arm, a head connected to a distal end of the actuator arm, and a voice coil motor (VCM) for rotating the actuator arm about a pivot to actuate the head over the disk, wherein the VCM rotates the actuator arm into a latched positioned when the disk drive is idle. Disk drive control circuitry unlatches the actuator arm by applying a driving current to the VCM according to an open-loop current profile. The open-loop current profile comprises an acceleration pulse having an acceleration magnitude and an acceleration interval, and a deceleration pulse having a deceleration magnitude and a deceleration interval. The deceleration magnitude is substantially smaller than the acceleration magnitude, and the deceleration interval is substantially longer than the acceleration interval, to thereby attenuate acoustic noise when unlatching the actuator arm.

Abstract: A disk drive is disclosed comprising a disk, a head actuated radially over the disk, and a spindle motor for rotating the disk, the spindle motor comprising a plurality of windings and a rotor rotatable at a variable spin rate, wherein the rotor generates a back EMF (BEMF) voltage across the windings proportional to the spin rate of the rotor. A plurality of switching elements are coupled to the windings, and switch control logic generates switch control signals applied to the switching elements for commutating the spindle motor during normal operation and for generating an internal supply voltage from the BEMF during a spin down mode, the internal supply voltage for parking the head. A programmable signal generator generates a periodic signal, the periodic signal for periodically grounding the windings during the spin down mode in order to boost the internal supply voltage, wherein grounding the windings applies a braking torque to the spindle motor.