Method of operating hard disk drive, corresponding control circuit, hard disk drive and processing device

A control circuit comprising:

• retract logic circuitry configured to be coupled to a voice coil motor (VCM) in a hard disk drive, and configured to, during a retract phase:
• operate the VCM to retract read-and-write heads of the hard disk drive from a disk surface towards an end-of-travel parking condition with the heads climbing over a ramp starting from a ramp edge adjacent the disk surface;
• operate the VCM in a discontinuous mode comprising an alternation of on-times of a duration TON and off-times of a duration TOFF in which supply of a drive current to the VCM is facilitated and countered, respectively;
• and
• vary the duration TOFF of the off-times, with the duration TOFF of the off-times increasing from a first lower bound value at the ramp edge towards a first upper bound value as the heads climb over the ramp.

A hard disk drive, comprising:

• at least one voice coil motor (VCM);
• and
• a control circuit comprising retract logic circuitry coupled to the VCM and configured to, during a retract phase:
• operate the VCM to retract read-and-write heads of the hard disk drive from a disk surface towards an end-of-travel parking condition with the heads climbing over a ramp starting from a ramp edge adjacent the disk surface;
• operate the VCM in a discontinuous mode comprising an alternation of on-times of a duration TON and off-times of a duration TOFF in which supply of a drive current to the VCM is facilitated and countered, respectively;
• and
• vary the duration TOFF of the off-times, with the duration TOFF of the off-times increasing from a first lower bound value at the ramp edge towards a first upper bound value as the heads climb over the ramp.