US 12,080,327 B2
Method of operating hard disk drives and corresponding control circuit
Ezio Galbiati, Agnadello (IT); Michele Boscolo Berto, Milan (IT); Giuseppe Maiocchi, Villa Guardia (IT); and Maurizio Ricci, Villa di Serio (IT)
Assigned to STMicroelectronics S.r.l., Agrate Brianza (IT)
Filed by STMicroelectronics S.r.l., Agrate Brianza (IT)
Filed on Jul. 19, 2023, as Appl. No. 18/354,797.
Claims priority of application No. 102022000016305 (IT), filed on Aug. 1, 2022.
Prior Publication US 2024/0038263 A1, Feb. 1, 2024
Int. Cl. G11B 5/54 (2006.01); H02P 7/025 (2016.01)
CPC G11B 5/54 (2013.01) [H02P 7/025 (2016.02)] 20 Claims
OG exemplary drawing
 
1. A method, comprising:
rectifying a back electromotive force of a spindle motor in a hard disk drive;
energizing a voice coil motor in the hard disk drive using the rectified back electromotive force of the spindle motor via a voice coil motor power stage to retract a head of the hard disk drive to a park position, wherein the head is retracted by moving the head towards the park position during a first retract phase, and retaining the head in the park position during a second retract phase by applying a bias voltage to the voice coil motor power stage during a bias interval of the second retract phase;
producing a saturation signal indicative of onset of saturation in the voice coil motor power stage; and
controlling the bias voltage during the second retract phase based on the saturation signal to counter saturation in the voice coil motor power stage.