A disk drive is connectable to a power supply having a fixed DC voltage.
The disk drive includes a voice coil motor (VCM) and a spindle motor
having a plurality of windings and a rotor rotatable at a variable
spin-rate. A spindle motor driver is coupled to the fixed DC voltage and
at least one of the windings for controlling the spin-rate of the rotor.
The rotor has permanent magnets that induce an AC voltage across the
windings while the rotor is rotating. A rectifier circuit rectifies the AC
voltage across at least one of the windings to produce a rectified DC
voltage. A first switch provides the rectified DC voltage to a first node.
A second switch provides the fixed DC voltage to the first node. The first
node has a first node DC voltage that is determined by the rectified DC
voltage provided by the first switch and the fixed DC voltage provided by
the second switch. The first node DC voltage is greater than the fixed DC
voltage during a track seeking operation in the disk drive. A VCM driver
includes switching elements that selectively provide the first node DC
voltage to the VCM. The increased VCM voltage allows faster access times
and more efficient VCM operation.