A disk drive system is described which includes a disk having a magnetic surface
and a motor for rotating the disk, a magnetic head being movable relative to said
magnetic surface. The motor generates a back electromotive force voltage having
different phases and the system comprising a plurality of switches for switching
the back electromotive force voltage, a control circuit to control the plurality
of switches to supply the back electromotive force voltage to direct the head to
a parking position. The system also comprises a comparator adapted to compare a
single phase of the back electromotive force voltage with the sum of the other
phases of the back electromotive force voltage. The comparator generates an output
signal representative of the comparation and the system comprises a logic block
controlled by the output signal of the comparator. The logic block is adapted to
determine time periods and a control sequence of the switches which is associated
to the time periods. The control sequence is supplied to the control circuit so
that the last generates control signals to control the plurality of switches.
