Patent ID: 7158332

Claim:
A magnetic disk storage system comprising: a first motor which rotates a magnetic disk; a first motor drive circuit which drives the first motor; a second motor which moves the magnetic head; a second motor drive circuit which drives the second motor, a boost circuit which boosts a voltage which is generated by rectifying a first back electromotive force of the first motor, so as to generate a first voltage when a first power supply to the magnetic disk storage system is interrupted; a magnetic head being adapted to make smaller a gap between the magnetic head and a surface of the magnetic disk as a rotational speed of the first motor increases; and a drive control circuit which controls the first motor drive circuit and the second motor drive circuit by using the first voltage, whereby performing a retract control which is such as shifting the magnetic head to a standby position when a first power supply to the system is interrupted, wherein when the first power supply to the magnetic disk storage system is interrupted, the drive control circuit causes the first motor drive circuit to perform a stepup converter operation by the drive control circuit supplying the first motor drive circuit with drive voltages having an amplitude value which is smaller than a value of the first back electromotive force of each of three phases of the first coil and is synchronized with the first back electromotive force of each of three phases of the first coil, so as to generate the voltage.