Abstract: A magnetic disk drive includes a switching regulator configured to generate an output voltage, and a magnetic disk control unit that receives the output voltage as a power supply and performs data write and read operations on a magnetic recording medium. The switching regulator includes a voltage conversion part configured to generate a second voltage by switching a first voltage, a smoothing part configured to smooth the second voltage to thus produce an output voltage, a control part configured to control the switching on the basis of a difference between the output voltage and a reference voltage to thus stabilize the output voltage, and a reference voltage changing part configured to change the reference voltage in accordance with an operation mode of the magnetic disk control unit.

Abstract: A magnetic disk drive for locking an actuator mounted with a magnetic head in a safety zone. The magnetic disk drive comprises a magnet, fixed yoke members and a stopper for setting a stop position of rotations of the rotary actuator in such a position that torque by the fixed yoke members and the magnet is maximized. The fixed yoke members form a magnetic circuit for the magnet in all or a part of a movable range of the rotary actuator. The fixed yoke members include a first area having a gap width uniformly reduced in a lock direction to retract the rotary actuator and a second area having a gap width smaller than a gap width of the first area. The fixed yoke members are mechanically separated from each other.