Switching regulator, motor drive device, magnetic disk storage device, and electronic apparatus

A motor drive device comprising:

• a spindle motor driver which drives a spindle motor;
• a voice coil motor driver which drives a voice coil motor;
• and
• a switching regulator, wherein
• the switching regulator comprises:
• an output stage which, with an output switch element, an inductor, a rectifying element, and a smoothing element, generates an output voltage from an input voltage;
• a divided voltage generator which generates a divided voltage from a switch voltage generated at one terminal of the rectifying element;
• a selector which outputs one of the divided voltage and a fixed voltage in accordance with a switching signal as a select voltage;
• a zero-cross comparator which monitors the select voltage to generate a zero-cross detection signal;
• and
• a controller which generates the switching signal in accordance with the necessity of monitoring the zero-cross of an inductor current and which performs on/off control of the output switch element reflecting the zero-cross detection signal.

A magnetic disk storage device comprising:

• a platter;
• a magnetic head which reads and writes data to and from the platter;
• a swing arm which holds the magnetic head at a tip end thereof;
• a spindle motor which rotates the platter;
• a voice coil motor which moves the swing arm in an arc;
• and
• a motor drive device which drives the spindle motor and the voice coil motor, and which provides the output voltage for relevant parts of the magnetic disk storage device, wherein
• the motor drive device comprises:
• a spindle motor driver which drives the spindle motor;
• a voice coil motor driver which drives the voice coil motor;
• and
• a switching regulator, wherein
• the switching regulator comprises:
• an output stage which, with an output switch element, an inductor, a rectifying element, and a smoothing element, generates an output voltage from an input voltage;
• a divided voltage generator which generates a divided voltage from a switch voltage generated at one terminal of the rectifying element;
• a selector which outputs one of the divided voltage and a fixed voltage in accordance with a switching signal as a select voltage;
• a zero-cross comparator which monitors the select voltage to generate a zero-cross detection signal;
• and
• a controller which generates the switching signal in accordance with the necessity of monitoring the zero-cross of an inductor current and which performs on/off control of the output switch element reflecting the zero-cross detection signal.

An electronic appliance comprising:

• a magnetic disk storage device, wherein
• the magnetic disk storage device comprises:
• a platter;
• a magnetic head which reads and writes data to and from the platter;
• a swing arm which holds the magnetic head at a tip end thereof;
• a spindle motor which rotates the platter;
• a voice coil motor which moves the swing arm in an arc;
• and
• a motor drive device which drives the spindle motor and the voice coil motor, and which provides the output voltage for relevant parts of the magnetic disk storage device, wherein
• the motor drive device comprises:
• a spindle motor driver which drives the spindle motor;
• a voice coil motor driver which drives the voice coil motor;
• and
• a switching regulator, wherein
• the switching regulator comprises:
• an output stage which, with an output switch element, an inductor, a rectifying element, and a smoothing element, generates an output voltage from an input voltage;
• a divided voltage generator which generates a divided voltage from a switch voltage generated at one terminal of the rectifying element;
• a selector which outputs one of the divided voltage and a fixed voltage in accordance with a switching signal as a select voltage;
• a zero-cross comparator which monitors the select voltage to generate a zero-cross detection signal;
• and
• a controller which generates the switching signal in accordance with the necessity of monitoring the zero-cross of an inductor current and which performs on/off control of the output switch element reflecting the zero-cross detection signal.