Switching regulator, motor drive device, magnetic disk storage device, and electronic apparatus
A switching regulator has 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.
1. A switching regulator comprising:
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.
2. The switching regulator according to claim 1 , wherein
the controller selects the divided voltage with the selector when a predetermined time passes after the output switch element is turned off, and after that, generates the switching signal so as to select the fixed voltage with the selector when the zero-cross detection signal becomes a logical level on the zero-cross detection.
3. The switching regulator according to claim 2 , wherein
the predetermined time is a minimum off-masking time for maintaining the output switch element in an off-state without depending on a feedback state of the output voltage after the output switch is turned off.
4. The switching regulator according to claim 1 , wherein
the controller turns on the output switch element after the zero-cross detection signal becomes the logical level on the zero-cross detection.
5. The switching regulator according to claim 1 ,
the divided voltage generator includes:
a resistance ladder which divides the switch voltage to generate the divided voltage; and
a speed-up capacitor which is connected to the resistance ladder in parallel.
6. The switching regulator according to claim 1 , further comprising:
a feedback voltage generator which generates a feedback voltage in accordance with the output voltage; and
a main comparator which compares the feedback voltage and a threshold voltage to generate an on-signal, wherein
the controller determine on-timing of the output switch element in accordance with both the on-signal and the zero-cross detection signal.
7. The switching regulator according to claim 1 ,
the output stage is a step-up type, a step-down type, or step-up/down type.
8. The switching regulator according to claim 1 ,
the output stage is a positive output type or a negative output type.
9. 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.
10. 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.
11. 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.