Power-supply device and hard disk drive using same

• US 20050127881A1
• Filed: 08/06/2004
• Published: 06/16/2005
• Est. Priority Date: 12/16/2003
• Status: Active Grant

• Current Assignee: Google LLC (Alphabet Inc.)
• Original Assignee: Hitachi, Ltd.
• Inventors: Kanouda, Akihiko, Sase, Takashi, Hayashi, Katsunori
• Granted Patent: US 7,170,273 B2
• Time in Patent Office: Days
• US Class Current: 323/225
• CPC Class Codes: H02M 1/0025 Arrangements for modifying reference values, feedback values or error values in the control loop of a converter
• CPC Class Codes: H02M 3/156 with automatic control of output voltage or current, e.g. switching regulators

Abstract

The object of the invention is to compensate an effect of a voltage drop emerging in output voltage by the equivalent series resistance of a power output filter in a power-supply device. To achieve the object, a power-supply device wherein the power output filter that passes output power and first and second filters provided separately from the power output filter are provided, the first filter provided separately and one input terminal of an error amplifier are connected, new reference voltage acquired by adding differential voltage between the output of the second filter provided separately and the output of the power output filter to reference voltage is input to the other input terminal of the error amplifier and an output signal is fed back to the error amplifier is provided. According to the power-supply device, a voltage drop by equivalent series resistance emerging the output voltage of the power-supply device can be compensated.

Claims

1. A power-supply device of a step-down type DC-DC converter provided with a power semiconductor switching device, driving means of the power semiconductor switching device, a pulse-width modulation oscillator that supplies a driving signal to the driving means and an error amplifier that supplies an error signal with reference voltage to the oscillator, comprising:

a power output filter that passes output power; and

first and second filters provided separately from the power output filter, wherein;

the first filter and one input terminal of the error amplifier are connected;

differential voltage between the output of the second filter and the output of the power output filter is added to the reference voltage; and

voltage acquired by the addition is input to the error amplifier.

2. The power-supply device according to claim 1, wherein:

the power output filter is an LC filter provided with an inductor and a capacitor;

the first and second filters are a CR filter provided with a capacitor and a resistor; and

the first and second filters are provided in parallel with the power output filter.

3. The power-supply device according to claim 1, wherein:

the power output filter is an LC filter provided with an inductor and a capacitor;

the first and second filters are a CR filter provided with a capacitor and a resistor;

the first and second filters are provided to both ends of the inductor of the power output filter and the first filter is connected to an input terminal of the error amplifier;

differential voltage between the second filter and the power output filter is added to the reference voltage; and

voltage acquired by the addition is input to the error amplifier.

4. The power-supply device according to claim 2, wherein:

differential voltage between the second filter and the power output filter is subtracted from the output voltage of the first filter and is input to the input terminal of the error amplifier; and

the reference voltage is input to the other input terminal of the error amplifier.

5. The power-supply device according to claim 2, wherein:

each frequency of the first and second filters is fCR, fCR2;

when a frequency of the power output filter is fLC, fLC<

fCR; and

relation that fCR2 is smaller than fCR by one digit or more is met.

6. The power-supply device according to claim 5, comprising:

a transient variation detecting circuit, wherein;

the transient variation detecting circuit detects output voltage from an output terminal of a CR circuit provided to both ends of the inductor of the power output filter;

in case the output voltage exceeds a predetermined upper limit value, a signal for setting the duty of the pulse-width modulation oscillator to 0% is output; and

in case the output voltage is equal to or smaller than a predetermined lower limit value, a signal for setting the duty of the pulse-width modulation oscillator to 100% is output.

7. The power-supply device according to claim 6, wherein:

a center of the predetermined upper and lower limit values of the transient variation detecting circuit is determined based upon voltage acquired by the addition.

8. The power-supply device according to claim 6, wherein:

width between the predetermined upper and lower limit values is set according to the ratio of the reference voltage before the addition or is set to fixed voltage.

9. The power-supply device according to claim 6, wherein:

the transient variation detecting circuit shares the CR circuit provided to both ends of the inductor of the power output filter with the second filter; and

the CR circuit functions as a second CR filter.

14. The power-supply device according to claim 1, wherein:

the power semiconductor switching device, the driving means of the power semiconductor switching device, the pulse-width modulation oscillator, the error amplifier and a transient variation detecting circuit that detects output voltage from an output terminal of the power output filter, outputs a signal for turning the duty of the pulse-width modulation oscillator to 0% in case the output voltage exceeds a predetermined upper limit value and outputs a signal for turning the duty of the pulse-width modulation oscillator to 100% in case the output voltage is a predetermined lower limit value or less are mounted on the same semiconductor substrate.

16. A power-supply device, wherein:

the power-supply device according to claim 5 is applied to an isolation type DC-DC converter.

17. An IC, wherein:

the power-supply device according to claim 1 is built in a semiconductor chip.

10. A power-supply device provided with plural power supply device units of a step-down type DC-DC converter provided with a power semiconductor switching device, driving means of the power semiconductor switching device, a pulse-width modulation oscillator that supplies a driving signal to the driving means and an error amplifier that supplies an error signal with reference voltage to the oscillator, wherein:

the plural power supply device units are respectively provided with a power output filter that passes output power and first and second filters provided separately from the power output filter;

the first filter and one input terminal of the error amplifier are connected;

differential voltage between the output of the second filter and the output of the power output filter is added to the reference voltage; and

voltage acquired by the addition is input to the error amplifier.

11. The power-supply device according to claim 10, wherein:

to operate the plural power supply device units in parallel, the pulse-width modulation oscillator is shared among the plural power supply device units;

the phase of the output of the pulse-width modulation oscillator shifts; and

a signal the phase of which shifts is supplied to the plural power supply device units.

12. The power-supply device according to claim 11, wherein:

the plural power supply device units are respectively provided with a transient variation detecting circuit;

the transient variation detecting circuit detects output voltage from the output terminal of the power output filter;

in case the output voltage exceeds a predetermined upper limit value, a signal for setting the duty of the pulse-width modulation oscillator to 0% is output; and

in case the output voltage is equal to or smaller than a predetermined lower limit value, a signal for setting the duty of the pulse-width modulation oscillator to 100% is output.

13. The power-supply device in multi-phase operation or in parallel operation according to claim 10, wherein:

to share current between/among plural power supply device units, a maximum value of differential voltage between the output of a second filter and the output of the power output filter in each power supply device unit is detected via a common bus; and

difference between the maximum value of the differential voltage and differential voltage in each power supply device unit between the output of the second filter and the output of the power output filter is added to voltage acquired by the addition.

15. A hard disk drive provided with a magnetic storage disk, a magnetic head, a magnetic-disk rotating device, a magnetic-head drive, a magnetic-head position controller, an input/output signal controller and a power-supply device that supplies power, wherein:

the power-supply device is a step-down type DC-DC converter power-supply device provided with a power semiconductor switching device, driving means of the power semiconductor switching device, a pulse-width modulation oscillator that supplies a driving signal to the driving means and an error amplifier that supplies an error signal with reference voltage to the oscillator; and

the power-supply device provided with a power output filter that passes output power and first and second filters provided separately from the power output filter wherein the first filter and one input terminal of the error amplifier are connected, differential voltage between the output of the second filter and the output of the power output filter is added to the reference voltage, voltage acquired by the addition is input to the error amplifier, the power output filter is an LC filter composed of an inductor and a capacitor, the first and second filters are a CR filter composed of a capacitor and a resistor, the first and second filters are provided in parallel with the power output filter, when frequencies of the first and second filters are fCR, fCR2 and a frequency of the power output filter is fLC, fLC<

fCR and relation that fCR2 is smaller than fCR by one digit or more is met and output is fed back to the error amplifier via the first and second filters is provided.