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PWM control circuit for DC-DC converter

Imported: 23 Feb '17 | Published: 22 Oct '02

Yasushi Katayama

USPTO - Utility Patents

Abstract

An error amplification circuit is configured by cascading together an operational amplification circuit and a proportional integration control circuit, both having a fixed operation point (ground potential), so that even when the reference voltage is varied stepwise, the operation points of the circuits maintain as the ground potential. The DC—DC converter is prevented from generating excess output even when the reference voltage provided as the target value varies stepwise.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a circuit diagram showing a first embodiment of the present invention;

FIG. 2 is a circuit diagram showing a second embodiment of the present invention;

FIG. 3 is a circuit diagram showing a third embodiment of the present invention;

FIG. 4 is a circuit diagram showing a fourth embodiment of the present invention;

FIG. 5 is a circuit diagram showing a fifth embodiment of the present invention;

FIG. 6 is a circuit diagram showing a sixth embodiment of the present invention;

FIG. 7 is a block diagram showing a conventional example of a PWM control circuit for a DC—DC converter;

FIG. 8 is a circuit diagram showing a first specific example of the conventional DC—DC converter;

FIG. 9 is a circuit diagram showing a second specific example of the conventional DC—DC converter;

FIG. 10 is a circuit diagram showing a third specific example of the conventional DC—DC converter;

FIG. 11 is a conventional circuit diagram showing a specific example of a detection circuit and an error amplification circuit;

FIGS.

12(

a) and

12(

b) are explanatory graphs of the operation of the circuit shown in FIG. 11;

FIGS.

13(

a) and

13(

b) are explanatory graphs of the operation of the circuit shown in FIG. 1; and

FIG. 14 is an explanatory graph of the operation of the circuit shown in FIG.

5.

Claims

1. A PWM control circuit for a DC—DC converter, comprising:

2. A PWM control circuit for a DC—DC converter according to claim 1, wherein said second analog amplification circuit is a proportional integration control circuit.

3. A PWM control circuit for a DC—DC converter according to claim 1, further comprising a single positive power supply and a negative-side terminal connected to a ground potential, said comparison circuit or said DC—DC converter being configured so that an output voltage from the DC—DC converter is at its minimum when an output voltage from the error amplification circuit equals to an amplitude lower-limit potential of a carrier signal, and the error amplification circuit has an operation point set at a potential between the amplitude lower-limit potential of the carrier signal and the ground potential.

4. A PWM control circuit for a DC—DC converter according to claim 3, wherein said error amplification circuit includes at least one capacitor connected to a passive element for determining a gain of the error amplification circuit, and a switch connected parallel to the capacitor, said switch being turned on when said DC—DC converter and said PWM control circuit are stopped.

5. A PWM control circuit for a DC—DC converter, comprising:

6. A PWM control circuit for a DC—DC converter according to claim 5, further comprising a single positive power supply and a negative-side terminal connected to a ground potential, said comparison circuit or said DC—DC converter being configured so that an output voltage from the DC—DC converter is at its minimum when an output voltage from the error amplification circuit equals to an amplitude lower-limit potential of a carrier signal, and the error amplification circuit has an operation point set at a potential between the amplitude lower-limit potential of the carrier signal and the ground potential.

7. A PWM control circuit for a DC—DC converter according to claim 6, wherein said error amplification circuit includes at least one capacitor connected to a passive element for determining a gain of the error amplification circuit, and a switch connected parallel to the capacitor, said switch being turned on when said DC—DC converter and said PWM control circuit are stopped.

8. A PWM control circuit for a DC—DC converter according to claim 1, wherein said error amplification circuit is connected to the reference voltage so that when the reference voltage is changed to change the output voltage from the DC—DC converter, a transient response thereof is determined by a control gain of the error amplification circuit.

9. A PWM control circuit for a DC—DC converter according to claim 5, wherein said error amplification circuit is connected to a reference voltage so that when the reference voltage is changed to change the output voltage from the DC—DC converter, a transient response thereof is determined by a control gain of the error amplification circuit.