Control circuit of switching regulator circuit and method for controlling switching regulator circuit

Abstract

A control circuit for a switching regulator circuit includes a reference signal generation circuit, an oscillator circuit, a feedback circuit, a coupling circuit, a comparator circuit, and a pulse width modulation (PWM) control circuit. The reference signal generation circuit generates an adjusted reference voltage based on a first reference voltage and a PWM signal. The oscillator circuit generates a sawtooth wave signal and a clock signal. The feedback circuit generates a feedback voltage based on the output voltage. The coupling circuit combines the adjusted reference voltage and the sawtooth wave signal to generate an adjusted sawtooth wave signal. The comparator circuit compares the input signal obtained from the feedback voltage and the adjusted sawtooth wave signal to output a comparison signal. The PWM control circuit generates a PWM signal based on the comparison signal and the clock signal.

Claims

1. A control circuit applied to a switching regulator circuit, comprising: a reference signal generation circuit for generating an adjusted reference voltage based on a first reference voltage and a pulse width modulation (PWM) signal; an oscillator circuit for generating a sawtooth wave signal and a clock signal; a feedback circuit for generating a feedback voltage based on an output voltage of the switching regulator circuit; a combining circuit for combining the adjusted reference voltage and the sawtooth wave signal to generate an adjusted sawtooth wave signal; a comparator circuit comprising a first input terminal, a second input terminal, and an output terminal, wherein the first input terminal is used to receive a first input signal obtained from the feedback voltage, the second input terminal is used to receive a second input signal obtained from the adjusted sawtooth wave signal, and the output terminal is used to output a comparison signal; and a PWM control circuit for generating the PWM signal based on the comparison signal and the clock signal.

2. The control circuit as claimed in claim 1, wherein the feedback circuit is used to feed back the output voltage of the switching regulator circuit as the feedback voltage.

3. The control circuit as claimed in claim 1, wherein the feedback circuit comprises: a voltage divider circuit for dividing the output voltage of the switching regulator circuit to generate a divided voltage as the feedback voltage.

4. The control circuit as claimed in claim 1, wherein the reference signal generating circuit comprises: an operational amplifier circuit including a non-inverting input, an inverting input, and an output, wherein the non-inverting input of the operational amplifier circuit is used to receive the first reference voltage, the output of the operational amplifier circuit is coupled to the inverting input of the operational amplifier circuit, and the adjusted reference voltage is generated at the output of the operational amplifier circuit; a compensation capacitor coupled between the output of the operational amplifier circuit and a reference; and a compensation branch circuit coupled between the output of the operational amplifier circuit and the reference, wherein the compensation branch circuit is used to control the adjusted reference voltage according to the pulse width modulation signal.

5. The control circuit as claimed in claim 4, wherein the compensation branch circuit includes an auxiliary switch and a current source, and the current source is connected in series with the auxiliary switch.

6. The control circuit as described in claim 5, wherein the auxiliary switch is controlled by the pulse width modulation signal.

7. The control circuit as described in claim 6, wherein the reference terminal is a ground terminal; and when the auxiliary switch is turned on by the pulse width modulation signal, the compensation capacitor is discharged by a current provided by the current source.

8. The control circuit as described in claim 5, wherein the current source of the compensation branch circuit is a constant current source.

9. The control circuit as claimed in claim 5, wherein the current source of the compensation branch circuit comprises: a controlled current source connected in series with the auxiliary switch; and a voltage-to-current control circuit for controlling the controlled current source to output a controlled current based on a control voltage.

10. The control circuit as described in claim 9, wherein the control voltage is an input voltage of the switching regulator circuit.

11. The control circuit as claimed in claim 5, wherein the current source of the compensation branch circuit comprises: a resistor connected in series with the auxiliary switch.

12. The control circuit as claimed in claim 5, wherein the current source of the compensation branch circuit comprises: a resistor connected in series with the auxiliary switch; a controlled current source connected in parallel with the resistor; and a voltage-to-current control circuit for controlling the controlled current source to output a controlled current based on a control voltage.

13. The control circuit as described in claim 12, wherein the control voltage is an input voltage of the switching regulator circuit.

14. The control circuit as claimed in claim 4, further comprising: an offset control circuit, comprising: an error amplifier for generating and outputting an error signal to an offset control terminal of the operational amplifier circuit based on the feedback voltage and the first reference voltage; wherein the operational amplifier circuit controls the adjusted reference voltage based on the first reference voltage and the error signal; the adjusted reference voltage is determined based on the first reference voltage and an offset voltage of the operational amplifier circuit; and the offset voltage is adjusted based on the error signal generated based on the feedback voltage and the first reference voltage.

15. The control circuit as claimed in claim 4, further comprising: an offset control circuit, comprising: an error amplifier for generating an error signal based on the feedback voltage and a second reference voltage; a voltage gain circuit for amplifying the error signal to generate an offset compensation signal; and a combination circuit for combining the offset compensation signal and the second reference voltage to generate and output the first reference voltage to the non-inverting input of the operational amplifier circuit.

16. The control circuit as claimed in claim 4, further comprising: an offset control circuit, comprising: an error amplifier for generating an error signal based on the feedback voltage and the first reference voltage; a voltage gain circuit for amplifying the error signal to generate an offset compensation signal; and a combination circuit coupled to the voltage gain circuit, the inverting input terminal of the operational amplifier circuit, and the output terminal of the operational amplifier circuit; wherein the operational amplifier circuit is used to generate the adjusted reference voltage based on the first reference voltage and the offset compensation signal.

17. The control circuit as claimed in claim 4, further comprising: an offset control circuit, comprising: an error amplifier for generating an error signal to an offset control terminal of the comparator circuit based on the feedback voltage and the first reference voltage; wherein the comparator circuit is configured to generate a comparison signal based on the error signal, the first input signal, and the second input signal; the comparison signal is determined based on the first input signal, the second input signal, and an offset voltage of the comparator circuit; and the offset voltage is adjusted based on the error signal generated based on the feedback voltage and the first reference voltage.

18. The control circuit as claimed in claim 4, further comprising: an offset control circuit, comprising: an error amplifier for generating an error signal based on the feedback voltage and the first reference voltage; and a voltage gain circuit for amplifying the error signal to generate an offset compensation signal; wherein the combining circuit combines the sawtooth wave signal, the offset compensation signal, and the adjusted reference voltage to generate the second input signal at the second input terminal of the comparator circuit.

19. The control circuit as claimed in claim 4, further comprising: an offset control circuit, comprising: an error amplifier for generating an error signal based on the feedback voltage and the first reference voltage; a voltage gain circuit for amplifying the error signal to generate an offset compensation signal; and a combination circuit for combining the offset compensation signal and the feedback voltage to generate the first input signal at the first input terminal of the comparator circuit.

20. A method for controlling a switching regulator circuit, comprising: generating an adjusted reference voltage based on a reference voltage and a pulse width modulation (PWM) signal; generating a sawtooth wave signal and a clock signal; generating a feedback voltage based on an output voltage of the switching regulator circuit; generating an adjusted sawtooth wave signal by combining the adjusted reference voltage and the sawtooth wave signal; comparing a first input signal obtained from the feedback voltage and a second input signal obtained from the adjusted sawtooth wave signal to generate and output a comparison signal; and generating the PWM signal based on the comparison signal and the clock signal.

Images